Lens for wide diffusion light

Disclosed herein is a light diffusion lens. The light diffusion lens according to one embodiment of the present disclosure includes a bottom surface, an incidence surface concavely formed inward the bottom surface from one area (an incidence hole) thereof, and an exit surface from which light incident through the incidence surface is emitted, wherein at least two protrusions are formed on the incidence surface symmetrically in relation to an optical axis or at least two second dimples are formed on the exit surface symmetrically in relation to the optical axis.

CROSS-REFERENCE TO RELATED APPLICATION

Pursuant to 35 U.S.C. § 119 (a), this application claims the benefit of earlier filing dates and rights of priorities to Korean Patent Applications No. 10-2018-0138515, filed on Nov. 12, 2018, the contents of which are hereby incorporated by reference in their entirety.

BACKGROUND

Field

The present disclosure relates to a light diffusion lens.

Discussion of Related Art

Recently, the demands for flat panel display devices having more improved performance while being smaller in size and lighter in weight are explosively increasing around the rapidly developing semiconductor technology.

Among these flat panel display devices, since liquid crystal display (LCD) devices, which are recently getting attention, have advantages such as miniaturization, weight reduction, and low power consumption, and the like, the LCD devices are gradually getting attention as alternatives to overcome disadvantages of the conventional cathode ray tube (CRT). Currently, the LCD devices are installed and used in many information processing devices which need a display device.

Since LCD panels in the LCD devices are light receiving elements which do not emit light by itself, the LCD panels have backlight units for providing light to the LCD panels therebelow. Here, the backlight unit may include a lamp, a light guiding panel, a reflective sheet, an optical sheet, and the like.

The lamp employs a cold cathode fluorescent lamp generating relatively low heat, generating white light near natural light, and having a long service life, or a light emitting diode (LED) type lamp having excellent color reproducibility and low power consumption. The cold cathode fluorescent lamp was conventionally used. However, since the LED type lamp has advantages of excellent color reproducibility and low power consumption, products of LED type lamps have begun to be employed.

The disclosure of this section is to provide background information relating to the invention. Applicant does not admit that any information contained in this section constitutes prior art.

SUMMARY

The present disclosure is directed to a light diffusion lens which minimizes a dark portion formed in light diffused through a lens using a dimple formed on an incidence surface or an exit surface.

The present disclosure is also directed to a light diffusion lens which is capable of securing light diffusivity and light uniformity by changing an optical path of a part of light having directivity in a specific direction using a dimple formed on an incidence surface or an exit surface.

The present disclosure is also directed to a light diffusion lens which is capable of preventing or minimizing a dark portion, which may be formed in diffused light, by proposing a shape or a position of a dimple formed on an incidence surface, a shape or a position of a dimple formed on an exit surface, and a relationship between the dimple formed on the incidence surface and the dimple formed on the exit surface in terms of design.

In one general aspect, there may be provided a light diffusion lens comprising: a bottom surface; an incidence surface concavely formed inward the bottom surface from one area (an incidence hole) thereof; and an exit surface from which light incident through the incidence surface is emitted, wherein at least two protrusions are formed on the incidence surface symmetrically in relation to an optical axis.

In some exemplary embodiment of the present invention, each of the at least two protrusions may be disposed within a predetermined divergence angle based on the optical axis, and the divergence angle is less than or equal to 50 degrees.

In some embodiment of the present invention, each of the at least two protrusions may be convexly formed from the incidence surface toward the optical axis.

In some embodiment of the present invention, an edge at which the at least two protrusions and the incidence surface meet may have a circular shape.

In some embodiment of the present invention, the sum of areas of the at least two protrusions may be less than or equal to 30% of an entire area of the incidence surface.

In some embodiment of the present invention, any point on each of the at least two protrusions may correspond to the center of the height of the incidence surface.

In some embodiment of the present invention, at least two dimples may be formed on the exit surface symmetrically in relation to the optical axis.

In some embodiment of the present invention, each of the at least two dimples may be disposed within a predetermined divergence angle based on the optical axis, and an angle between the optical axis and a center of each of the at least two dimples may range from about 36 degrees to about 40 degrees.

In some embodiment of the present invention, each of the at least two dimples may have an elliptical shape.

In other general aspect of the present invention, there may be provided a light diffusion lens comprising: a bottom surface having an elliptical shape; an incidence surface concavely formed inward the bottom surface from one area (an incidence hole) thereof; and an exit surface from which light incident through the incidence surface is emitted, wherein at least two dimples are disposed on the exit surface symmetrically in relation to an optical axis.

In some embodiment of the present invention, each of the at least two dimples may be disposed within a predetermined divergence angle based on the optical axis, and an angle between the optical axis and a center of each of the at least two dimples may range from about 36 degrees to about 40 degrees.

