KR20120080340A - Lighting apparatus and method for controlling the same - Google Patents

Abstract

PURPOSE: An LED lighting device and a control method thereof are provided to obtain uniformity of property of LED devices by minutely adjusting color temperature of the LED devices according to user's preference. CONSTITUTION: A plurality of unit cells(322) respectively comprises a unit variable color filter(321). The plurality of unit cells is divided by a partition wall. The unit variable color filter selectively transmits or blocks light of a specific wavelength band. The unit variable color filter comprises a hydrophobic dielectric part(240), a polar liquid(260), a non-polar liquid(270), and driving parts(220, 250, 280). The polar liquid and the non-polar liquid have different transmission spectra property. The driving parts selectively apply a voltage to the hydrophobic dielectric part.

Description

LED lighting apparatus and method for controlling the same

The present invention relates to an LED lighting apparatus and a control method thereof, and more particularly, to an LED lighting apparatus and a control method thereof that can actively adjust the characteristics of the light emitted from the LED.

An LED (light emitting diode) is a semiconductor device that emits light when a forward voltage is applied by an electroluminescent effect. LED has high efficiency and long lifespan compared to fluorescent lamps and incandescent bulbs. The color of light emitted from the LED depends on the material used to make the LED, and it is possible to manufacture light emitting from the ultraviolet region to the visible light and the infrared region.

In order to use an LED for lighting, it is preferable that a white LED is used. However, due to manufacturing problems, white LEDs are difficult to produce lighting devices having the same color coordinates, and it is very difficult to control color temperature and color rendering index (CRI), which are important performance indicators. However, recently, it is known that the color temperature of lighting affects the user's concentration, mental fatigue, and the like, and it is time to consider the role as so-called 'emotional lighting'. Therefore, recently, techniques for controlling the color temperature of LED lighting have been proposed.

In the conventional LED lighting apparatus, there are two methods of adjusting color temperature. The first method is to apply the principle that the color temperature is changed while the phosphor is disposed around the light emitting device so that the light from the light emitting device passes through the light emitting body. The second method is a method of controlling the color temperature by controlling the brightness or the number of the light emitting device is turned on by placing two or more light emitting devices having different color temperatures in one package.

However, in the case of the first method, the color temperature cannot be actively controlled, and complicated manufacturing processes and management are required to manufacture light emitting devices having various color temperatures. In case of the second method, the color temperature can be actively controlled, but the disadvantage is that a plurality of LED elements must be used and a separate complicated control system for adjusting the color temperature is required.

Currently, a technique generally used for color temperature control in LED lighting apparatuses is to use two light emitting devices having different color temperatures. That is, the color temperature is controlled by using an LED package having a warm white color temperature characteristic and an LED package having a cool white color temperature characteristic, or by using a cool white characteristic LED and a red LED. Adjust the color temperature. However, all of these methods are not popularized due to price issues because additional LEDs are required. Accordingly, there is a demand for development of an LED lighting device that can actively adjust characteristics of illumination light such as color tone and color temperature without using a plurality of light emitting elements, and is simple to control and manufacture.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an LED lighting apparatus and a control method thereof, which can more effectively adjust the characteristics of illumination light, such as color tone, color temperature and the like.

Still another object of the present invention is to provide an LED lighting device and a method of controlling the same, which are easy to manufacture.

In order to solve the above problems, the present invention includes an LED light source; In order to selectively transmit or block light having a specific wavelength band among the light emitted from the LED light source, an LED lighting apparatus including a variable color filter operated by an electrowetting principle is provided.

The variable color filter includes a hydrophobic dielectric portion; A polar liquid provided on the hydrophobic dielectric portion; It is preferable to include a driving unit for selectively applying a voltage to the hydrophobic dielectric portion. The hydrophobic dielectric portion is further preferably provided with a nonpolar liquid having a transmission spectrum characteristic different from that of the polar liquid. At this time, the nonpolar liquid is preferably a colored liquid having a predetermined color tone and color rendering property. In addition, the nonpolar liquid is preferably an oil liquid. The polar liquid is preferably a transparent liquid, and more preferably the polar liquid is an aqueous liquid.

