KR101414643B1 - lighting apparatus and method for controlling the same - Google Patents

Abstract

The present invention relates to an LED lighting device capable of controlling light characteristics such as color temperature and a control method thereof. The present invention provides an LED lighting device including an LED light source and a variable color filter operated by an electrowetting principle in order to selectively transmit or block light of a specific wavelength band from light emitted from the LED light source.

Description

[0001] The present invention relates to a lighting apparatus and method for controlling the same,

The present invention relates to an LED illumination device and a control method thereof, and more particularly, to an LED illumination device and a control method thereof capable of actively controlling the characteristics of light emitted from an LED.

An LED (light emitting diode) is a semiconductor device that emits light when a forward voltage is applied due to an electroluminescence effect. LED has high efficiency and longer life than fluorescent or incandescent bulbs, and has recently become a spotlight as a lighting device. The emission color emitted from the LED differs depending on the material used for fabricating the LED, and it is possible to manufacture light from the ultraviolet region to the visible region and the infrared region.

It is preferable that a white LED is used to use the LED for illumination. However, due to manufacturing problems, white LEDs are difficult to mass produce illumination devices having the same color coordinates, and it is very difficult to control the color temperature and the color rendering index (CRI), which are important performance indicators. However, recently, it has been known that the color temperature of illumination affects user's concentration and mental fatigue, and it is time to consider the role of so-called 'emotional illumination'. Therefore, in recent years, technologies capable of controlling the color temperature of the LED illumination have been proposed.

There are two methods of adjusting the color temperature in the conventional LED illumination device. In the first method, a phosphor is disposed around the light emitting element, and the principle that the color temperature changes while light emitted from the light emitting element passes through the light emitting element is applied. In the second method, a plurality of light emitting devices having different color temperatures are disposed in one package, and the color temperature is adjusted by adjusting the number of light emitting devices to be lit or turned on.

However, in the case of the first method, the color temperature can not be actively controlled, and a complicated manufacturing process and management are required to manufacture a light emitting device having various color temperatures. In the case of the second method, the color temperature can be actively controlled, but a plurality of LED elements must be used and a complicated control system for controlling the color temperature is required.

Currently, the technology used for adjusting the color temperature in an LED illumination device is two light emitting devices having different color temperatures. That is, it is possible to control the color temperature by using an LED package showing a warm white color temperature characteristic and an LED package having a cool white color temperature characteristic or by using a cool white LED and a red LED Adjust the color temperature. However, since all of these methods require additional LEDs, they are not popularized due to price problems. Accordingly, it is required to develop an LED lighting device which can actively control the characteristics of illumination light such as color tone and color temperature, and which is simple in control and manufacture, without using a large number of light emitting elements.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an LED lighting device and a control method thereof that can more effectively control the characteristics of illumination light such as a color tone and a color temperature.

It is still another object of the present invention to provide an LED lighting device and a control method thereof that are easy to manufacture.

In order to solve the above-described problems, the present invention provides a light source device comprising: an LED light source; And a variable color filter operated by electrowetting principle for selectively transmitting or blocking light of a specific wavelength band from light emitted from the LED light source.

The variable color filter includes: a hydrophobic dielectric portion; A polar liquid provided in the hydrophobic dielectric portion; And a driver for selectively applying a voltage to the hydrophobic dielectric portion. Preferably, the hydrophobic dielectric portion further comprises a non-polar liquid having a transmission spectral characteristic different from the transmission spectral characteristic of the polar liquid. At this time, it is preferable that the non-polar liquid is a colored liquid having a predetermined color tone and color rendering property. It is preferable that the non-polar liquid is an oily liquid. Further, it is preferable that the polar liquid is a transparent liquid, and the polar liquid is more preferably an aqueous liquid.

The driving unit may include: a first electrode unit disposed on one side of the hydrophobic dielectric; And a second electrode portion located on the other side of the hydrophobic dielectric. The driving unit preferably applies a voltage to a part of the hydrophobic dielectric part. It is further preferable that a first transparent portion is provided under the first electrode portion and a second transparent portion is provided at an upper portion of the second electrode portion.

The variable color filter is preferably composed of a plurality of cells. And, it is desirable that the cells have at least one of a shape and an arrangement randomly or pseudo-randomly. In addition, the cells are preferably a set of a plurality of cells having different transmission spectrum 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 provides a method of manufacturing a semiconductor device, comprising: placing a polar liquid on a hydrophobic dielectric; Selectively applying a voltage to the hydrophobic dielectric to selectively move the polar liquid so as to selectively transmit or block light of a specific wavelength band from the light emitted from the LED light source, .