In some embodiment of the present invention, each of the at least two dimples may have an elliptical shape.

In another general aspect of the present invention, there may be provided a light diffusion lens comprising: a bottom surface having an elliptical shape; an incidence surface concavely formed inward the bottom surface from one area (an incidence hole) thereof; and an exit surface from which light incident through the incidence surface is emitted, wherein a first dimple of an elliptical shape is formed on the exit surface at a position of a predetermined first radius from an optical axis, at least two second dimples having an elliptical shape are formed on the exit surface at a position of a second radius that is smaller than the first radius, and a third dimple having an elliptical shape is formed on the exit surface at a position of a third radius that is smaller than the second radius.

In some embodiment of the present invention, a long axis of the bottom surface may be disposed to correspond to short axes of the first and third dimples.

In some embodiment of the present invention, length of long axis of each of the at least two second dimples may be smaller than that of long axis of the first dimple and may be greater than that of long axis of the third dimple.

DETAILED DESCRIPTION OF EMBODIMENTS

The present disclosure may be applied with various changes, and may be included with various embodiments, and particular embodiments will be exemplified by drawings and explained in the Detailed Description. However, the present disclosure will not be limited to the particular embodiments, and the described aspect is intended to embrace all such alterations, modifications, and variations that fall within the scope and novel idea of the present disclosure.

Accordingly, in some embodiments, well-known processes, well-known device structures, and well-known techniques are not illustrated in detail to avoid unclear interpretation of the present disclosure.

Light emitted from an LED may have strong directivity and tends to concentrate in a front direction of the LED. Therefore, in some instances light is not uniformly distributed throughout the LCD panel and a front portion of the LED becomes brighter and a portion away from the front portion thereof becomes darker. Thus, the demands for technology to effectively and uniformly diffuse the light of LED are increasing.

In particular, in real life, a size of the LCD panel is increased due to high brightness and high efficiency of the LED, and the LED emits light through four or five surface-emission instead of one surface-emission so that the demands for technology to effectively and uniformly diffuse the light of the LED are increasing.

Therefore, the demands are also increasing for lens technology for designing an incidence surface on which light is incident and an exit surface from which the light is emitted so as to allow the LED to implement surface emission and, on the basis of the design, minimizing a dark portion which is locally generated due to a lens such that uniformity of the light can be improved.

First Embodiment

FIG. 1is a perspective view illustrating a light diffusion lens according to a first embodiment,FIG. 2is a bottom view illustrating the light diffusion lens according to the first embodiment,FIG. 3is a plan view illustrating the light diffusion lens according to the first embodiment,FIG. 4is a side view illustrating the light diffusion lens according to the first embodiment,FIG. 5is a cross-sectional view illustrating the light diffusion lens according to the first embodiment,FIG. 6is an enlarged view illustrating area A ofFIG. 5, andFIG. 7is a diagram illustrating an arrangement relationship between a light source and the light diffusion lens according to the first embodiment. Here,FIG. 5is a cross-sectional view taken along line A1-A1ofFIG. 1. InFIGS. 4 and 5, an R direction indicates a radial direction, and a Z direction indicates an axial direction or an optical axis direction.

Meanwhile, an optical axis C may be a center of light emitted from a light source10and may coincide with a center of a light diffusion lens1.

The light diffusion lens1according to the first embodiment may be used in a liquid crystal display device. In this case, the liquid crystal display device may include a substrate and a plurality of light sources10which are mounted on the substrate. The light diffusion lens1may be disposed to cover the light source10to diffuse the light emitted from the light source10. In this case, the light diffusion lens1may diffuse the light using a protrusion or bulge formed on an aspherical-shaped incidence surface200, thereby improving light uniformity.

Referring toFIGS. 1 to 7, the light diffusion lens1according to the first embodiment may include a bottom surface100, the incidence surface200on which light is incident, an exit surface300from which the light incident through the incidence surface200is emitted, and first protrusions or bulges400convexly formed on the incidence surface200. Here, the exit surface300may include a top surface310and a side surface320. In this case, the top surface310may be convexly formed toward an upper side. Here, the “upper side” and a “lower side” are relative expressions. Unless otherwise defined below, a direction from the bottom surface100to the top surface310is determined as the upper side (upward side), and, conversely, a direction from the top surface310to the bottom surface100is determined as the lower side (downward side).

Therefore, the light diffusion lens1may diffuse the light emitted from the light source10using the aspherical-shaped incidence surface200, the exit surface300, and the first protrusions400formed on the incidence surface200.

In embodiments, in the light diffusion lens1, since an optical path of the light emitted from the light source10is changed due to shapes of the incidence surface200and the exit surface300and the first protrusions400, the incidence surface200which is formed in the aspherical shape, the shape of the exit surface300, and arrangements, shapes, and sizes of the first protrusions400act as largest factors of light distribution according to the change of the optical path of the light.