On the other hand, the driving unit, the first electrode portion located on one side of the hydrophobic dielectric; It is preferable to include a second electrode portion located on the other side of the hydrophobic dielectric. The driving unit preferably applies a voltage to a portion of the hydrophobic dielectric unit. In addition, it is more preferable that a first transparent part is provided below the first electrode part, and a second transparent part is provided above the second electrode part.

On the other hand, the variable color filter is preferably composed of a plurality of cells. The cells are preferably at least one of a shape and an arrangement are random or pseudo-random. In addition, the cells are preferably a collection of a plurality of cells having different transmission spectral characteristics. The plurality of cells may be arranged on the same plane, and the plurality of cells may be stacked in multiple layers.

According to another embodiment of the present invention, the present invention comprises the steps of disposing a polar liquid over a hydrophobic dielectric; It provides a control method of the LED lighting device comprising selectively applying a voltage to the hydrophobic dielectric to selectively move the polar liquid to selectively transmit or block light of a specific wavelength band from the light emitted from the LED light source. .

The hydrophobic dielectric further includes a nonpolar liquid, and it is preferable that the nonpolar liquid aggregates or spreads as the polar liquid is selectively moved. It is further desirable to selectively apply a voltage to a portion of the hydrophobic dielectric. Preferably, the polar liquid is a transparent aqueous liquid, and the nonpolar liquid is a colored oily liquid.

The effects of the LED lighting apparatus and the control method according to the present invention described above are as follows.

First, in the LED lighting apparatus and the control method according to the present invention, it is possible to adjust the color temperature, etc. in an easier way by using the principle of electric wetting, and also to actively adjust the various color temperature according to the user's preference There is an advantage.

Secondly, in the LED lighting apparatus and the control method thereof according to the present invention, since the LED element or the LED package used as the light source can be implemented by one or only one having a predetermined color temperature characteristic, two or more having different color temperature characteristics There is an advantage that it is cheaper than the prior art using a plurality of LEDs.

Third, in the LED lighting apparatus and the control method according to the present invention, it is possible to finely adjust the color temperature of the LED element, there is an advantage that can ensure the uniformity of the characteristics between the elements.

1 is a view showing the principle of electrowetting used in the present invention
2 is a cross-sectional view showing a preferred embodiment of the LED lighting apparatus according to the present invention
3 is a cross-sectional view showing a unit variable color filter of the LED lighting apparatus of FIG.
4 is a graph illustrating a ratio of a voltage and a transparent region in a unit variable color filter of the LED lighting apparatus of FIG.
5 is a plan view showing another embodiment of the LED lighting apparatus according to the present invention
Figure 6 is a schematic cross-sectional view showing yet another embodiment of the LED lighting apparatus according to the present invention
7 is a schematic cross-sectional view showing another embodiment of the LED illumination device according to the present invention

Hereinafter, an LED lighting apparatus and a control method thereof according to the present invention will be described with reference to the accompanying drawings.

In the present invention, the color temperature is adjusted using an adjustable color filter that acts as an optical shutter by passing only a specific wavelength region of light emitted from the light emitting device, that is, the LED, and the variable color filter is electrowetting. ) Is implemented using the principle. The electrowetting phenomenon was discovered by physicist G. Lippmann et al in the early 1900s and is based on the change in the wetting properties of hydrophobic surfaces by an applied electric field.

First, referring to FIG. 1, the electrowetting principle will be described.

