Patent Application
20130170245
This application claims the benefit of Korean Patent Application No. 10-2011-0147248, filed on Dec. 30, 2011, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field
Embodiments relate to a lighting device. More particularly, embodiments relate to a lighting device for improving light distribution uniformity.
2. Description of the Related Art
A light emitting diode (LED) is a semiconductor device that emits light in a direction of a current flow. In other words, the LED is an electronic part that converts electric energy to light energy. The LED is a p-n junction diode, including a gallium arsenide (GaAs) and gallium nitride (GaN) light semiconductor.
Recently, a blue LED and an ultraviolet (UV) LED have been developed using a nitride having excellent physical and chemical characteristics. Since white light or other forms of monochromatic light can be produced using the blue LED or the UV LED and phosphor substances, a range of applications for the LED is expanding.
The LED has a relatively long life, small size, light weight, high directivity of light, and low-voltage operability. Furthermore, the LED is resistant against impact and vibration. The LED also does not need preheating and complicated driving. Therefore, the LED is applicable to many fields. For example, the range of applications for the LED has recently expanded to small-size lighting for a mobile terminal, general lighting for indoors and outdoors, vehicle lighting, a backlight unit for a large-area liquid crystal display (LCD), etc.
As the LED achieves a high output of light and a high efficiency, a lighting device employing the LED has been replacing general conventional lighting devices. However, an optical system is necessary, because the LED has a different type of light distribution, when compared to conventional lighting devices. In a case of a straight-tube fluorescent lamp, it is very difficult to embody characteristics of a circular surface light source with the LED.
An aspect of the embodiments provide a lighting device capable of embodying characteristics of a uniform and circular surface light source using a light emitting diode (LED).
Another aspect of the embodiments provides a lighting device with improved light distribution uniformity.
Still another aspect of the embodiments provides a lighting device which is applicable to various conditions of light distribution and improved in a degree of freedom in design.
According to an aspect of the embodiments, there is provided a lighting device including a device main body, a light emitting diode (LED) which is provided to at least one of both ends of an inside of the device main body, and a light guide member which is disposed between the both ends of the device main body to uniformly distribute light emitted from the LED to the outside, wherein a refractive index of the light guide member is reduced in a direction away from the LED.
The light guide member may be formed by bonding a plurality of light guide materials having different refractive indices.
For example, the LED may be disposed at the both ends of the device main body. The light guide member may include a first light guide material which is disposed at each end of the lighting device to receive the light emitted from the LED, and a second light guide material, disposed between the first light guide material disposed at each end of the lighting device, to be bonded to the first light guide material at each end of the lightning device, the second light guide material has a lower refractive index than the first light guide materials.
Alternatively, the LED may be disposed at the at least one end of the device main body, and the light guide member may include a first light guide material which is disposed at one end of the lighting device to receive the light emitted from the LED, a second light guide material which is bonded to one end of the first light guide material, the second light guide material having a lower refractive index than the first light guide materials, and a third light guide material bonded to an end of the second light guide material and disposed at an opposite end of the device main body, the third light guide material has a lower refractive index than the second light guide materials.
The light guide member may include an uneven surface portion disposed on a surface to diffuse or reflect the light to increase light distribution efficiency.
The light guide member may include at least one of a bubble body and a reflection body disposed at an inside of the light guide member to diffuse or reflect the light to increase light distribution efficiency.
The light guide member may include at least one of a bubble body and a reflection body disposed at an inside of the light guide member to diffuse or reflect light from the LED to increase light distribution efficiency of the light guide member, and at least one of the bubble body and the reflection body may be configured to have a density varying according to positions of the light guide member so that a refractive index is varied according to the positions of the light guide member.
The density of the at least one of the bubble body and the reflection body may be reduced in a direction away from the LED.
The light guide member may be sloped to have a reduced thickness in the direction away from the LED such that an effective refractive index is reduced in a direction away from the LED.
The light guide member may be provided in a conical shape or a polygonal pyramid shape.
The device main body may include a fluorescent tube which is configured to receive the LED and the light guide member inside, and a support member which is connected to the both ends of the fluorescent tube to support the light guide member. Here, the LED may be configured to emit monochromatic light, and a phosphor converts the monochromatic light to white light.
The fluorescent tube may include the phosphor. Alternatively, the phosphor may be provided in a layer form on a surface of the fluorescent tube.