The light diffusion lens1may be formed using a material of polycarbonate or polymethmethylacrylate. Here, a refractive index of polycarbonate is 1.58, and a refractive index of polymethmethylacrylate is 1.49.

Referring toFIG. 3, the bottom surface100may be formed in a circular shape in which an incidence hole210is disposed at a center thereof.

Further, the bottom surface100may be formed in a downwardly convex shape or a flat surface shape.

The downwardly convex-shaped bottom surface100may be a curved surface having a curvature that is greater than that of a central portion of the top surface310.

An example of the bottom surface100includes a bottom surface formed of a curved surface having a downwardly convex shape, but the present disclosure is not necessarily limited thereto. For example, in the bottom surface100, a flat surface may be formed from an edge to a predetermined length in a center direction, and a lower convex surface may be formed from a position at which the flat surface ends to a center side. In embodiments, the bottom surface100may have a shape of which curvature is zero from the edge to a predetermined length in the center direction and increases and then decreases again to the center of the bottom surface100from the predetermined length.

When compared with a bottom surface comprised of only the flat surface, the bottom surface100having the lower convex surface may totally reflect more light, which is emitted to the lower side, toward the upper side among lights emitted from the light source10.

Here, in order to preferentially totally reflect the light due to the lower convex surface, the flat surface may be disposed outside the lower convex surface.

Further, the bottom surface100of a flat surface shape may be formed to be inclined from an end portion of a lower side of the side surface320toward the optical axis C. Referring toFIG. 4, the bottom surface100of a flat surface shape may be a flat surface which is formed to be inclined with respect to an imaginary horizontal surface at a predetermined angle based on the end portion of the lower side of the side surface320. Accordingly, the bottom surface100may totally reflect more light, which is emitted to the lower side, toward the upper side among lights emitted from the light source10.

The incidence surface200is a surface portion through which the light emitted from the light source10located in the incidence hole210is incident into the light diffusion lens1.

As shown inFIGS. 1 and 5, the aspherical-shaped incidence surface200may be formed to be concave inward the bottom surface100from the center thereof. Accordingly, the incidence hole210may be formed in the center of the bottom surface100.

A vertical cross section of the incidence surface200may be formed in a semi-elliptical shape, a semi-rugby ball shape, or a parabolic shape. Accordingly, the incidence surface200may be formed of an aspherical surface. In this case, the incidence surface200may be formed to have a predetermined height H1from the bottom surface100based on the optical axis direction.

Referring toFIGS. 1,3, and 5, a horizontal cross section of the incidence surface200may have a circular shape which is formed to have a predetermined radius. In this case, since the vertical cross section of the incidence surface200is formed in a semi-elliptical shape, a semi-rugby ball shape, or a parabolic shape, a radius of the horizontal cross section of the incidence surface200may be decreased toward the upper side. Accordingly, the incidence surface200may have a maximum radius R1.

The incidence hole210may be formed in a circular shape which is formed with a predetermined radius. In this case, since the incidence hole210is disposed below the incidence surface200, the incidence surface200may be formed with the maximum radius R1in the incidence hole210. Here, the maximum radius R1of the incidence surface200may be called a first radius.

A center of the incidence hole210may be disposed on the optical axis C, and the light source10may be disposed at the center of the incidence hole210. Accordingly, an air layer may be disposed between the light source10and the incidence surface200. Thus, light emitted from the light source10to the air layer may be refracted at the incidence surface200of the light diffusion lens1having a different refractive index.

The exit surface300may be a surface of the light diffusion lens1from which the light incident through the incidence surface200is emitted and may be formed to be rotationally symmetrical based on the optical axis C. Accordingly, as shown inFIG. 3, when the exit surface300is viewed from the optical axis direction, the exit surface300may be formed in a circular shape so as to have a predetermined radius R2. Here, the radius R2of the exit surface300may be called a second radius.

A height H2of the exit surface300may be smaller than the radius R2of the exit surface300.

Referring toFIG. 4, the exit surface300may include the convex-shaped top surface310and the side surface320disposed between the top surface310and the bottom surface100. In this case, the side surface320may be disposed parallel to the optical axis C. Further, some of lights incident into the light diffusion lens1through the incidence surface200is refracted through the top surface310to be emitted to the outside.

The top surface310may be convexly formed in a hemispherical shape or a rotationally symmetrical shape. For example, the top surface310may be convexly formed in the optical axis direction (the Z direction).

In this case, the top surface310may be symmetrically formed based on an imaginary vertical flat surface passing through the optical axis C. Accordingly, the top surface310may implement a symmetrical optical path based on the optical axis C.