Drops of water or aqueous solution on the hydrophobic dielectric material layer 120 have the property of maintaining the surface area as small as possible by the surface tension of the liquid itself. Thus, in the normal state, the liquid is present in the form 100 with a large contact angle θ1 with the surface of the hydrophobic dielectric layer 120. However, when a voltage is applied to the liquid and the conductive plate 110 through the first electrode 130 and the second electrode 140, the electrostatic energy is accumulated between the liquid and the hydrophobic dielectric layer 120. The liquid droplet then spreads over a large area by reducing the contact angle θ2 with the surface of the hydrophobic dielectric layer 120 to achieve energy balance between the interfaces by the added electrostatic energy. Thus, it is present in the spread form 101. In the LED lighting apparatus according to the present invention, a variable color filter for adjusting the color temperature and the like is implemented using this electrowetting principle.

Referring to Figure 2, it will be described a preferred embodiment of the LED lighting apparatus according to the present invention. First, the overall configuration of the LED lighting apparatus according to the present embodiment will be described.

 The variable color filter 320 is provided above the LED light source 310, that is, the light irradiation direction. The LED light source 310 may include an LED element, a package including the LED element, a phosphor for implementing a predetermined color spectrum, and the like. In addition, the variable color filter 320 may include a plurality of unit variable color filters serving as a fine optical shutter. For example, it is preferable that the variable color filter 320 is divided into a plurality of cells, and a unit variable color filter 321 is provided in each cell so that color temperature and the like can be adjusted in each cell.

Referring to FIG. 3, the unit variable color filter 321 will be described in detail as follows. 3A illustrates a state in which no external electric field is applied to the variable color filter 320, and FIG. 3B illustrates a state in which an external electric field is applied to the variable color filter 320.

Each of the unit cells 322 is provided with a unit variable color filter 321. The plurality of cells 322 are preferably partitioned by the partition wall 230, and the cells 322 are preferably arranged in a pixel form. The unit variable color filter 321 or the variable color filter 320 will be described in detail as follows.

The unit variable color filter 321 selectively transmits or blocks light of a specific wavelength band among lights emitted from an LED light source (not shown). To this end, the unit variable color filter 321 basically includes a hydrophobic dielectric part 240, a polar liquid 260 and a nonpolar liquid 270 provided on the hydrophobic dielectric part 240, and the hydrophobic dielectric part ( It is configured to include a driver 220, 250, 280 to selectively apply a voltage to 240.

That is, when a voltage is applied to the hydrophobic dielectric part 240 by the driving units 220, 250, and 280, the polar liquid 260 moves, and the nonpolar fluid 270 aggregates as the polar liquid 260 moves. It selectively transmits or blocks light in the wavelength range. For example, when the nonpolar fluid 270 is agglomerated, light emitted from the LED light source passes through the polar liquid 260 to the outside. When the non-polar fluid 270 is spread, the light emitted from the LED light source passes through the non-polar liquid 270 and the polar liquid 260 to the outside, thereby controlling color temperature and the like. .)

Meanwhile, the polar liquid 260 and the nonpolar liquid 270 preferably have different transmission spectral characteristics. For example, the nonpolar liquid 270 may be a colored liquid having a predetermined color tone and color rendering, and the colored liquid may be configured in a form in which one or a plurality of dyes are dispersed. The polar liquid 260 may be a colorless transparent polar liquid containing an aqueous solution, a polar liquid having a predetermined transmission spectrum, or a polar liquid prepared so that pigments are dispersed and dissolved to have predetermined transmission spectrum characteristics different from that of the nonpolar liquid. Can be done. In addition, since the polar liquid 260 is an aqueous liquid and the nonpolar liquid 270 is an oil liquid, it is preferable that the polar liquid 260 and the nonpolar liquid 270 are not mixed with each other.

As described above, the polar liquid 260 and the nonpolar liquid 270 may be used in various ways, but for convenience of explanation in the following description, the polar liquid 260 is a transparent aqueous liquid and the nonpolar liquid 270 is colored. Since it is an oil liquid, it adjusts color temperature etc. by the nonpolar liquid 270 as an example. 3 illustrates this example.