Preferably, the hydrophobic dielectric further comprises a non-polar liquid, and the non-polar liquid coalesces or spreads as the polar liquid is selectively moved. It is further preferable that a voltage is selectively applied to a part of the hydrophobic dielectric. Preferably, the polar liquid is a transparent aqueous liquid, and the nonpolar liquid is a colored oily liquid.

Effects of the LED illumination device and the control method according to the present invention will be described as follows.

First, in the LED lighting apparatus and the control method thereof according to the present invention, it is possible to adjust the color temperature and the like in a more easy way by using the principle of electrowetting, and to actively control various color temperatures according to the user's preference There is an advantage to doing.

Secondly, in the LED lighting apparatus and the control method thereof according to the present invention, the LED element or the LED package used as the light source can be realized by only one type or one type having a predetermined color temperature characteristic. Therefore, There is an advantage that it is cheaper than the conventional technology using a plurality of LEDs.

Thirdly, in the LED lighting apparatus and the control method thereof according to the present invention, the color temperature of the LED element can be finely adjusted, and the uniformity of the characteristics between the elements can be secured.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing the principle of electrowetting used in the present invention
2 is a sectional view showing a preferred embodiment of the LED illumination device according to the present invention
Fig. 3 is a cross-sectional view showing a unit variable color filter of the LED illumination device of Fig. 2
4 is a graph showing the ratio of the voltage to the transparent region in the unit variable color filter of the LED illumination device of Fig. 2
5 is a plan view showing another embodiment of the LED illumination device according to the present invention.
6 is a schematic cross-sectional view showing another embodiment of the LED illumination device 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 illumination device 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 by using an adjustable color filter that passes only a specific wavelength region of light emitted from a light emitting element, that is, an LED, and serves as an optical shutter, and the variable color filter is electrowetting ) Principle. Electric wetting phenomena were discovered by physicist G. Lippmann in the early 1900s and are based on the phenomenon that the wetting properties of hydrophobic surfaces are changed by an applied electric field.

First, with reference to Fig. 1, the electric wetting principle will be described.

On the hydrophobic dielectric material layer 120, water or an aqueous solution droplet has a property to keep the surface area as small as possible by the action of the surface tension of the liquid itself. Thus, in the normal state, the liquid exists in the form 100 having a large contact angle? 1 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 unit 130 and the second electrode unit 140, electrostatic energy accumulates between the liquid and the hydrophobic dielectric layer 120. Then, the liquid droplet spreads over a large area because the contact angle [theta] 2 with the surface of the hydrophobic dielectric layer 120 becomes small in order to balance the energy between the interfaces by the added electrostatic energy. Therefore, it is present in the spread form 101. In the LED illumination device 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 FIG. 2, a preferred embodiment of the LED illumination device according to the present invention will now be described. First, the overall configuration of the LED illumination device according to the present embodiment will be described.

 A variable color filter 320 is provided above the LED light source 310, that is, in the light irradiation direction. The LED light source 310 may include an LED element, a package including an LED element, and a phosphor for implementing a predetermined color spectrum. Further, the variable color filter 320 is preferably composed of a plurality of unit variable color filters serving as microscopic optical shutters. 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 the color temperature or 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 is a diagram showing a state in which an external electric field is not applied to the variable color filter 320, and FIG. 3B is a diagram showing a state in which an external electric field is applied to the variable color filter 320. FIG.

Each of the unit cells 322 is provided with a unit variable color filter 321. Preferably, the plurality of cells 322 are partitioned by barrier ribs 230, and the cells 322 are arranged in a pixel shape. 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 from light emitted from an LED light source (not shown). For this purpose, the unit variable color filter 321 basically includes a hydrophobic dielectric portion 240, a polar liquid 260 and a non-polar liquid 270 provided on the hydrophobic dielectric portion 240, 240 for selectively applying a voltage to the electrodes 220, 250, and 280, respectively.

That is, when a voltage is applied to the hydrophobic dielectric portion 240 by the driving portions 220, 250 and 280, the polar liquid 260 moves and the non-polar fluid 270 coalesces with the movement of the polar liquid 260, Thereby selectively transmitting or blocking light in the wavelength region. For example, when the nonpolar fluid 270 is in a coherent state, light from the LED light source passes through the polar liquid 260 and exits to the outside. When the nonpolar fluid 270 is in a spread state, the light emitted from the LED light source passes through the nonpolar liquid 270 and the polar liquid 260 and exits to the outside, so that the color temperature and the like can be adjusted. .)