The top surface310may be formed in a convex shape of which curvature is gradually increased from a central portion of an uppermost end of the top surface310toward an edge portion thereof. Alternatively, the central portion of the uppermost end of the top surface310may be flatter than the edge portion thereof.

The first protrusion400may be convexly formed toward the optical axis C. Accordingly, the first protrusion400may be called a first protruding portion or a first protrusion.

A plurality of first protrusions400may be formed on the incidence surface200, and the sum of the plurality of first protrusions400may be 30% or less of an entire area of the incidence surface200.

In embodiments, the plurality of first protrusions400are formed to have an area of 30% or less of the entire area of the incidence surface200. When the first protrusions400have an area exceeding 30% of the entire area of the incidence surface200, the first protrusions400affect overall image quality of the light diffusion lens1. For example, since paths of reflected light and returned light are changed when the entire area of the plurality of first protrusions400increases, when the plurality of first protrusions400are applied, the sum of the entire area of the plurality of first protrusions400are less than or equal to 30% of the entire area of the incidence surface200.

Referring toFIG. 7, since some of the lights emitted from the light source10may be emitted at a predetermined divergence angle θ based on the optical axis C, the first protrusion400is disposed within the divergence angle θ so that the light is refracted to the top surface310of the exit surface300and then emitted. Accordingly, the light diffusion lens1may secure light diffusivity and light uniformity by changing the optical path of some of the lights, which have directivity in a specific direction, through the first protrusion400. In this case, the divergence angle θ may be 50 degrees or less based on the optical axis C. In embodiments, the first protrusion400is disposed within 50 degrees based on the optical axis C.

Referring toFIGS. 5 and 6, the first protrusion400may be formed of a first curved surface410having a predetermined curvature in a vertical cross section. Thus, the first curved surface410may convexly be formed on the incidence surface200toward the optical axis C.

A center C1of the first curved surface410may be disposed in the light diffusion lens1. In this case, the center C1of the first curved surface410may be disposed on an imaginary line L passing through a center C2of the height H1of the incidence surface200in a horizontal direction based on the optical axis direction. In this case, the line L may be disposed above the side surface320.

Referring toFIG. 5, two first protrusions400may be symmetrically disposed based on the optical axis C in the vertical cross section. Accordingly, the light diffusion lens1may improve light uniformity in the radial direction. Here, in consideration of the light emitted from the light source10, two or more or three or more first protrusions400may be disposed. Additionally, in consideration of light uniformity in the radial direction, two or more even numbers of first protrusions400may be symmetrically disposed based on the optical axis C.

Alternatively, the first protrusion400may be formed in a hemispherical shape to protrude from the incidence surface200. Here, a cross section of the first protrusion400may be formed in a circular shape.

Referring toFIG. 1, an edge at which the first protrusion400and the incidence surface200meet may be formed in a circular shape. Here, the edge at which the first protrusion400and the incidence surface200meet may be called a first edge.

Accordingly, as shown inFIG. 5, the edge may be formed to have a predetermined diameter D1. Further, the diameter D1may be formed to be smaller than the first radius R1which is the maximum radius from the optical axis C to the incidence surface200.

The edge may include one point P1at a lower end and one point P2at an upper end based on the optical axis direction. Here, the one point P1at the lower end may be called a first point, and the one point P2at the upper end may be called a second point.

Referring toFIG. 6, in embodiments, the first protrusion400is disposed within a predetermined available range based on the radial direction. Here, the available range may indicate a range between a distance R3from the optical axis C to the one point P1at the lower end of the edge in the radial direction and a distance R4from the optical axis C to the one point P2at the upper end of the edge in the radial direction. In one embodiment, the available range may be a factor which indicates how far the first protrusion400is away from the optical axis C in the radial direction.

Therefore, when the first protrusion400is disposed outside the available range, a dark portion and a bright portion are generated in an image due to internal reflection of the light diffusion lens1such that light uniformity may be degraded. Here, the dark portion may mean an area that is darker than a periphery of light formed using a light diffusion lens. Further, the bright portion may mean an area that is brighter than the periphery of the light formed using the light diffusion lens.

Consequently, the light diffusion lens1may secure the light uniformity by locating the first protrusion400within the available range.

As shown inFIG. 5, the distance R3from the optical axis C to the one point P1at the lower end of the edge may be formed to be greater than the distance R4from the optical axis C to the one point P2at the upper end of the edge. The distance R3from the optical axis C to the one point P1at the lower end of the edge may be formed to be smaller than the first radius R1which is the maximum radius.

Therefore, the light diffusion lens1may define the distance R3from the optical axis C to the one point P1at the lower end of the edge and the distance R4from the optical axis C to the one point P2at the upper end of the edge based on the first radius R1, thereby presenting an arrangement position of the first protrusion400.