According to another aspect of the embodiments, there is provided a lighting device including a device main body, a light emitting diode (LED) which is provided in at least one end of an inside of the device main body, and a light guide member which is disposed between both ends of the device main body to uniformly distribute light emitted from the LED to the outside. The device main body may include a fluorescent tube configured to receive the LED and the light guide member inside and provided with a phosphor for converting monochromatic light to white light, and a support member connected to the both ends of the fluorescent tube to support the light guide member.
The fluorescent tube may include the phosphor. Alternatively, the phosphor may be provided in form of a layer on a surface of the fluorescent tube.
According to a further aspect of the embodiments, there is provided a lightning device including a light emitting diode (LED), a light guide member which is configured to uniformly distribute light, an elongated cylinder which is configured to include the LED and the light guide member, a first support member which is connected to one end of the elongated cylinder to support the light guide member, and a second support member which is connected to an opposite end of the elongated cylinder as compared to the one end of the elongated cylinder, wherein the LED is disposed at the one end of the elongated cylinder.
In a lighting device according to embodiments, a refractive index of a light guide member is reduced in a direction away from an LED. Therefore, light may be evenly distributed throughout the light guide member. Accordingly, uniformity of light distribution of the lighting device may be increased. In particular, when the lighting device is applied to a direct-type fluorescent lamp, characteristics of a circular surface light source may be easily achieved.
According to embodiments, the lighting device includes the light guide member formed by bonding a plurality of materials having different refractive indices. Therefore, a light guide member, in which a refractive index is varied depending on positions, may be easily manufactured.
The lighting device according to embodiments includes an uneven surface portion formed on a surface of the light guide member, or includes a bubble body or a reflection body provided in the light guide member. Therefore, using diffusion and reflection of light, light distribution characteristics of the light guide member may be enhanced.
In addition, in the lighting device according to embodiments, the light guide member having various refractive indices, depending on positions, may be easily manufactured by adjusting a density of the bubble body or the reflection body provided in the light guide member.
The lighting device according to embodiments is structured such that a thickness of the light guide member is reduced, in a sloping manner in a direction away from the LED. Therefore, an effective refractive index of the light guide member may be easily varied according to a position. In particular, the effective refractive index may be easily controlled by adjusting an angle of a slope formed on the surface of the light guide member according to the position, or by varying gas injected to a space between the light guide member and a fluorescent tube.
Furthermore, the lighting device according to embodiments includes an LED that emits monochromatic light. The fluorescent tube, that includes a phosphor, converts the monochromatic light into white light. Accordingly, separation of white light from the light guide member may be prevented. As a result, stability of the light distribution may be increased.
These and/or other aspects, features, and advantages of the embodiments will become apparent and more readily appreciated from the following description of exemplary embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. However, aspects are not limited by the exemplary embodiments.
Referring to
The device main body 110 may include a fluorescent tube 112 and a support member 114.
The fluorescent tube 112 has a tubular shape to receive the LED 120 and the light guide member 130. Hereinafter, the fluorescent tube 112 will be described to have a form of an elongated cylinder, although a form of the tube is not limited thereto. The shape of the fluorescent tube 112 may be varied according to design conditions of the lighting device 100.
The fluorescent tube 112 may be made of a transparent material to allow transmission of light emitted from the light guide member 130. For example, the fluorescent tube 112 may be made of transparent glass or plastic.
A phosphor (not shown) to convert monochromatic light of the LED 120 into white light may be provided in the fluorescent tube 112. In other words, when the LED 120 is designed to generate monochromatic light, as will be described hereinafter, the phosphor of the fluorescent tube 112 may generate white light through a reaction with the monochromatic light emitted from the light guide member 130.
When the phosphor is disposed as aforementioned, the phosphor and the LED 120 may be set apart from each other by a predetermined distance. Accordingly, damage to the phosphor by heat of the LED 120 may be prevented. Also, the light passed through the light guide member 130 may be more uniformly distributed as passing through the fluorescent tube 112. Furthermore, since a light beam emitted through the fluorescent tube 112 is uniformly distributed, a hot spot of the lighting device 100 may not be generated.
Light beams having different color temperatures may be provided by controlling a mixture ratio of the phosphor. For example, when the mixture ratio is controlled such that opposite ends of the fluorescent tube 112 have a higher color temperature than a middle part a light beam of the lighting device 100 may have an overall warm and mild feeling. Here, the color temperature is controlled by the mixture ratio of the phosphor because the LED 120 and the phosphor are separated from each other. A phosphor surface of the fluorescent tube 112 is disposed over an entire phosphor surface of the LED 120.