Meanwhile, the driving unit for selectively applying a voltage to the hydrophobic dielectric part 240 will be described. The driving unit may include a first electrode part 250 positioned below the hydrophobic dielectric part 240, a second electrode part 220 positioned above and spaced apart from the hydrophobic dielectric part 240, and the first electrode. It is preferably configured to include a control power supply 280 connecting the unit 250 and the second electrode 220. In addition, the first electrode part 250 is preferably provided at a portion except for a part of the hydrophobic dielectric part 240. That is, it is preferable that the electrodeless region 251 is provided in a portion of the hydrophobic dielectric portion 240, and the electrodeless region 251 is processed to be optically opaque. That is, when a voltage is applied to the unit variable color filter 321, it is preferable to cause the nonpolar liquid 270 to aggregate in the electrodeless region 251. In addition, the first electrode part 250 and the second electrode part 220 may be transparent to transmit light as it is. In addition, a first transparent part 290 is provided below the first electrode part 250, and a second transparent part 210 is provided above the second electrode part 220 to provide a unit variable color filter 321. It is preferable to serve as a housing of).

Referring to Figures 3a and 3b, the operation of the LED lighting apparatus according to the present embodiment will be described. 3A is a diagram illustrating a state in which no external electric field is applied to the variable color filter, and FIG. 3B is a diagram illustrating a state in which an external electric field is applied to the variable color filter.

In the present embodiment, the unit cell 322 has a polar liquid 260 such as water or an aqueous solution (hereinafter referred to as 'transparent polar liquid' for convenience of explanation) and a non-polar colored oily liquid 270 (hereinafter referred to as 'colorless non-polar'). Liquid), and particularly, the movement of the transparent polar liquid 260 and the colored nonpolar liquid 270 at the interface.

Referring to FIG. 3A, a state in which no external electric field is applied to the unit variable color filter 321 will be described first.

In an equilibrium state where no external electric field is applied to the unit variable color filter 321, [γ _{o, w} + γ _{o, i} <γ _{w, i} ] (γ: interface tension, o: oily liquid, w: By the relationship between the interfacial tension expressed in water or saline (i: insulator), the naturally colored nonpolar liquid 270 is positioned between the transparent polar liquid 260 and the hydrophobic dielectric portion 240. do. That is, the colored nonpolar liquid 270 is spread over the entire surface of the unit cell 322, and the cell 322 transmits only light having a spectral distribution transmitted by the colored nonpolar liquid 270. Since the cell 322 is of a very small size, preferably less than 2 mm, it is desirable that the surface tension, the force acting between the interfaces, be much greater than gravity. In this way, the film of colored nonpolar liquid 270 remains stable and continuous in all directions in cell 322.

Next, a state in which an external electric field is applied to the unit variable color filter 321 will be described with reference to FIG. 3B.

When a voltage is applied between the transparent polar liquid 260 and the first electrode unit 250 through the second electrode unit 220, electrostatic energy is added to the energy balance system. Therefore, the state in which the colored nonpolar liquid 270 and the transparent polar liquid 260 are stacked (the state shown in FIG. 3A) can no longer be maintained. That is, the transparent polar liquid 260 moves in contact with the surface of the hydrophobic dielectric portion 240 to move in the direction of lowering the overall energy of the system. Thus, the colored nonpolar liquid 270 is pushed out of the surface of the hydrophobic dielectric portion 240 and aggregates in the electrodeless region 251 of the cell 322. That is, the transparent polar liquid 260 is located in a region other than the region where the colored nonpolar liquid 270 is agglomerated, and this region is in a transparent state. Therefore, the cell 322 transmits the light emitted from the LED light source (not shown) provided below the cell 322 without any color transition.

That is, as described above, according to the LED lighting apparatus according to the present embodiment, by selectively agglomerated or spreading the colored nonpolar liquid 270, it is possible to adjust the color temperature and the like emitted from the LED light source. In addition, by controlling the voltages applied to the first electrode unit 250 and the second electrode unit 220, it is possible to more finely control the light emitted from the LED light source.