Here, the first radius R1may be 6.1 to 6.2 times a difference R3-R4between the distance R3from the optical axis C to the one point P1at the lower end of the edge and the distance R4from the optical axis C to the one point P2at the upper end of the edge. Specifically, the first radius R1may be 6.12 times the difference R3-R4between the distance R3from the optical axis C to the one point P1at the lower end of the edge and the distance R4from the optical axis C to the one point P2at the upper end of the edge.

Further, the diameter D1of the edge may be formed to be greater than the difference R3-R4between the distance R3from the optical axis C to the one point P1at the lower end of the edge and the distance R4from the optical axis C to the one point P2at the upper end of the edge.

Therefore, the light diffusion lens1may define the distance R3from the optical axis C to the one point P1at the lower end of the edge and the distance R4from the optical axis C to the one point P2at the upper end of the edge based on the diameter D1of the edge, thereby presenting a size of the first protrusion400.

Here, the diameter D1of the edge may be 3.3 to 3.4 times the difference R3-R4between the distance R3from the optical axis C to the one point P1at the lower end of the edge and the distance R4from the optical axis C to the one point P2at the upper end of the edge. Specifically, the diameter D1of the edge may be 3.37 times the difference R3-R4between the distance R3from the optical axis C to the one point P1at the lower end of the edge and the distance R4from the optical axis C to the one point P2at the upper end of the edge.

FIG. 8is a diagram illustrating an optical path due to a first protrusion of the light diffusion lens according to the first embodiment, andFIG. 9shows photographs illustrating before and after application of the first protrusion. Here,FIG. 9Ais a photograph illustrating light formed by a light diffusion lens in which a first protrusion is omitted from the light diffusion lens according to the first embodiment, andFIG. 9Bis a photograph illustrating light formed by the light diffusion lens, to which the first protrusion is applied, according to the first embodiment.

Referring toFIG. 8, lights incident into the first protrusion400may be refracted by the first protrusion400to improve light uniformity of the light diffusion lens1. For example, the lights incident into the first protrusion400may be collected by the first protrusion400and refracted to the top surface310. For example, the first protrusion400may serve as a converging lens.

Thus, as shown inFIG. 9A, when the first protrusion is omitted from the light diffusion lens according to the first embodiment, a dark portion is formed. However, as shown inFIG. 9B, when the first protrusion400is applied to the light diffusion lens1according to the first embodiment, it can be confirmed that a dark portion is removed such that light uniformity is improved.

In this case, a five surface emission light-emitting diode (LED) may be used as the light source10. Accordingly, the first protrusion400is disposed in the same radial direction to correspond to a side light-emitting surface12such that the light uniformity may be improved.

FIG. 10is a diagram illustrating a light source for emitting light to an incidence surface of the light diffusion lens according to the first embodiment.

Referring toFIG. 10, the light source10emitting light toward the incidence surface200may include a top light-emitting surface11and four side light-emitting surfaces12. Thus, the light source10may implement five surface emission. In this case, a bottom surface of the light source10may be disposed to be in contact with a top surface of a substrate20. Here, an example in which the five surface emission LED is used as the light source10has been described, but the present disclosure is not necessarily limited thereto.

Light emitted from the top light-emitting surface11of the light source10may be emitted in the optical axis direction, and light emitted from the side light-emitting surface12may be emitted in the radial direction of the light diffusion lens1. Further, an optical axis apex11amay be formed at a center of the top light-emitting surface11. In this case, the optical axis apex11amay be disposed on a line of the optical axis C.

Further, the first protrusion400of the light diffusion lens1may be disposed in the same radial direction as the side light-emitting surface12to correspond to the side light-emitting surface12.

Meanwhile, a yellow fluorescent material may be applied to the light source10.

Second Embodiment

FIG. 11is a perspective view illustrating a light diffusion lens according to a second embodiment,FIG. 12is a bottom view illustrating the light diffusion lens according to the second embodiment,FIG. 13is a plan view illustrating the light diffusion lens according to the second embodiment,FIG. 14is a side view illustrating the light diffusion lens according to the second embodiment,FIG. 15is a cross-sectional view illustrating the light diffusion lens according to the second embodiment,FIG. 16is an enlarged view illustrating area B ofFIG. 15, andFIG. 17is a diagram illustrating an arrangement relationship between a light source and the light diffusion lens according to the second embodiment. Here,FIG. 15is a cross-sectional view taken along line A2-A2ofFIG. 11.

In describing a light diffusion lens1aaccording to the second embodiment, the same components as those of the light diffusion lens1according to the first embodiment are denoted by the same reference numerals, and thus detailed descriptions thereof will be omitted herein.

