Patent Application
20150338057
The present invention relates to a side-emitting light emitting diode (LED) lens for emitting light emitted from an LED from a side surface of the lens, and a backlight unit and display device including the same.
In general, a display device used as a monitor of a computer, a television (TV), or the like includes a liquid crystal display (LCD). In this regard, the LCD is not capable of emitting light and thus requires a separate light source.
A plurality of fluorescent lamps such as a cold cathode fluorescent lamp (CCFL) or a plurality of light emitting diodes (LEDs) are used as a light source for an LCD, and the light source is included in a back light unit (BLU) together with a light guide plate, a plurality of optical sheets, a reflector, and so on.
Recently, among these light sources, an LED has attracted attention as a next generation light source due to low power consumption, excellent durability, and low manufacturing costs. However, when an LED is used as a light source, since light has a tendency to be intensively emitted to a narrow region, there is a need to uniformly distribute light to a wide region in order to apply the LED to a surface light source such as a display device.
Accordingly, recently, research has been actively conducted into an LED lens for performing this function. In this regard, “SIDE EMITTING LED LENS” is disclosed as a representative prior art in U.S. Pat. No. 6,679,621.
The side emitting LED lens is a lens for emitting light emitted from an LED from a side surface of the lens and includes a reflective surface for reflecting light that is emitted from the LED and incident on the lens to a side surface of the lens. The reflective surface may be formed by reflective-coating an upper surface or formed to total-reflect the incident light by the upper surface.
However, when the reflective surface is formed by reflective-coating an upper surface, manufacturing costs are increased in that a lens is formed of a transparent material via injection molding and then the upper surface is separately reflective-coated, and when the upper surface is formed to total-reflect incident light without reflective-coating, a significant amount of light is not total-reflected off the upper surface and is emitted upwards through the upper surface.
An object of the present invention devised to solve the problem lies in a side-emitting light emitting diode (LED) lens for minimizing the amount of light emitted upwards through an upper surface rather than being total-reflected at the upper surface even if the upper surface is formed to total reflect light incident thereon without reflection coating when a reflective surface is formed.
The object of the present invention can be achieved by providing a side-emitting light emitting diode (LED) lens for emitting light emitted from an LED chip for emitting light as a flat source towards a side surface, including a lower surface including an incident surface with light emitted from the LED chip thereon, an upper surface formed to total-reflect directly incident light among light beams incident on the incident surface, and a side surface for connecting the lower surface and the upper surface and formed to emit directly incident light among light total-reflected by the upper surface and light incident on the incident surface, out of the lens, wherein the upper surface is formed to total-reflect light that is emitted from an end point of a light emitting surface of the LED chip, positioned at the same side as an arbitrary point on the upper surface based on an optical axis of the LED chip, and incident on the arbitrary point on the upper surface, towards the side surface
In another aspect of the present invention, provided herein is a side-emitting light emitting diode (LED) lens for emitting light emitted from an LED chip for emitting light as a volume source towards a side surface, including a lower surface including an incident surface with light emitted from the LED chip thereon, an upper surface formed to total-reflect directly incident light among light beams incident on the incident surface, and a side surface for connecting the lower surface and the upper surface and formed to emit directly incident light among light total-reflected by the upper surface and light incident on the incident surface, out of the lens, wherein the upper surface is formed to total-reflect light that is emitted from a lower end point of the side surface of the LED chip, positioned at the same side as an arbitrary point on the upper surface based on an optical axis of the LED chip, and incident on the arbitrary point on the upper surface, towards the side surface.
In another aspect of the present invention, provided herein is a back light unit (BLU) using a light emitting diode (LED) chip as a light source, including the aforementioned LED lens on the LED chip.
In another aspect of the present invention, provided herein is a display device using a light emitting diode (LED) chip as a light source, including the aforementioned LED lens on the LED chip.
When a side-emitting LED lens configured above according to the present invention is formed such that an upper surface total-reflects light incident on an inner part of the lens towards a side surface, a light source for light emitted from an LED chip is formed to be considered as a flat source or a volume source instead of one point source, thereby minimizing the amount of light that is emitted upwards through the upper surface.