Referring to FIG. 4, a method of finely controlling the light emitted from the LED light source by controlling voltages applied to the first electrode part 250 and the second electrode part 220 will be described.

4 is a graph showing the ratio of the area occupied by the transparent area to the area of the unit cell according to the voltage applied to the electrode. When the voltage is between (0-V _th ), the colored nonpolar liquid 270 hardly aggregates. Therefore, since the colored nonpolar liquid 270 is spread throughout the cell 322, the area ratio occupied by the transparent region in the cell 322 is close to zero. Accordingly, the light emitted from the LED light source passes through the colored nonpolar liquid 270, thereby becoming a colored state of the colored nonpolar liquid 270. That is, as shown in FIG. 4A, the entire area of the cell 322 is colored in a predetermined color. As shown in FIG. 4B, as the voltage increases, the colored nonpolar liquid 270 aggregates, and thus, the transparent non-polar liquid 270 does not exist, that is, the transparent polar liquid 260 is present. The area will also increase. In this case, the color of the LED light source and the transmission color by the predetermined color nonpolar liquid 270 are mixed. As shown in Fig. 4C, when the voltage is further increased and the voltage is greater than or equal to the predetermined value V _full , the transparent region becomes 80% or more. In this case, the light emitted from the LED light source is transmitted with almost no color mixing. Therefore, as described above, by controlling the voltage in the unit variable color filter to adjust the transparent area, it is possible to finely adjust the color density and the like of the unit variable color filter.

Referring to Figure 5, another embodiment of a variable color filter according to the present invention will be described.

This embodiment also has the same basic principle as the above-described embodiment. However, in the present embodiment, the shape of the cell 322 or the unit variable color filter 321 is different from that of the above-described embodiment. In the above-described embodiment (see Fig. 3), cell or unit variable color filters are arranged with a predetermined period. However, the spatial distribution of the light intensity emitted by the diffraction phenomenon may be uneven depending on the arrangement of the variable color filter and the LED light source, the separation distance, the size of the LED light source, and the like. For example, when unit cells are arranged with a predetermined period, diffraction interference due to a periodic slit arrangement through which light is transmitted may appear.

Therefore, in this embodiment, in order to suppress this phenomenon, the shape and arrangement of the cells 322 or the unit variable color filters 322 constituting the variable color filter are configured in a random or pseudo-random manner. do. For example, the shape of cell 322 may be a random or pseudo-random shape. Alternatively, the arrangement of the cells 322 can be in a random or pseudo-random manner with no spatial periodicity or suppressed. Alternatively, cells having various sizes may be arranged in a spatially random or pseudo-random manner. Of course, it is also possible to use a combination of these methods.

FIG. 5 (a) is a view illustrating a color development state in which light transmitted through a colored nonpolar liquid spreading on the surface of the cell 322 is filtered to a predetermined color. FIG. It is a figure which shows the state which the light emitted by the LED light source transmits to the transparent parts other than the aggregation area | region without color transition.

6 and 7, another embodiment of the variable color filter according to the present invention will be described.

This embodiment also has the same basic principle as the above-described embodiments. However, in the present embodiment, a unit cell or a unit variable filter is configured for each wavelength band or color. This configuration allows arbitrary color adjustment within the visible light region. It will be described in detail as follows.

In the above-described embodiment (see FIG. 3), a single colored nonpolar liquid is used for all the cells, and the single colored nonpolar liquid is selected to have a light transmitting property to obtain a color tone and color rendering property preferred by the consumer or the user. . And the color density can be arbitrarily adjusted by electrically controlling the area where a single colored nonpolar liquid contacts the cell. However, in the present embodiment, since each cell is configured by dividing each wavelength band or color, arbitrary color adjustment is possible in the visible light region.

