KR100891008B1 - Lighting apparatus of flat panel type - Google Patents

Abstract

Disclosed is a flat lighting device. A flat lighting device including a main light source for emitting blue light, a light excitation sheet positioned in an emission path of blue light to convert the blue light into white light, and an auxiliary light source that emits light so as to be mixed with the white light and whose luminance is adjustable. Since the auxiliary light source is mixed with the white light converted from the main light source, light having excellent color rendering properties can be realized.

Main light source, light guide plate, optical excitation sheet, reflective sheet, protective film

Description

Lighting apparatus of flat panel type

1 is a perspective view of a flat panel lighting apparatus according to a first preferred embodiment of the present invention.

2 is a cross-sectional view of a flat panel lighting apparatus excluding a frame according to a first preferred embodiment of the present invention.

3 is a color coordinate of a flat panel lighting apparatus using a red LED as an auxiliary light source as a first preferred embodiment of the present invention.

4 is a light spectrum graph of a flat panel lighting apparatus according to a first preferred embodiment of the present invention.

5 is a color coordinate using an orange LED as an auxiliary light source as a second preferred embodiment of the present invention.

6 is a cross-sectional view of a light excitation sheet according to a third preferred embodiment of the present invention.

Fig. 7 is a sectional view of a light excitation sheet according to a fourth preferred embodiment of the present invention.

8 is a photograph of an optical excitation sheet with a small ball according to a fourth preferred embodiment of the present invention.

9 is a cross-sectional view of a light excitation sheet according to a fifth preferred embodiment of the present invention.

10 is a cross-sectional view of a flat panel lighting apparatus excluding a frame according to a sixth exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

21: Light guide plate 22: light excitation sheet

23: reflective sheet 24: main light source

25: auxiliary light source 26: diffuser plate

27: frame

Various types of lamps are used to provide light or to illuminate an object at night or indoors. Such a lamp is to supply power or irradiate an object by converting electrical energy into light energy by receiving power, and generally use an incandescent lamp or a fluorescent lamp. However, incandescent lamps and fluorescent lamps have high power consumption and heat generation characteristics, and have a short life of about 6 months, and thus have to be frequently replaced. In addition, fluorescent lamps use mercury, which is a carcinogen, and are subject to regulation, and the direct light causes flickering of the light source, which acts as a cause of decreased vision, and requires a large installation space.

On the other hand, a variety of color temperature should be implemented with a single light source for the interior of the room for the purpose. Lighting sources using the same discharge principle as conventional fluorescent lamps are difficult to continuously control the color temperature. On the other hand, light sources using the blackbody radiation principle by heating filaments such as incandescent lamps and halogens have excellent color rendering properties, but do not implement color temperature of more than 3,500K.

The present invention is to provide a flat type lighting device that can be implemented by white light using the main light source, and additionally coupled to the auxiliary light source, the color temperature can be adjusted.

According to an aspect of the invention, the main light source for emitting blue light, a light excitation sheet which is located in the emission path of the blue light to convert the blue light to white light, and the light emitted to be mixed with the white light, the auxiliary brightness is adjustable Provided is a flat lighting device comprising a light source. By mixing the auxiliary light source with the white light converted from the main light source, light having excellent color rendering properties can be realized.

The main light source can adjust the brightness, and it is preferable to use a blue LED. Preferably, the auxiliary light source uses a red LED.

The photoexcited sheet preferably includes a matrix resin layer, a phosphor contained in the matrix resin layer, and a protective film laminated on the upper and lower surfaces of the matrix resin layer. The light excitation sheet converts the main light source into white light.

Roughness is formed on the protective film, or a small ball for preventing stains is preferably attached.

Hereinafter, a preferred embodiment of a flat panel lighting apparatus according to the present invention will be described in detail with reference to the accompanying drawings. In the description with reference to the accompanying drawings, the same components will be denoted by the same reference numerals regardless of the reference numerals and redundant description thereof will be omitted.

1 is a perspective view of a flat panel lighting apparatus according to a first preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view of a flat panel lighting apparatus excluding a frame according to a first exemplary embodiment of the present invention. 1 and 2, the flat lighting device 20, the light guide plate 21, the light excitation sheet 22, the reflective sheet 23, the main light source 24, the auxiliary light source 25, and the diffusion plate ( 26, a frame 27 is shown.

The light guide plate 21 is a flat transparent layer having a constant thickness and functions to convert light of the main light source 24, which is a point light source, into a surface light source. The light guide plate 21 may be manufactured in accordance with the width of the flat lighting device 20 to be set.