Comparing the light diffusion lens1aaccording to the second embodiment with the light diffusion lens1according to the first embodiment, the light diffusion lens1aaccording to the second embodiment is different from the light diffusion lens1in that the first protrusions400are omitted and second dimples500are included.

Referring toFIGS. 11 to 17, the light diffusion lens1aaccording to the second embodiment may include a bottom surface100, an incidence surface200into which light is incident, an exit surface300from which the light incident through the incidence surface200is emitted, and second dimples500concavely formed on the exit surface300. Here, the exit surface300may include a top surface310and a side surface320.

Therefore, the light diffusion lens1amay diffuse light emitted from a light source10using the aspherical-shaped incidence surface200, the exit surface300, and the second dimples500formed on the exit surface300.

In embodiments, in the light diffusion lens1a, since an optical path of the light emitted from the light source10is changed due to shapes of the incidence surface200and the exit surface300and the second dimples500, the incidence surface200which is formed in the aspherical shape, the shape of the exit surface300, and arrangements, shapes, and sizes of the second dimples500act as largest factors of light distribution according to the change of the optical path of the light.

The second dimple500may be concavely formed on the top surface310of the exit surface300toward an optical axis C. Accordingly, the second dimple500may be called a first concave portion or a first groove.

Referring toFIG. 17, since some of the lights emitted from the light source10may be emitted at a predetermined divergence angle θ based on the optical axis C, the second dimple500is disposed within the divergence angle θ so that the light is refracted to be emitted. Accordingly, the light diffusion lens1amay secure light diffusivity and light uniformity by changing the optical path of some of the lights, which have directivity in a specific direction, through the second dimple500. In this case, the divergence angle θ may be 50 degrees or less based on the optical axis C. Specifically, a center C3at which a long axis520and a short axis530of the second dimple500meet may be disposed within 34 to 40 degrees based on the optical axis C. Preferably, the center C3of the second dimple500may be disposed at an angle of 37 degrees based on the optical axis C.

Referring toFIG. 15, the second dimple500may include a second curved surface510which is formed of a curved surface in a vertical cross section. Thus, the second curved surface510may be concavely formed on the exit surface300toward the optical axis C. In this case, a cross section of the second dimple500may be formed in an elliptical shape including a long axis and a short axis.

Referring toFIG. 15, two second dimples500may be symmetrically disposed based on the optical axis C in the vertical cross section. Accordingly, the light diffusion lens1amay improve light uniformity in the radial direction. Here, in consideration of the light emitted from the light source10, two or more or three or more second dimples500may be disposed. Additionally, in consideration of light uniformity in the radial direction, two or more even numbers of second dimples500may be disposed to face each other based on the optical axis C.

Referring toFIGS. 11 and 13, an edge at which the second dimple500and the exit surface300meet may be formed in an elliptical shape. Here, the edge at which the second dimple500and the exit surface300meet may be called a second edge.

Accordingly, as shown inFIG. 13, the edge may be formed in an elliptical shape including the long axis520and the short axis530.

Referring toFIG. 16, the edge at which the second dimple500and the exit surface300meet may include one point P3at a lower end and one point P4at an upper end based on the optical axis direction. Here, the one point P3at the lower end may be called a third point, and the one point P4at the upper end may be called a fourth point.

Referring toFIG. 16, in embodiments, the second dimple500is disposed within a predetermined available range based on the radial direction. Here, the available range may indicate a range between a distance R5from the optical axis C to the one point P3at the lower end of the edge in the radial direction and a distance R6from the optical axis C to the one point P4at the upper end of the edge in the radial direction.

Therefore, when the second dimple500is disposed outside the available range, a dark portion and a bright portion are generated in an image due to external refraction of the light diffusion lens1asuch that light uniformity may be degraded.

Consequently, the light diffusion lens1amay secure the light uniformity by locating the second dimple500within the available range.

As shown inFIG. 15, the distance R5from the optical axis C to the one point P3at the lower end of the edge may be formed to be greater than the distance R6from the optical axis C to the one point P4at the upper end of the edge. Further, the distance R6from the optical axis C to the one point P4at the upper end of the edge may be formed to be greater than the first radius R1which is the maximum radius.

Therefore, the light diffusion lens1amay define the distance R5from the optical axis C to the one point P3at the lower end of the edge and the distance R6from the optical axis C to the one point P4at the upper end of the edge based on the first radius R1, thereby presenting an arrangement position of the second dimple500.

Here, the first radius R1may be 4.4 to 4.5 times a difference R5-R6between the distance R5from the optical axis C to the one point P3at the lower end of the edge and the distance R6from the optical axis C to the one point P4at the upper end of the edge. Specifically, the first radius R1may be 4.47 times the difference R5-R6between the distance R5from the optical axis C to the one point P3at the lower end of the edge and the distance R6from the optical axis C to the one point P4at the upper end of the edge.

