KR20090078478A - Light emitting device - Google Patents

Abstract

A light emitting device is provided to diversify the color reproducibility and the luminance without changing the number of driver circuits. A light emitting device comprises a light emitting device package and a driving part. The light emitting device package has light emitting devices(21,22) and a fluorescent substance(30). The light emitting device radiates the lights of the first and second colors. The fluorescent substance is arranged on the light emitting devices. The fluorescent substance is excited and radiated by receiving at least one of the lights of the first and second colors from the light emitting devices. The light emitted from the fluorescent substance emits the light of the third color. The driving part operates the light emitting devices.

Description

Light emitting device

The present invention relates to a light emitting device, and more particularly, to a light emitting device capable of efficiently driving a light emitting device package.

Light Emitting Diodes (LEDs) are well-known semiconductor light emitting devices that convert current into light.In 1962, red LEDs using GaAsP compound semiconductors were commercialized, along with GaP: N series green LEDs. It has been used as a light source for display images of electronic devices, including.

The wavelength of light emitted by such LEDs depends on the semiconductor material used to make the LEDs. This is because the wavelength of the emitted light depends on the band-gap of the semiconductor material, which represents the energy difference between the valence band electrons and the conduction band electrons.

Gallium nitride compound semiconductors (Gallium Nitride (GaN)) have high thermal stability and wide bandgap (0.8 to 6.2 eV), which has attracted much attention in the development of high-power electronic components including LEDs.

One reason for this is that GaN can be combined with other elements (indium (In), aluminum (Al), etc.) to produce semiconductor layers that emit green, blue and white light.

In this way, the emission wavelength can be adjusted to match the material's characteristics to specific device characteristics. For example, GaN can be used to create white LEDs that can replace incandescent and blue LEDs that are beneficial for optical recording.

Due to the advantages of these GaN-based materials, the GaN-based LED market is growing rapidly. Therefore, since commercial introduction in 1994, GaN-based optoelectronic device technology has rapidly developed.

The brightness or output of the LED using the GaN-based material as described above is large, the structure of the active layer, the light extraction efficiency to extract light to the outside, the size of the LED chip, the type and angle of the mold (mold) when assembling the lamp package , Fluorescent material and the like.

SUMMARY OF THE INVENTION The present invention provides a light emitting device including a light emitting device package and a driving unit, wherein the number of driving circuits does not increase even when the divided driving area of the light emitting device chip is increased, and the light emission of which color reproducibility and brightness can be adjusted. To provide a device.

As a first aspect for achieving the above technical problem, the present invention, at least two or more light emitting devices for emitting light of the first and second colors different from each other, and positioned on the light emitting device and the first color and second A light emitting device package including a phosphor which is excited by light of at least one color of color and emits light, and the emitted light is mixed with light of the first and second colors to emit light of a third color; ; And a driving unit for simultaneously driving the light emitting elements for emitting the light of the first color and the second color.

As a second aspect of the present invention, there is provided a light emitting device package including at least two light emitting devices emitting green and blue light, and a red phosphor located on the light emitting devices; And a driving unit for simultaneously driving the light emitting devices for emitting the green and blue light.

The present invention can prevent an increase in the number of driving units of the light emitting device, and can configure a minimum driving unit, which can greatly reduce the area and cost of the driving unit, and can improve the color reproducibility of the light emitting device. There is an effect that can adjust the brightness of.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

While the invention allows for various modifications and variations, specific embodiments thereof are illustrated by way of example in the drawings and will be described in detail below. However, it is not intended to be exhaustive or to limit the invention to the precise forms disclosed, but rather the invention includes all modifications, equivalents, and alternatives consistent with the spirit of the invention as defined by the claims.

The terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, but such elements, components, regions, layers and / or regions may be It will be understood that it should not be limited by terminology.

In recent years, the light emitting device has been increasing its application from the existing small display device to the lighting and large display market. In the case of using a light emitting device, lighting can freely change the color temperature to create an atmosphere suitable for a place, and a large display can use advantages such as low power consumption, high color reproduction and contrast ratio.

In order to take advantage of these advantages, a driver for a light emitting device is needed. In order to control the brightness of the light emitting device, the light emitting device driver controls current in a manner using a switching regulator.

As shown in FIG. 1, the overall configuration of the light emitting element driver includes a driver 4 for driving red (1), green (2), and blue (3) light emitting elements, and the driver. It consists of a control part 5 which transmits a drive signal to (4), and a power supply part 6.