On the other hand, it is preferable that the polar liquid 260 and the nonpolar liquid 270 have different transmission spectral characteristics. For example, the non-polar liquid 270 can be a colored liquid having a predetermined color tone and color rendering property, and the colored liquid can be configured in a form of dispersing one or a plurality of dyes. The polar liquid 260 may be a colorless transparent liquid containing an aqueous solution, a polar liquid having a predetermined transmission spectrum, or a polar liquid prepared by dispersing and dissolving the pigment to have a predetermined transmission spectral characteristic different from that of the nonpolar liquid Lt; / RTI > It is also preferred that the polar liquid 260 is an aqueous liquid and the nonpolar liquid 270 is an oily liquid so that the polar liquid 260 and the nonpolar liquid 270 do not mix with each other.

As described above, the polar liquid 260 and the nonpolar liquid 270 may be used in various ways. However, in the following explanation, the polar liquid 260 is a transparent aqueous liquid and the nonpolar liquid 270 is a colored liquid The non-polar liquid 270 is used to adjust the color temperature and the like. Figure 3 shows this example.

Hereinafter, a driving unit for selectively applying a voltage to the hydrophobic dielectric member 240 will be described. The driving unit includes a first electrode unit 250 positioned below the hydrophobic dielectric unit 240 and a second electrode unit 220 spaced apart from the hydrophobic dielectric unit 240, And a control power supply 280 for connecting the first electrode unit 250 and the second electrode unit 220 to each other. It is preferable that the first electrode unit 250 is provided on a portion of the hydrophobic dielectric 240 except for a part of the hydrophobic dielectric 240. That is, it is preferable that a non-electrode area 251 is provided in a part of the hydrophobic dielectric part 240, and that the non-electrode area 251 is optically opaque. That is, when a voltage is applied to the unit variable color filter 321, it is preferable that the non-polar liquid 270 is aggregated in the non-electrode area 251. The first electrode unit 250 and the second electrode unit 220 are preferably transparent and transmit light as they are. A first transparent part 290 is provided under the first electrode part 250 and a second transparent part 210 is provided on the second electrode part 220. The unit transparent color filter 321 As shown in Fig.

3A and 3B, the operation of the LED illumination device according to the present embodiment will be described as follows. 3A is a diagram showing a state in which no external electric field is applied to the variable color filter, and FIG. 3B is a diagram showing a state in which an external electric field is applied to the variable color filter.

The polar liquid 260 such as water or an aqueous solution (hereinafter referred to as a transparent polar liquid) and the non-polar colored oily liquid 270 (hereinafter, (Hereinafter referred to as "liquid"). Particularly, the movement at the interface between the transparent polar liquid 260 and the colored nonpolar liquid 270 will be mainly described.

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

The unit equilibrium variable that is not applied to the external electric field in the color filter 321, _{state, [γ o, w + γ} o, i <γ w, i] (γ: surface tension, o: oily liquid (oil), w: Naturally the colored nonpolar liquid 270 is positioned between the transparent polar liquid 260 and the hydrophobic dielectric portion 240 due to the relationship between the interfacial tension represented by water or an aqueous solution or water or saline, 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 the light of the spectrum distribution transmitted by the colored nonpolar liquid 270. Since cell 322 is a very small size, preferably less than 2 mm, it is desirable that the surface tension, which is the force acting between the interfaces, is much greater than gravity. In this way, the film of colored nonpolar liquid 270 remains stable and continuous in all directions in the 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 balanced system. Therefore, the state in which the colored nonpolar liquid 270 and the transparent polar liquid 260 are laminated (the state shown in FIG. 3A) is no longer maintained. The transparent polar liquid 260 moves in contact with the surface of the hydrophobic dielectric 240 to move in a direction that lowers the overall energy of the system. Thus, the colored nonpolar liquid 270 is pushed from the surface of the hydrophobic dielectric portion 240, but is agglomerated in the non-electrode 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 aggregated, and this region becomes transparent. Accordingly, the cell 322 transmits light emitted from an LED light source (not shown) provided under the cell 322 without color transition.

That is, as described above, according to the LED illumination device according to this embodiment, it is possible to adjust the color temperature or the like emitted from the LED light source by selectively flocculating or spreading the colored nonpolar liquid 270. Also, by controlling the voltages applied to the first electrode unit 250 and the second electrode unit 220, the light emitted from the LED light source can be controlled more finely.

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

4 is a graph showing the ratio of the area occupied by the transparent region to the area of the unit cell according to the voltage applied to the electrode. When the voltage is between (0 - _Vth ), the colored nonpolar liquid 270 hardly agglomerates. Therefore, since the colored nonpolar liquid 270 is spread over the whole of the cell 322, the area ratio of 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, and thereby the color developed by the colored nonpolar liquid 270 becomes. That is, as shown in FIG. 4 (a), the entire area of the cell 322 is colored with a predetermined color. As shown in FIG. 4 (b), as the voltage increases, the colored nonpolar liquid 270 becomes flocculated, and accordingly, only the region where the colored nonpolar liquid 270 is present, that is, The area also increases. In this case, the color of the LED light source is mixed with the transmission color of the predetermined colored nonpolar liquid 270. As shown in (c) of FIG. 4, when the voltage further increases and the voltage reaches the predetermined value V _full or more, the transparent region becomes 80% or more. In this case, the light emitted from the LED light source is transmitted through almost no color mixture. Therefore, as described above, it is possible to finely control the color density or the like of the unit variable color filter by controlling the voltage in the unit variable color filter to adjust the transparent area.