Further, a size of the second dimple500may be presented according to a ratio between the long axis520and the short axis530of the edge. In this case, a length L1of the long axis520is greater than a length L2of the short axis530. Consequently, the light diffusion lens1amay increase a diffusion amount of light in a long axis direction of the second dimple500.

Here, the length L1of the long axis520may be 5.5 to 6.5 times the length L2of the short axis530. Specifically, the length L1of the long axis520may be six times the length L2of the short axis530.

Further, a radius R2of the exit surface300may be 3.5 times the length L1of the long axis520.

FIG. 18is a diagram illustrating an optical path due to a second dimple of the light diffusion lens according to the second embodiment, andFIG. 19shows photographs illustrating before and after application of the second dimple. Here,FIG. 19Ais a diagram illustrating light formed by a light diffusion lens in which a second dimple is omitted from the light diffusion lens according to the second embodiment, andFIG. 19Bis a diagram illustrating light formed by the light diffusion lens, to which the second dimple is applied, according to the second embodiment.

Referring toFIG. 18, lights incident into the second dimple500may be refracted by the second dimple500to improve light uniformity of the light diffusion lens1a. For example, the lights incident into the second dimple500may diverge by the second dimple500to be emitted to the outside. For example, the second dimple500may serve as a diverging lens.

Thus, as shown inFIG. 19A, when the second dimple is omitted from the light diffusion lens according to the second embodiment, a dark portion is formed. However, as shown inFIG. 19B, when the second dimple500is applied to the light diffusion lens1aaccording to the second embodiment, it can be confirmed that a dark portion and a bright portion are improved such that light uniformity is improved.

In this case, a five surface emission LED may be used as the light source10. Accordingly, the second dimple500is disposed in the same radial direction to correspond to a side light-emitting surface12such that the light uniformity of the light diffusion lens1amay be improved.

Third Embodiment

FIG. 20is a perspective view illustrating a light diffusion lens according to a third embodiment,FIG. 21is a bottom view illustrating the light diffusion lens according to the third embodiment,FIG. 22is a plan view illustrating the light diffusion lens according to the third embodiment,FIG. 23is a side view illustrating the light diffusion lens according to the third embodiment,FIG. 24is a cross-sectional view illustrating the light diffusion lens according to the third embodiment,FIG. 25is an enlarged view illustrating area D ofFIG. 24, andFIG. 26is a diagram illustrating an arrangement relationship between a light source and the light diffusion lens according to the third embodiment. Here,FIG. 24is a cross-sectional view taken along line A3-A3ofFIG. 20.

In describing a light diffusion lens1baccording to the third embodiment, the same components as those of the light diffusion lens1according to the first embodiment and the light diffusion lens1aaccording to the second embodiment are denoted by the same reference numerals, and thus detailed descriptions thereof will be omitted herein.

Comparing the light diffusion lens1baccording to the third embodiment with the light diffusion lens1according to the first embodiment, the light diffusion lens1baccording to the third embodiment is different from the light diffusion lens1in that second dimples500are further included.

Referring toFIGS. 20 to 26, the light diffusion lens1baccording to the third embodiment may include a bottom surface100, an incidence surface200into which light is incident, an exit surface300from which the light incident through the incidence surface200is emitted, first protrusions400convexly formed on the incidence surface200, and second dimples500concavely formed on the exit surface300. Here, the exit surface300may include a top surface310and a side surface320.

Therefore, the light diffusion lens1bmay diffuse light emitted from a light source10using the aspherical-shaped incidence surface200, the exit surface300, the first protrusions400formed on the incidence surface200, and the second dimples500formed on the exit surface300.

In embodiments, in the light diffusion lens1b, since an optical path of the light emitted from the light source10is changed due to shapes of the incidence surface200and the exit surface300, the first protrusions400, and the second dimples500, the incidence surface200which is formed in the aspherical shape, the shape of the exit surface300, and arrangements, shapes, and sizes of the second dimples500act as largest factors of light distribution according to the change of the optical path of the light. In this case, the second dimple500may be formed to correspond to light refracted due to the first protrusion400.

The second dimple500may be concavely formed on the top surface310of the exit surface300toward an optical axis C. Accordingly, the second dimple500may be called a concave portion.

Referring toFIG. 26, since some of the lights emitted from the light source10may be emitted at a predetermined divergence angle θ based on the optical axis C, the first protrusion400and the second dimple500are disposed within the divergence angle θ so that the light is refracted to be emitted. Accordingly, the light diffusion lens1bmay secure light diffusivity and light uniformity by changing the optical path of some of the lights, which have directivity in a specific direction, through the first protrusion400and the second dimple500. In this case, the divergence angle θ may be 50 degrees or less based on the optical axis C.