The main light source 24 is positioned at the side of the light guide plate 21. The main light source 24 is preferably in contact with the side of the light guide plate 21 so that light can be emitted into the light guide plate 21. It is preferable that such a main light source 24 uses a blue LED. This is because the emitted wavelength can be converted into a long wavelength after passing various phosphors in a short wavelength, and is inexpensive in terms of price. Thus, different types of LEDs can be used for the same purpose. On the other hand, the main light source 24 is attached to the printed circuit board to receive power from an external power source, the brightness can be adjusted by controlling the current.

In order to increase the brightness of the lighting device, the number of main light sources 24 may be increased. In addition, the main light source 24 may be attached to one side of the light guide plate 21 as well as to the other side thereof. This makes it possible to implement a high brightness lighting device.

The reflective sheet 23 is positioned on the lower surface of the light guide plate 21. The reflective sheet 23 is preferably attached to the light guide plate 21. The reflective sheet 23 is attached to the light guide plate 21 to act as a kind of mirror. The reflective sheet 23 may use a material made of silver in order to increase reflection efficiency. On the other hand, since the reflective sheet 23 is attached to the light guide plate 21, blue light of the main light source 24 emitted from the side surface is converted into white light through the light excitation sheet 22, and is emitted to the front of the light guide plate 21. A pattern for improving the reflection efficiency may be formed on the reflective sheet 23, and the light guide plate 21 may be inclined at regular intervals and the reflective sheet 23 may be attached to the surface thereof. In this case, the white light converted by the main light source 24 is emitted to the front of the light guide plate 21 along the inclined surface.

The light excitation sheet 22 positioned between the light guide plate 21 and the main light source 24 serves to convert blue light into white light. In addition, the main light source is converted into white light of various color temperatures. The structure of the optical excitation sheet 22 will be described later in detail. On the other hand, white light can be used for the main light source 24 without using blue light. In this case, the optical excitation sheet 22 of FIG. 2 is not necessary. At this time, a white LED can be used as the white light source, and the color temperature is preferably 5,000K or more.

On the other hand, the auxiliary light source 25 is coupled adjacent to the main light source 24. The auxiliary light source 25 preferably uses a red LED. The auxiliary light source 25 can adjust the brightness by controlling the current. Therefore, the white light converted from the main light source 24 and the light emitted by the auxiliary light source 25 are mixed to become mixed light having high color rendering properties. In the present embodiment, a red LED was used as the auxiliary light source. However, blue light emitted by a blue LED (not shown) may be converted into red light using a light excitation sheet (not shown) using a red phosphor, and white light emitted from a white LED (not shown) may be converted into red light. An excitation sheet (not shown) may be used to convert the light into red light.

3 is a color coordinate of the flat lighting device according to the first preferred embodiment of the present invention, wherein the white light converted from the dark-colored LED 24 is located at A2, and the light emitted from the red LED is located at B. FIG. These mixed lights are changed to C1, C2, and C3. When the luminance of the red LED, which is the auxiliary light source 25, is increased, the mixed light is moved in the color coordinates from C1 to C3, and the color temperature is gradually decreased at 6700K (A2). Since the color temperature of sunlight is about 5000K, only the auxiliary light source 25 may be controlled to move the color coordinates of the mixed light to be closer to the color temperature of the sunlight. On the other hand, when the color coordinates of the white light converted by the main light source 24 is 5000K (A3), when mixed with the light of the auxiliary light source 25 it can implement another mixed light.

In a method similar to the above embodiment, all of the blue LED, the red LED, and the green LED are used, and the current supplied thereto is controlled to implement white light or mixed light corresponding to a desired color coordinate. The use of a large number of LEDs is not preferable in terms of manufacturing cost, and since the LEDs have a narrow spectrum, the primary colors of blue, red, and green are excessively emphasized when lighting is applied, and thus, comfortable lighting cannot be realized. It is also difficult to control each of them. Furthermore, there is a problem in that the color coordinates move because the lifetime of each LED is different as time passes. Therefore, as shown in the present embodiment, it is significant to implement mixed light having various color coordinates using only the main light source 24 and the auxiliary light source 25.

On the other hand, using such an auxiliary light source 25 has a significant meaning in terms of color rendering. 4 is a light spectrum graph of a flat panel lighting apparatus according to a first preferred embodiment of the present invention. The G1 graph shown in the graph of FIG. 4 is a spectrum of white light in which light emitted from the main light source 24 is converted via the light excitation sheet 22, and the G2 graph is obtained from a red LED which is an auxiliary light source 25 in the G1 graph. The emitted light is combined light implemented. As shown in the graph, G2 has an even distribution of wavelengths throughout the visible region. Thus, the color rendering is close to sunlight.