As can be seen in FIG. 2, the driving units 4 of the red (1), green (2), and blue (3) light emitting elements require individual driving units 4a, 4b, and 4c, respectively.

However, when the light emitting device modules are arrayed and dividedly driven, the number thereof increases in proportion to the divided driving region. For example, if there are no divided regions, three light emitting element driving units are provided for the red, green, and blue light emitting elements. This also increases the area and cost of the driver in the product, leading to higher overall costs.

In order to solve this problem, one light emitting device chip among the red, green, and blue light emitting device chips may be replaced with a phosphor in consideration of color stability according to current and temperature. For example, the red light emitting device chip may be removed and replaced with a red phosphor.

3 and 4 are diagrams illustrating an example of a light emitting device package. The molding unit is formed by using primary light of blue light and green light emitted from the blue and green light emitting devices 21 and 22 positioned on the substrate 10. A white semiconductor light emitting device is shown in which a red phosphor 30 contained in 40 is excited, and white light can be emitted by mixing of secondary light emitted from light emitting elements 21 and 22 at this time.

However, the light emitting devices 21 and 22 also increase as the number of divided regions increases. One way to overcome this is to use a UV light emitting device that emits UV light and phosphors that emit red (R), green (G), and blue (B), or blue light emitting devices and red and green phosphors. Low light emission efficiency may be a problem when using a light emitting device, and when using a blue light emitting device, there is a technical difficulty that the color reproduction ratio is only 85% compared to NTSC.

Accordingly, the present invention provides an embodiment of the present invention having a color reproducibility of 110% or more and greatly reducing the number of driving portions even when the number of divided regions is increased.

<Example>

Hereinafter, an embodiment of a light emitting device that is attracting attention with respect to color reproduction and division driving will be described. Such a light emitting device may be applied to the light emitting device backlight unit portion, and provides an advantageous form of connection of the light emitting device chip in the light emitting device package. A detailed description will be given with reference to the drawings.

FIG. 5 illustrates a method for simultaneously driving the blue and green light emitting devices 21 and 22 in the light emitting device manufactured by using the blue and green light emitting devices 21 and 22 and the red phosphor 30 as shown in FIGS. 3 and 4. The configuration is shown.

That is, the blue and green light emitting device chips 21 and 22 are mounted on the first electrode 51 and electrically connected to the second electrode 52 through the first wire 61. At this time, since the first electrode 51 and the second electrode 52 are separated from each other, the two light emitting device chips 21 and 22 are connected by connecting two second electrodes 52 to each other through the second wire 62. ) Can be connected in series with each other.

As such, since the two light emitting device chips 21 and 22 are connected to each other, two or two kinds of the light emitting device chips 21 and 22 may be simultaneously driven using one driver 100 (see FIG. 10). Since the red phosphor 30 emits light by driving the blue and green light emitting device chips 21 and 22 as described above, white light emission is possible.

The two light emitting devices may be connected to each other through a wiring 63 of a circuit board and driven simultaneously.

6 and 7 illustrate an embodiment in which the light emitting device chip connection structure is improved to simplify the structure.

That is, the blue and green light emitting device chips 21 and 22 are directly connected in series as illustrated in FIG. 6, or in parallel with each other as illustrated in FIG. 7.

As shown in FIG. 6, the first electrode 53 and the second electrode 54 connected to the blue light emitting element 21 and the green light emitting element 22 are positioned on one surface of the substrate 10, respectively. The light emitting elements 21 and 22 are connected to each other in series by the third wire 64.

In addition, in FIG. 7, the structure of FIG. 6 is the same as the structure of FIG. 6, but the blue light emitting element 21 and the green light emitting element 22 positioned on the substrate 10 are connected in parallel with each other by the fourth wire 65. It is shown.

The light emitting device chips 21 and 22 having the above-described structure and the package are driven using a current driving method. For example, if the individual chip rated current is 20 mA, 20 mA (Vf: 3.2 V) should be applied for split driving, respectively, but in the package structure shown in this embodiment, as shown in Figs. When the device chips 21 and 22 are connected in series, only 20 mA (Vf: 6.4 V) may be applied to drive the devices.

In addition, as shown in FIG. 7, when the light emitting device chips 21 and 22 are connected in parallel, only 40 mA (Vf: 3.2 V) may be applied for driving. In this way, three or two driving units are not required, and only one driving unit can be driven by changing the current and voltage levels, thereby simplifying and simplifying the structure of the light emitting device.