When the side-emitting LED lens according to the present invention is formed such that an upper surface total-reflects light incident on an inner part of the lens towards a side surface, a shape of an incident surface on which light emitted from the LED chip and incident on the inner part of the lens is considered, thereby minimizing the amount of light emitted upwards through the upper surface.
Exemplary embodiments of the present invention are described in detail so as for those of ordinary skill in the art to easily implement with reference to the accompanying drawings.
As the invention allows for various changes and modifications, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to particular modes of practice, and it is to be appreciated that all changes, equivalents, and substitutes that do not depart from the spirit and technical scope of the present invention are encompassed in the present invention.
For clarity, thicknesses and sizes of components are exaggerated in the drawings, and accordingly the present invention is not limited by relative thicknesses and sizes illustrated in the accompanying drawings.
The present invention relates to a side-emitting light emitting diode (LED) lens for minimizing the amount of light emitted upwards through an upper surface rather than being total-reflected at the upper surface even if the upper surface is formed to total reflect light incident thereon without reflection coating when a reflective surface for emitting light emitted from an LED chip towards a side surface is formed. In addition, the present invention also relates to a back light unit (BLU) and a display device, including the LED lens. However, other configurations of the BLU and display device except for the LED lens may be easily implemented by one of ordinary skill in the art, and thus a detailed description thereof will be omitted in the specification.
Referring to
The lower surface 20 may include an incident surface 100 on which light emitted from an LED chip 11 installed on a circuit board 9 is incident, and the incident surface 100 may be formed as an internal surface of a groove portion 21 formed in a central portion of the lower surface 20. As such, as illustrated in
The upper surface 30 is formed so as to total-reflect light L1 incident directly on the upper surface 30 among light beams that are emitted from the LED chip 11 and incident on an inner part of the lens 10 through the incident surface 100 towards the side surface 40, and the side surface 40 is formed so as to emit light L2 total-reflected from the upper surface 30 out of the lens 10. In particular, the side surface 40 is formed so as to emit light L3 incident directly on the side surface 40 among light beams, which are emitted from the LED chip 11 and incident on an inner part of the lens 10 through the incident surface 100, out of the lens 10, which will be described in detail.
In addition, the side surface 40 may be increasingly inclined upwards by a predetermined angle θ based on an optical axis 12 or increasingly inclined downwards by the predetermined angle θ based on the optical axis 12. For example, as illustrated in
In general, an LED lens may be formed of a transparent material with excellent transmittance such as glass, methylmethacrylate, polymethylmethacrylate (PMMA), polycarbonate (PC), and poly ethylen terephthalate (PET) and manufactured as one body via injection molding. In this regard, although a plurality of molds is required to manufacture a lens via injection molding, the lens 10 according to the present invention is configured in such a way that the side surface 40 is expanded in one direction of upwards or downwards directions based on the optical axis 12, and thus injection molding may be possible by only two molds such as a lower mold and an upper mold, and the upper mold and the lower mold may be easily separated upwards and downwards, respectively.
In addition, the lens 10 according to the present invention may further include a leg 50 that extends downwards from a predetermined position of the lower surface 20 and is coupled onto the circuit board 9 to support the lens 10.
As described above, the upper surface 30 may be formed to total-reflect the directly incident light L1 among light beams that are emitted from the LED chip 11 and incident on the incident surface 100 towards the side surface 40 and will be described in detail.
As illustrated in
However, since the side-emitting LED lens 10 according to the present invention is not formed with a much greater volume than the LED chip 11, when the side-emitting LED lens 10 is formed in such a way that the upper surface 30 total-reflects only light emitted from the first reference point P1 assuming that light emitted from the LED chip 11 is one point source like a conventional lens, a significant amount of light is accordingly emitted upwards through the upper surface 30 rather than being total-reflected off the upper surface 30.