In the first embodiment, the auxiliary light source 25 and the main light source 24 are coupled to the light guide plate side, but this is only one embodiment and the structure thereof may be changed in various ways. The main light source 24 may be positioned on the lower surface of the light excitation sheet 22 so as to be emitted directly to the light excitation sheet 22 without using the light guide plate, and the auxiliary light source 25 may be positioned at a position spaced apart from the main light source 24. You can also combine.

On the other hand, the auxiliary light source 24 may use an orange LED. 5 is a color coordinate when using an orange LED as a second preferred embodiment of the present invention. 5D is a color coordinate of light emitted from the orange LED, and mixed light C1, C2, and C3 exist on a straight line connecting the coordinates A2 of the white light converted from the blue LED.

The optical excitation sheet serves to convert blue light emitted from the blue LED into white light, and plays an important role in the present invention. The structure will be described in detail below.

6 is a cross-sectional view of a light excitation sheet according to a third preferred embodiment of the present invention. Referring to Fig. 6, yellow phosphor 41a, red phosphor 41b, green phosphor 41c, phosphor 41, matrix resin layer 42, diffuser 43, protective film 44, photoexcitation Sheet 40 is shown.

The light excitation sheet 40 shown in FIG. 6 has a function of converting light of a main light source having a wavelength of 400 nm to 500 nm into white light. Basically, the phosphor 41 is evenly distributed in the matrix resin layer 42 of the thin film.

Although not shown in FIG. 6, a curing agent and an additive may be included in the matrix resin layer 42. The curing agent is used to cure the liquid thermosetting resin, and the additive is used to evenly disperse the phosphor 41 in the liquid thermosetting resin. The diffusing agent 43 promotes the refraction of the light source to increase the excitation rate of the phosphor 41 and serves to homogenize.

The protective film 44 serves to protect the matrix resin layer 42. In general, the lifetime of the main light source is tens of thousands of hours with blue LEDs. In order to ensure the heat resistance and moisture resistance of the light excitation sheet 40 to correspond to the lifespan of the main light source for a long time, a protective film 44 that protects the phosphor 41 is essential.

As the resin usable as the protective film 44 of the present invention, a colorless transparent synthetic resin is used, which is excellent in light transmittance, but is not particularly limited. For example, polyethylene terephthalate (PET), polyethylene naphthalate ( Polyethylene naphthalate, acrylic resin, polycarbonate, polystyrene, and the like. Among them, polyethylene terephthalate (PET) film is excellent in transparency, and excellent in strength and warpage. In addition, when heat resistance and chemical resistance are needed, it is preferable to make the protective film 44 polycarbonate. As for the thickness of the protective film 44, it is preferable to use the film within 5-50 micrometers. This is because a film of 10 μm or less is difficult to handle, and a film of 50 μm or more is inferior in light transmittance.

The phosphor 41 uses an inorganic phosphor. Typical photo-excited inorganic phosphors are composed of phosphors doped with cerium in Y3Al5O12 (YAG), a garnet-based (Gd) material. For example, the photoexcited inorganic phosphor is (Y1-x-yGdxCey) 3Al ₅ O ₁₂ (YAG: Gd, Ce), (Y1-xCex) ₃ Al ₅ O ₁₂ (YAG: Ce), (Y1-xCex) ₃ (Al1-yGay) ₅ O ₁₂ (YAG: Ga, Ce), (Y1-x-yGdxCey) ₃ (Al5-zGaz) ₅ O ₁₂ (YAG: Gd, Ga, Ce), (Gd1-xCex) SC ₂ Al ₃ O ₁₂ (GSAG).

In general, YAG-based phosphors are represented by (Y1-x-yGdxCey) ₃ (Al1-zGaz) O ₁₂ (where x + y ≦ 1; 0 ≦ x ≦ 1; 0 ≦ y ≦ 1; 0 ≦ z ≦ 1). do. The main wavelength emitted by the phosphor 41 depends on the materials described above. Ce3 + emission depending on the garnet composition can emit light from green (~ 540 nm; YAG: Ga, Ce) to red (~ 600 nm; YAG: Gd, Ce) without decreasing the light efficiency. In the example of the present invention, (Y, Gd, Ce) ₃ (Al, Ga) ₅ O ₁₂ of the main kettle and Y ₃ Al ₅ O _12: Ce of Phosphor Technology Inc. were used. In addition, a representative inorganic phosphor for emitting deep reds is SrB 4 O 7: Sm ²⁺ . SM ²⁺ mainly contributes to the red wavelength. In particular, the deep red inorganic phosphor absorbs the entire visible light region of 600 nm or less and emits light having a deep red color, that is, a wavelength of 650 nm or more. Phosphor Technology's SrS: Eu-based 620nm wavelength phosphor is used to improve brightness. In addition, a representative inorganic phosphor for emitting green light is SrGa ₂ S ₄ : Eu ²⁺ . Such a green inorganic phosphor absorbs light of 500 nm or less and emits a main wavelength of 535 nm. In addition, a representative inorganic phosphor for emitting blue light is BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ . Such a blue inorganic phosphor absorbs light of 430 nm or less and emits a main wavelength of 450 nm.