For example, as illustrated in FIG. 6, a plurality of cells 321a, 321b, and 321c having different characteristics for each wavelength band or color may be configured in a single layer on the same layer. Alternatively, as illustrated in FIG. 7, a plurality of cells 321a, 321b, and 321c may be stacked in multiple layers for each wavelength band or color. In FIG. 7, cells 321a, 321b, and 321c of each wavelength band or filters are schematically illustrated for convenience, but each of the cells 321a, 321b, and 321c is provided with a unit variable color filter illustrated and described with reference to FIG. 3.

On the other hand, in the present embodiment, each of the cells 321a, 321b, and 321c is independently supplied with a voltage, so that the contact area of the colored nonpolar liquid spreading on the surface of each of the cells 321a, 321b, and 321c is independently. I can regulate it. As a result, it is possible to adjust the characteristics of the light emitted from the LED light source 310, for example, various fine colors, color density and color temperature by using a variable color filter.

The present invention is not limited to the above-described embodiment, and various modifications are possible using the basic principles of the present invention. For example, in the above-described embodiment, the use of a colored nonpolar liquid and a transparent polar liquid together is illustrated and described, but it is also possible to use one liquid, for example, a colored polar liquid. In addition, although the above-described embodiment described the LED light source as the light source, the present invention is not limited thereto.

310: LED light source 320: variable color filter
321 cell 240 hydrophobic dielectric material
260: transparent polar liquid 270: colored nonpolar liquid
250, 220: first electrode portion, second electrode portion 290, 210: first transparent portion, second transparent portion

Claims (19)

LED light source;
LED lighting device including a variable color filter operated by the electro-wetting principle to selectively transmit or block light of a specific wavelength band among the light emitted from the LED light source. 2. The variable color filter of claim 1, further comprising: a hydrophobic dielectric portion; A polar liquid provided on the hydrophobic dielectric portion; And a driving unit for selectively applying a voltage to the hydrophobic dielectric part. The LED illuminating device according to claim 2, wherein the hydrophobic dielectric part is further provided with a nonpolar liquid having a transmission spectrum characteristic different from that of the polar liquid. 4. The LED lighting apparatus according to claim 3, wherein the nonpolar liquid is a colored liquid having a predetermined color tone and color rendering property. The LED lighting device of claim 4, wherein the nonpolar liquid is an oil liquid. The LED lighting apparatus of claim 4, wherein the polar liquid is a transparent liquid. The LED lighting device of claim 6, wherein the polar liquid is an aqueous liquid. The apparatus of claim 2, wherein the driving part comprises: a first electrode part positioned at one side of the hydrophobic dielectric material; LED lighting device, characterized in that it comprises a second electrode portion located on the other side of the hydrophobic dielectric. The LED lighting apparatus of claim 8, wherein the driving unit applies a voltage to a portion of the hydrophobic dielectric part. The LED lighting apparatus of claim 9, wherein a first transparent part is provided below the first electrode part, and a second transparent part is provided above the second electrode part. 4. The LED lighting apparatus according to claim 2 or 3, wherein the variable color filter is composed of a plurality of cells. 12. The LED lighting device of claim 11, wherein said cells are at least one of a shape and an arrangement being random or pseudo-random. 12. The LED lighting apparatus of claim 11, wherein the cells are a collection of a plurality of cells having different transmission spectral characteristics. The LED lighting apparatus of claim 13, wherein the plurality of cells are arranged on the same plane. The LED lighting apparatus of claim 13, wherein the plurality of cells are stacked in a multilayer. Disposing a polar liquid over the hydrophobic dielectric;
Selectively applying a voltage to the hydrophobic dielectric to selectively move the polar liquid to selectively transmit or block light of a specific wavelength band from the light emitted from the LED light source. 17. The method of claim 16, wherein the hydrophobic dielectric further includes a nonpolar liquid, and the nonpolar liquid aggregates or spreads as the polar liquid is selectively moved. 18. The method of claim 17, wherein a voltage is selectively applied to a portion of the hydrophobic dielectric material. 19. The control method according to claim 18, wherein the polar liquid is a transparent aqueous liquid, and the nonpolar liquid is a colored oily liquid.

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