Accordingly, when the side-emitting LED lens 10 according to the present invention is formed such that the upper surface 30 total-reflects directly incident light L1, a light source for light emitted from the LED chip 11 may be formed to be considered as a flat source or a volume source instead of one point source, thereby minimizing the amount of light that is emitted upwards through the upper surface 30 rather being total-reflected off the upper surface 30. Here, whether a light source for the light emitted from the LED chip 11 is considered as a flat source or a volume source may be determined according to a shape of the LED chip 11, which will be described below.
Referring to
A condition of the upper surface 30 will now be described with reference to 1/√(n2−1) (hereinafter, referred to as ‘condition 1’).
That is,
ΔR/(RΔα)1/√(n2−1) condition 1:
(Here, α: angle between the optical axis 12 and the light L that is emitted from the second reference point P2 and reaches the arbitrary point P, Δα: increment in α, R: distance between the second reference point P2 and the arbitrary point P on the upper surface 30, ΔR: increment in R with respect to Δα, and n: refractive index of a material for forming the lens 10)
As described above, when the upper surface 30 is configured to satisfy the condition 1, almost all light beams that are emitted from the light emitting surface 112 of the LED chip 11 and incident directly on an inner part of the lens 10 through the incident surface 100 may be total-reflected towards the side surface 40, thereby minimizing the amount of light emitted upwards through the upper surface 30.
The condition 1 is satisfied when a shape of the incident surface 100 is not considered. In reality, since the light emitted from the LED chip 11 is refracted according to the shape of the incident surface 100 and incident on the inner part of the lens 10, the upper surface 30 may be formed in consideration of the shape of the incident surface 100 in order to minimize the amount of light emitted upward rather than being total-reflected off the upper surface 30. To this end, the condition 1 needs to be defined with respect to an angle between the optical axis 12 and light L′ obtained by refracting the light L by the incident surface 100 instead of the L that is emitted from the second reference point P2 and reaches the arbitrary point P on the upper surface 30.
Referring to
Sin β=n×Sin β′
α′=α+β−β′=α+β−sin−1((1/n)×sin β)
Accordingly, the condition (hereinafter, referred to as ‘condition 2’) of the upper surface 30 in consideration of the shape of the incident surface 100 may be defined as follows.
ΔR′/(R′Δα′)1/√(n2−1) Condition 2:
α′=α+β−β′=α+β−sin−1((1/n)×sin β)
(Here, α: angle between the optical axis 12 and light L that is emitted from the second reference point P2 and reaches the arbitrary point P on the incident surface 100, β: angle between the light L emitted from the second reference point P2 and a normal 14 at the arbitrary point P′ on the incident surface 100, α′: angle between the optical axis 12 and light L′ obtained via a process in which the light L reaching the arbitrary point P′ on the incident surface 100 is refracted and reaches the arbitrary point P on the upper surface 30, Δα′: increment in α′, R: distance between the arbitrary point P on the upper surface 30 and the arbitrary point P′ on the incident surface 100, ΔR′: increment in R′ with respect to Δα′, and n: refractive index of a material for forming the lens 10)
Although
Hereinafter, the LED chip 11 will be described in detail according to various embodiments of the present invention.
Referring to
In the case of the LED chip 11 with this configuration, light that is emitted directly from the light emitting portion 114 and light reflected from the reflective surface 113 are emitted from the LED chip 11 through the transparent plate 116, and thus the LED chip 11 emits light through a flat source, and in this case, the light emitting surface 112 of the LED chip 11 corresponds to an upper surface of the transparent plate 116. However, the LED chip 11 as the flat source may be configured with various shapes and embodiments of the present invention are not limited thereto.
Although the LED chip 11 emits light in the form of the flat source as described above, the LED chip 11 may be configured with a volume source. The LED chip 11 as the volume source is schematically illustrated in
As illustrated in
Referring to
A condition (hereinafter, referred to as a ‘condition 3’) of the upper surface 30.