The yellow phosphor may use not only the YAG series but also one of TAG (Tb3Al5O12) and Silicate (Sr2SiO4: Eu). In addition, the red phosphor may use one of CaS: Eu, SrS: Eu, and SrB4O7: Sm, and a green phosphor may be used as SrGa2S4: Eu.

7 is a cross-sectional view of an optical excitation sheet according to a fourth preferred embodiment of the present invention, and FIG. 8 is a photograph of an optical excitation sheet with a small ball according to a fourth preferred embodiment of the present invention. Referring to FIG. 7, a phosphor 51, a matrix resin layer 52, a diffusing agent 53, a protective film 54, a small ball 55, an adhesive layer 56, and an optical excitation sheet 50 are shown. have.

The fourth embodiment of the present invention is characterized in that the small balls 55 are attached to the surface of the optical excitation sheet 10. When the small balls 55 are evenly distributed and adhered to the surface of the optical excitation sheet 10, staining due to the adhesion of the surfaces does not occur even if other kinds of sheets are located on the upper and lower surfaces.

It is preferable that such a small ball 55 also be made of resin, and it is preferable to use a transparent material so as not to degrade the brightness. The small ball 55 may be directly attached to the surface of the optical excitation sheet 50, but the application of the adhesive layer 56 to the upper surface allows the small ball 55 to be stably attached without being separated.

9 is a cross-sectional view of a light excitation sheet according to a fifth preferred embodiment of the present invention.

Referring to FIG. 9, a phosphor 71, a matrix resin layer 72, a diffusing agent 73, a protective film 74, an adhesive layer 76, and a photoexcitation sheet 70 are illustrated.

In the case of the fifth embodiment, roughness was formed in the protective film 74. This is for effectively dispersing the light. That is, the light incident on the matrix resin layer 72 passes through the protective film 74 twice, and the path of the light is dispersed in various ways by the illuminance of the protective film 74. Therefore, the dispersion material 73 may not be used for such an optical excitation sheet 70. In addition, the rough surface of the protective film 74 also has a function of preventing the stain phenomenon due to the adhesion of the surface when the other type of sheet is located on the upper surface.

10 is a cross-sectional view of a flat panel lighting apparatus excluding a frame according to a sixth exemplary embodiment of the present invention. Referring to FIG. 10, the flat lighting device 90, the light guide plate 91, the light excitation sheet 92, the reflective sheet 93, the main light source 94, the auxiliary light source 95, and the diffusion plate 96 are Is shown.

This embodiment is generally the same as the first embodiment of FIG. To explain the difference, the light excitation sheet 92 is interposed between the main light source 94 and the light guide plate 91. The optical excitation sheet 92 includes a phosphor capable of converting wavelengths. Therefore, the wavelength of the blue LED which is the main light source 94 is converted into white. It is a red LED which emits the red light of the auxiliary light source 95 adjacent to the main light source 94.

The remaining configuration of this embodiment is in accordance with the first embodiment of FIG. In addition, the optical excitation sheet 92 may be applied to the embodiments of FIGS. 6, 7, 8, and 9.

Although the technical spirit of the present invention has been described in detail according to the above-described embodiments, the above-described embodiments are for the purpose of description and not of limitation, and a person of ordinary skill in the art will appreciate It will be understood that various embodiments are possible within the scope.

According to the embodiment having the above configuration, not only can realize white light as one main light source, but also can realize a mixed light having excellent color rendering properties by using an auxiliary light source, thereby providing a flat lighting device suitable for a purpose. have.

Claims (8)

A main light source capable of controlling luminance and emitting blue light; An optical excitation sheet positioned in the emission path of the blue light and converting the blue light into white light having a plurality of color temperatures; And an auxiliary light source that emits mixed light with the white light to emit mixed light having improved color rendering property. The method of claim 1, The main light source is a flat lighting device, characterized in that the brightness can be adjusted. The method of claim 1, And said main light source is a blue LED. The method of claim 1, And the auxiliary light source is a red LED. The method of claim 1, The auxiliary light source is a flat lighting device, characterized in that the green LED. The method of claim 1, The photoexcitation sheet is a matrix resin layer; A phosphor contained in the matrix resin layer; And a protective film laminated on upper and lower surfaces of the matrix resin layer. delete The method of claim 6, Light excitation sheet, characterized in that the small ball for preventing stains is attached to the surface of the protective film.

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