The phosphor may be included in the fluorescent tube 112. In other words, the fluorescent tube 112 may be shaped after mixing the phosphor with a raw material of the fluorescent tube 112. Accordingly, the phosphor and the fluorescent tube 112 may be integrally formed.
Alternatively, the phosphor may be disposed in a layer form on a surface of the fluorescent tube 112. In other words, after the fluorescent tube 112 is made of a material not containing the phosphor, the phosphor may be applied on the surface of the fluorescent tube 112. Accordingly, the phosphor may be formed as a thin layer applied on the surface of the fluorescent tube 112.
Hereinafter, although the embodiment will be described such that the phosphor is included in the fluorescent tube 112, the phosphor is neither shown in the drawings nor assigned a reference numeral.
The support member 114 may support the LED 120 and the light guide member 130. In other words, the support member 114 may be connected to opposite ends of the fluorescent tube 112. The LED 120 or the light guide member 130 may be connected to the support members 114. The support members 114 and the fluorescent tube 112 may form a hermetic space for receiving the LED 120 and the light guide member 130.
The support members 114 may each include a power pin 116 for supplying external power to the LED 120. In other words, power input through the power pin 116 may be transmitted to the LED 120. In addition, the power pin 116 may fix the lighting device 100, as a straight-tube fluorescent lamp, to an external structure.
Referring to
Various types of light source may be used as the LED 120. For example, the LED 120 may be an LED package module that emits monochromatic light or white light. In particular, an LED package module emitting monochromatic light may be used. Hereinafter, the embodiment will be described as using an LED package module emitting a blue ray or an ultraviolet (UV) ray as the LED 120, so that the monochromatic light of the LED 120 is converted to white light by the phosphor of the fluorescent tube 112.
When the LED package module emitting the monochromatic light is used, the light of the LEDs 120 may be prevented from being separated into various types of monochromatic light due to a prism effect of the light guide member 130. Thus, the LED package module emitting the monochromatic light may enable flexible arrangement and processing of the light guide member 130 without causing light separation.
Conversely, when an LED package module emitting white light is used, the white light may be separated into various types of monochromatic light due to the prism effect by being refracted, diffused, or reflected by the light guide member 130. As a result, light distribution efficiency of the lighting device 100 may be reduced.
Referring to
The light guide member 130 may be formed of a transparent material for distribution of the light of the LEDs 120. For example, the light guide member 130 may be made of transparent glass or a plastic material.
The light guide member 130 may be configured to have a refractive index reduced in a direction A away from the LEDs 120. In other words, since the refractive index of the light guide member 130 is varied according to positions of the light guide member 130, illumination of the light distributed throughout the light guide member 130 may be controlled to be uniform. In particular, since light of the LED package module has an extremely high property of straightness, a light amount refracted by the light guide member 130 may be increased by configuring the light guide member 130 to have a higher refractive index at positions closer to the LEDs 120.
By varying the refractive index of the light guide member 130 according to positions, light distribution efficiency of the lighting device 100 may be increased. Various examples of the light guide member 130 are illustrated in
Referring to
The first light guide materials 132a may be directly connected to or disposed adjacent to the LEDs 120 disposed at the opposite ends of the fluorescent tube 112. Opposite ends of the second light guide material 132b may be bonded to the first light guide materials 132a. However, the light guide member 132 is not limited to include the first light guide materials 132a and the second light guide material 132b. According to a design and conditions of the lighting device 100, the refractive index, a number, a shape of a bonding surface of the light guide materials 132a and 132b may be variably controlled.
Referring to
The light guide member 134 shown in
The uneven surface portion 135 may be formed on the surface of the light guide member 134 by various methods. For example, the surface of the light guide member 134 may be directly processed, or shaped into the uneven surface portion 135 using a mold including the uneven surface portion 135. Also, the uneven surface portion 135 may be separately formed and attached to the surface of the light guide member 134.
Referring to
A shape, a size, and a distance of the bubble body 137 or the reflection body may be varied according to the design or the conditions of the lighting device 100. For example, the bubble body 137 or the reflection body may be provided in a spherical, conical or pyramidal, or pillar shape, and may be distributed in the light guide member 136 in various patterns.
The light guide member 136 shown in
The operation of the lighting device 100 structured as aforementioned will now be described. Hereinafter, the light guide member 130 shown in
First, when power is supplied to the lighting device 100, the power is transmitted to the LEDs 120 disposed at opposite ends of the fluorescent tube 112 through the power pins 116, thereby operating the LEDs 120.