ΔR/(RΔα)1/√(n2−1) Condition 3:
(Here, α: angle between the optical axis 12 and light that is emitted from a fourth reference point P4 and reaches the arbitrary point P when the lower end portion P4 of the side surface 118 of the LED chip 11, positioned at the same side as the arbitrary point P on the upper surface 30 based on the optical axis 12, is considered as the fourth reference point P4, Δα: increment in α, R: distance between the fourth reference point P2 and the arbitrary point P on the upper surface 30, ΔR: increment in R with respect to Δα, and n: refractive index of a material for forming the lens 10)
As described above, in this case, a condition (hereinafter, referred to as a ‘condition 4’) of the upper surface 30 in consideration of the shape of the incident surface 100 may be defined as follows.
ΔR′/(R′Δα′)1/√(n2−1) Condition 4:
α′=α+β−β′=α+β−sin−1((1/n)×sin β)
(Here, α: angle between the optical axis 12 and light L emitted from the reference point P4 and reaches an arbitrary point P′ on the incident surface 100 when the lower end portion P4 of the side surface 118 of the LED chip 11, positioned at the same side as the arbitrary point P on the upper surface 30 based on the optical axis 12, is considered as the fourth reference point P4, β: angle between the normal 14 at the arbitrary point P′ on the incident surface 100 and light L that is emitted from the fourth reference point P4 and reaches the arbitrary point P′ on the incident surface 100, α′: angle between the optical axis 12 and light L′ obtained via a process in which the light L reaching the arbitrary point P′ on the incident surface 100 is refracted and reaches the arbitrary point P on the upper surface 30, Δα′: increment in α′, R: distance between the arbitrary point P on the upper surface 30 and the arbitrary point P′ on the incident surface 100, ΔR′: increment in R′ with respect to Δα′, and n: refractive index of a material for forming the lens 10)
The side surface 40 is formed to emit light L3 as to emit light L3 incident directly on the side surface 40 among light beams, which are emitted from the LED chip 11 and incident on an inner part of the lens 10 through the incident surface 100, out of the lens 10. Like the upper surface 30, when the side-emitting LED lens 10 according to the present invention is formed such that the side surface 40 emits the light L3 incident directly thereon out of the lens 10, a light source for light emitted from the LED chip 11 may be formed to be considered as a flat source or a volume source instead of one point source, thereby minimizing the amount of light that is not emitted out of the lens 10 due to internal total-reflection on the side surface 40.
Hereinafter, the condition of the side surface 40 will be described in detail with reference to the drawings.
Referring to
The condition of the side surface 40 will now be described with reference to 1/≈(n2−1) (hereinafter, referred to as a ‘condition 5’).
That is,
ΔR/(RΔα)1/√(n2−1) condition 5:
(Here, α: angle between a horizontal axis 16 perpendicular to the optical axis 12 and light L that is emitted from the second reference point P and reaches the arbitrary point P on the side surface 40, Δα: increment in α, R: distance between the second reference point P2 and the arbitrary point P on the side surface 40, ΔR: increment in R with respect to Δα, and n: refractive index of a material for forming the lens 10)
As described above, when the side surface 40 is configured to satisfy the condition 5, almost all light beams directly incident on the side surface 40 among light beams that are emitted from the light emitting surface 112 of the LED chip 11 and incident on an inner part of the lens 10 through the incident surface 100 may be emitted out of the lens 10, thereby minimizing the amount of light that is internally total-reflected by the side surface 40.
In addition, in this case, a condition (hereinafter, referred to as a ‘condition 6’) of the side surface 40 in consideration of the shape of the incident surface 100 may be defined as follows.