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

The present embodiment is also the same as the above-described embodiment in basic principle. However, this embodiment differs from the above-described embodiment in the shape of the cell 322 or the unit variable color filter 321. In the above-described embodiment (see Fig. 3), cells 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 form of the variable color filter and the LED light source, the spacing distance, the size of the LED light source, and the like. For example, if unit cells are arranged with a predetermined period, diffraction interference due to periodic slit arrangement through which light is transmitted may appear.

Therefore, in the present embodiment, 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 in order to suppress such a phenomenon do. For example, the shape of the cell 322 may be a random or pseudo-random shape. Alternatively, the arrangement of cells 322 may be in a random or pseudo-random fashion with no spatial periodicity or suppression. Or cells of various sizes may be arranged in a spatially random or pseudo-random fashion. Of course, it is also possible to use these methods in combination.

5 (a) is a view showing a color developed state in which light transmitted through a colored non-polar liquid spreading on the surface of a cell 322 is filtered with a predetermined hue, FIG. 5 (b) And the outgoing light of the LED light source is transmitted through a transparent portion other than the cohesion region without color transition.

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

The present embodiment is also the same as the above-described embodiments in basic principle. However, in this embodiment, a unit cell or a unit variable filter is configured for each wavelength band or color. With this structure, arbitrary color adjustment in the visible light region is possible. The details will be described below.

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 the light transmission characteristic that allows the consumer or the user to obtain a desired color tone and color rendering property . The color density can be arbitrarily controlled by electrically controlling the area in which a single colored non-polar liquid contacts the cell. In this embodiment, since each of the cells is divided into respective wavelength bands or colors, arbitrary color adjustment in the visible light region is possible.

For example, as shown in FIG. 6, a plurality of cells 321a, 321b, and 321c having different characteristics according to respective wavelength bands or colors may be formed as a single layer on the same plane. Alternatively, as shown 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, the cells 321a, 321b, and 321c or the filters for the respective wavelength bands are shown schematically for convenience. However, the unit variable color filters shown in FIG. 3 are installed in each of the cells 321a, 321b, and 321c.

In the present embodiment, each of the cells 321a, 321b, and 321c is independently applied with a voltage, so that the contact area of the colored nonpolar liquid spread on the surfaces of the cells 321a, 321b, and 321c is independently Can be adjusted. As a result, it is possible to control the characteristics of light emitted from the LED light source 310, for example, various fine colors, color density, and color temperature by a variable color filter.

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

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

Claims (19)

An LED light source;
And a variable color filter operated by an electrowetting principle for selectively transmitting or blocking light of a specific wavelength band from light emitted from the LED light source,
Wherein the variable color filter comprises a non-polar liquid having a hydrophobic dielectric portion, a polar liquid having a transmission spectral characteristic different from that of the polar liquid, and a driving portion for applying a voltage selectively to the hydrophobic dielectric portion Including,
The nonpolar liquid is a colored liquid having a predetermined color tone and color rendering property,
The color temperature of the light emitted from the LED light source is adjusted so that the light emitted from the LED light source has a warm white color temperature characteristic or a warm white color temperature characteristic as a voltage is selectively applied to the hydrophobic dielectric portion,
Wherein the driving unit includes a first electrode unit disposed on one side of the hydrophobic dielectric unit and a second electrode unit disposed on the other side of the hydrophobic dielectric unit,
The driving unit applies a voltage to a part of the hydrophobic dielectric part,
Wherein the first electrode part is provided on a portion of the hydrophobic dielectric part except for a part of the hydrophobic dielectric part so as to have an electrode-
Wherein when the voltage is applied to the variable color filter, the non-polar liquid coheres in the non-electrode area. delete delete delete The method of claim 1, wherein the nonpolar liquid is an oily liquid,
Wherein the polar liquid is a transparent liquid and is an aqueous liquid. delete delete delete delete delete 2. The LED illumination device according to claim 1, wherein the variable color filter comprises a plurality of cells. delete 12. The LED illumination device according to claim 11, wherein the cells are a set of a plurality of cells having different transmission spectrum characteristics. 14. The LED illumination device according to claim 13, wherein the plurality of cells are arranged on the same plane. 14. The LED illumination device according to claim 13, wherein the plurality of cells are stacked in multiple layers. delete delete delete delete

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