The LEDs 120 emit monochromatic light through the light guide member 130. The light from the LEDs 120 may be incident to an inside of the light guide member 130 through the opposite ends of the light guide member 130.
The light from the LEDs 120 may pass through the first light guide materials 132a disposed at the opposite ends of the light guide member 130, during which the first light guide materials 132a may refract the light from the LEDs 120 by a first refractive index toward the opposite ends of the fluorescent tube 112.
After passing through the first light guide materials 132a, the light may pass through the second light guide material 132a disposed in the middle part of the fluorescent tube 112, during which the second light guide material 132b may refract the light passed through the first light guide materials 132a by a second refractive index toward the middle part of the fluorescent tube 112.
Since the first refractive index is greater than the second refractive index, refraction of the high-straightness light emitted from the LEDs 120 may be efficiently performed. During the refraction, straightness of the light being transmitted to the first light guide materials 132a may be reduced. Accordingly, although the second refractive index of the second light guide material 132b is smaller than the first refractive index, the second light guide material 132b may refract the light by almost the same degree as the first light guide materials 132a.
The light emitted from the light guide member 130 to the fluorescent tube 112 may be emitted by uniform illumination from the entire part of the light guide member 130. As passing through the fluorescent tube 112, the light may be converted into white light by the phosphor.
Since the light emitted from the LEDs 120 is monochromatic light, separation of the light into various types of monochromatic light during refraction by the light guide member 130 may be prevented. Accordingly, stability of light distribution and a degree of freedom in design of the lighting device 100 may be increased. Furthermore, when the light guide member 130 is further provided with the uneven surface portion 135 of
Referring to
In other words, at least one of the bubble body 237 and the reflection body for diffusing or reflecting the light of the LEDs 120 may be provided in the light guide member 230 to increase light distribution efficiency of the light guide member 230. The bubble body 237 and the reflection body are almost the same structure as the bubble body 137 and the reflection body described with reference to
When the density of the bubble body 237 is increased, refraction efficiency of the light may be increased. When the density of the bubble body 237 is reduced, refraction efficiency of the light may be reduced. Therefore, the bubble body 237 may be configured to have the density reduced in a direction toward the LEDs 120.
The light guide member 230 shown in
Referring to
In other words, the light guide member 330 may be configured such that an effective refractive index is reduced in a direction away from the LEDs 120. The effective refractive index of the light guide member 330 may be a mean value of refractive indices of all positions from the LEDs 120 to the fluorescent tube 112. In other words, the light from the LEDs 120 may be first refracted by a first refractive index when passing through the light guide member 330, and secondly refracted by a second refractive index when passing through a space between the light guide member 330 and the fluorescent tube 112. The effective refractive index refers to the mean value of the first refractive index and the second refractive index. The effective refractive index may be varied according to gas injected in the space formed by the fluorescent tube 112 and the support members 114.
Since the thickness of the light guide member 330 is different according to the distance to the LEDs 120, the distance between the light guide member 330 and the fluorescent tube 112 is also varied. Accordingly, the effective refractive index may be varied according to positions of the light guide member 330. However, in the lighting device 100 shown in
As shown in
A vertex portion of the light guide member 330 may be disposed to be far from the LEDs 120. A bottom surface portion of the light guide member 330 may be directly connected to or disposed adjacent to the LEDs 120. Here, vertex portions of the first light guide member 332 and the second light guide member 334 may be interconnected or separated by a predetermined distance.
The light from the LEDs 120 may be refracted by slant surfaces 332a and 334a of the light guide member 330. In other words, the slant surfaces 332a and 334a may correspond to refraction surfaces for refracting the light to the fluorescent tube 112.
Since the same or similar reference numerals as illustrated in
Referring to
Therefore, a light guide member 430 according to the present embodiment may include a first light guide material 432 disposed at one end of the fluorescent tube 112 of a device main body 410 to receive light of the LED 120, a second light guide material 434 bonded to an end of the first light guide material 432 and configured to have a lower refractive index than the first light guide material 432, and a third light guide material 436 disposed at the opposite end of the fluorescent tube 112 and configured to have a lower refractive index than the second light guide material 434.
A support member 114′, different from the support member 114 shown in
Although a few exemplary embodiments have been shown and described, embodiments are not limited to the described exemplary embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these exemplary embodiments without departing from the principles and spirit of the embodiments, the scope of which is defined by the claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2011-0147248 | Dec 2011 | KR | national |