ΔR′/(R′Δα′)1/√(n2−1) Condition 6:
α′=α+β−β′=α+β−sin−1((1/n)×sin β)
(Here, α: angle between the horizontal axis 16 perpendicular to the optical axis 12 and light L that is emitted from the second reference point P2 and reaches the arbitrary point P′ on the incident surface 100, β: angle between the normal 14 at the arbitrary point P′ on the incident surface 100 and the light L that is emitted from the second reference point P2 and reaches the arbitrary point P′ on the incident surface 100, α′: angle between the horizontal axis 16 perpendicular to the optical axis 12 and light L′ obtained via a process in which the light L reaching the arbitrary point P′ on the incident surface 100 is refracted and reaches the arbitrary point P on the upper surface 30, Δα′: increment in α′, R: distance between the arbitrary point P on the side surface 40 and the arbitrary point P′ on the incident surface 100, ΔR′: increment in R′ with respect to Δα′, and n: refractive index of a material for forming the lens 10)
Referring to
A condition (hereinafter, referred to as a ‘condition 7’) of the side surface 40 may be defined as follows.
ΔR/(RΔα)1/√(n2−1) Condition 7:
(Here, α: angle between the horizontal axis 16 perpendicular to the optical axis 12 and light L that is emitted from the fourth reference P4 and reaches the arbitrary point P on the side surface 40 when the lower end portion P4 of the side surface 118 of the LED chip 11, positioned at the same side as the arbitrary point P on the side surface 40 based on the optical axis 12, is determined as the fourth reference point P4, Δα: increment in α, R: distance between the fourth reference point and the arbitrary point P on the side surface 40, ΔR: increment in R with respect to Δα, and n: refractive index of a material for forming the lens 10)
As described above, when the side surface 40 is configured to satisfy the condition 7, almost all light beams directly incident on the side surface 40 among light beams that are emitted from the LED chip 11 as a volume source and incident on an inner part of the lens 10 through the incident surface 100 may be emitted out of the lens 10, thereby minimizing the amount of light that is internally total-reflected by the side surface 40.
In addition, in this case, a condition (hereinafter, referred to as a ‘condition 8’) of the side surface 40 in consideration of the shape of the incident surface 100 may be defined as follows.
ΔR′/(R′Δα′)1/√(n2−1) Condition 8:
α′=α+β−β′=α+β−sin−1((1/n)×sin β)
(Here, α: angle between the horizontal axis 16 perpendicular to the optical axis 12 and light L that is emitted from the fourth reference point P4 and reaches the arbitrary point P′ on the incident surface 100 when the lower end portion P4 of the side surface 118 of the LED chip 11, positioned at the same side as the arbitrary point P on the side surface 40 based on the optical axis 12, is determined as the fourth reference point P4, β: angle between the normal 14 at the arbitrary point P′ on the incident surface 100 and light L that is emitted from the fourth reference point P4 and reaches the arbitrary point P′ on the incident surface 100, α′: angle between the horizontal axis 16 perpendicular to the optical axis 12 and light L′ obtained via a process in which the light L reaching the arbitrary point P′ on the incident surface 100 is refracted and reaches the arbitrary point P on the side surface 40, Δα′: increment in α′, R: distance between the arbitrary point P on the side surface 40 and the arbitrary point P′ on the incident surface 100, ΔR′: increment in R′ with respect to Δα′, and n: refractive index of a material for forming the lens 10)
As described above, the present invention relates to a side-emitting LED lens for minimizing the amount of light emitted upwards through an upper surface rather than being total-reflected at the upper surface even if the upper surface is formed to total reflect light incident thereon without reflection coating when a reflective surface for emitting light emitted from an LED chip towards a side surface is formed. The embodiments of the present invention may be changed in various ways. Accordingly, the present invention is not limited to the described embodiments and any changeable forms by one of ordinary skill in the art may be within the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2013-0001019 | Jan 2013 | KR | national |
| 10-2014-0001558 | Jan 2014 | KR | national |
This application is a National Stage Application of PCT International Patent Application No. PCT/KR2014/000110 filed Jan. 6, 2014, under 35 U.S.C. §371, which claims priority to Korean Patent Application Nos. 10-2013-0001019 filed Jan. 4, 2013, and 10-2014-0001558 filed Jan. 6, 2014, which are all hereby incorporated by reference in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2014/000110 | 1/6/2014 | WO | 00 |