The cross section of the package structure as described above is as shown in FIG. That is, the first electrode 53 and the second electrode 54 are positioned on the substrate 10, and the blue light emitting element 21 and the green light emitting element 22 are each first electrode through the first wire 61. 53 and the second electrode 54, the blue light emitting element 21 and the green light emitting element 22 may be connected in series or in parallel with each other through the third wire (64, or fourth wire; 65). have.

On the light emitting elements 21 and 22, a molding part 40 made of resin is positioned, and a red phosphor 30 is distributed in the molding part 40. In some cases, the phosphor 30 may not be distributed in the molding part 40, and a separate phosphor layer (not shown) may be positioned above or below the molding part 40.

In some cases, the light emitting device and the phosphor may be mixed with each other instead of the above-described blue and green light emitting devices, and the red phosphor to form white light. Combination is also possible, of course.

Meanwhile, as illustrated in FIG. 9, optical characteristics such as color coordinates and luminance desired in the package may be adjusted by adjusting the size of the light emitting device chips 21 and 22. The size of the light emitting device chips 21 and 22 is generally divided into small, middle, and large, as shown in Table 1 below when manufacturing the light emitting device chip, and an example of the actual size thereof may be summarized as follows. .

As shown in Table 1, the rated current conditions may be different for each light emitting device chip size. This directly affects the optical characteristics of the chip.

When the package is manufactured using the characteristics of the light emitting device chip, for example, the green and blue light emitting device chip sizes are used equal to 0.5 × 0.5, respectively, and the size of the blue light emitting device chip 21 is not changed. When the size of the green light emitting device chip 22 is changed to 0.7 × 0.7 and driven at a rated current of 150 mA or less, the luminance and color coordinates of the light emitting device may vary greatly. Thus, by analyzing and applying the luminance and color coordinate correlation for each combination of sizes by using the size difference of the light emitting device chip, it is possible to adjust the desired target specification, that is, the color coordinate and the luminance.

Using the light emitting device package as described above, as shown in FIG. 10, the driving unit structure of the light emitting device package may be simplified. That is, the driver 100 capable of simultaneously driving the blue light emitting element 21 and the green light emitting element 22 may be used. The control unit 110 and the power supply unit 120 may be connected to the driving unit 100.

Due to the structure and the driving unit, the man-hour and cost of the driving unit can be lowered, and the driving method using the package and the driving unit can also be simplified.

The above embodiment is an example for explaining the technical idea of the present invention in detail, and the present invention is not limited to the above embodiment, various modifications are possible, and various embodiments of the technical idea are all protected by the present invention. It belongs to the scope.

1 is a block diagram illustrating an example of a light emitting device package driver.

FIG. 2 is a block diagram illustrating details of the light emitting device package driver of FIG. 1.

3 is a plan view illustrating an example of a light emitting device package.

4 is a cross-sectional view of FIG. 3.

5 is a plan view illustrating a first embodiment of a light emitting device package.

6 is a plan view illustrating a second embodiment of a light emitting device package.

7 is a plan view illustrating a third embodiment of a light emitting device package.

8 is a cross-sectional view of FIG. 6.

9 is a plan view illustrating a fourth embodiment of a light emitting device package.

10 is a block diagram illustrating another example of a light emitting device package driver.

Claims (10)

At least two light emitting devices for emitting light of different first and second colors, and excited on at least one of the light of the first and second colors and positioned on the light emitting device to emit light A light emitting device package including a phosphor that is mixed with the light of the first color and the second color to emit light of a third color; And a driving unit for simultaneously driving the light emitting elements for emitting the light of the first color and the second color. The light emitting device according to claim 1, wherein the first color and the second color are blue and green. The light emitting device of claim 1, wherein the phosphor is a phosphor that emits red light, and the third color is white light. The light emitting device of claim 1, wherein the light emitting device emitting light of the first color and the light emitting device emitting light of the second color are connected in series or in parallel with each other. The light emitting device of claim 1, wherein the light emitting device emitting light of the first color and the light emitting device emitting light of the second color are different in size. 2. The light emitting device of claim 1, wherein the light emitting element is current driven. The light emitting device of claim 1, wherein the phosphor is included in a molding part positioned on the light emitting element. The light emitting device of claim 1, wherein the light emitting element is electrically connected to an electrode disposed on a substrate. The light emitting device of claim 8, wherein the electrodes are connected to each other on an upper surface and a lower surface of the substrate. A light emitting device package including at least two light emitting devices emitting green and blue light, and a red phosphor positioned on the light emitting devices; And a driving unit for simultaneously driving the light emitting elements emitting the green and blue light.

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