In this case, a divergence angle applied to arrange the second dimple500based on the optical axis C may be smaller than a divergence angle for application of the first protrusion400. In one embodiment, as shown inFIG. 26, the second dimple500may be disposed close to the optical axis C based on the divergence angle for application of the first protrusion400.

Referring toFIG. 24, two first protrusions400and two second dimples500may be symmetrically disposed based on the optical axis C in a vertical cross section. Accordingly, the light diffusion lens1bmay improve light uniformity in the radial direction. Here, in consideration of the light emitted from the light source10, two or more first protrusions400and two or more second dimples500may be disposed. Additionally, in consideration of optical uniformity in the radial direction, two or more even numbers of first protrusions400and two or more even numbers of second dimples500may be disposed to face each other based on the optical axis C.

In this case, as shown inFIGS. 20 and 24, the first protrusion400and the second dimple500may be disposed in the same radial direction.

Meanwhile, an edge at which the first protrusion400and the incidence surface200meet may be formed in a circular shape having a predetermined diameter D1. Further, an edge at which the second dimple500and the exit surface300meet may be formed in an elliptical shape including a long axis520and a short axis530. In this case, the diameter D1of the edge at which the first protrusion400and the incidence surface200meet may be smaller than a length L1of the long axis520of the edge at which the second dimple500and the exit surface300meet. In this case, the diameter D1of the edge at which the first protrusion400and the incidence surface200meet may be greater than a length L2of the short axis530of the edge at which the second dimple500and the exit surface300meet.

FIG. 27is a diagram illustrating an optical path due to a second dimple of the light diffusion lens according to the second embodiment.

Referring toFIG. 27, lights incident into the first protrusion400may be collected by the first protrusion400and incident into the second dimple500. Further, the lights incident into the second dimple500may be diffused by the second dimple500and emitted to the outside.

Consequently, the light diffusion lens1bmay further improve light uniformity by applying the second dimple500to an area of a minute dark portion or a minute bright portion which is not resolved through the application of the first protrusion400.

Meanwhile, a five surface emission LED may be used as the light source10. Accordingly, a plurality of the first protrusions400and a plurality of the second dimples500are disposed in the same radial direction to correspond to a side light-emitting surface12such that the light uniformity of the light diffusion lens1bmay be improved.

Fourth Embodiment

FIG. 28is a perspective view illustrating a light diffusion lens according to a fourth embodiment,FIG. 29is a bottom view illustrating the light diffusion lens according to the fourth embodiment,FIG. 30is a plan view illustrating the light diffusion lens according to the fourth embodiment,FIG. 31is a front view illustrating the light diffusion lens according to the fourth embodiment,FIG. 32is a side view illustrating the light diffusion lens according to the fourth embodiment,FIG. 33is a cross-sectional view in a long axis direction based on an exit surface of the light diffusion lens according to the fourth embodiment,FIG. 34is a cross-sectional view in a short axis direction based on the exit surface of the light diffusion lens according to the fourth embodiment, andFIG. 35is an enlarged view illustrating area E ofFIG. 33. Here,FIG. 33is a cross-sectional view taken along line A4-A4ofFIG. 28, andFIG. 34is a cross-sectional view taken along line A5-A5ofFIG. 28. InFIG. 28, an x direction indicates a long axis direction based on an exit surface, a y direction indicates a short axis direction based on the exit surface, and a z direction indicates an axial direction or an optical axis direction.

Meanwhile, an optical axis C may be a center of light emitted from a light source10and may coincide with a center of a light diffusion lens1c.

Comparing the light diffusion lens1caccording to the fourth embodiment with the light diffusion lens1according to the first embodiment, the light diffusion lens1caccording to the fourth embodiment is different from the light diffusion lens1in that each of a bottom surface100a, an incidence hole210a, an exit surface300a, and third protrusions600is formed to have a long axis and a short axis.

Referring toFIGS. 28 to 33, the light diffusion lens1caccording to the fourth embodiment may include the bottom surface100a, an incidence surface200aconcavely formed inward the bottom surface100ato form the incidence hole210a, the exit surface300afrom which light incident through the incidence surface200ais emitted, and the third protrusions600convexly formed on the incidence surface200a. Here, the exit surface300amay be formed to have a first long axis330with a predetermined first long axis length Dx1and a first short axis340with a predetermined first short axis length Dy1. Thus, the incidence surface200amay also be formed to have the first long axis length Dx1and the first short axis length Dy1. Further, the exit surface300amay include a top surface310aand a side surface320a.

Therefore, the light diffusion lens1cmay diffuse the light emitted from the light source10using the aspherical-shaped incidence surface200a, the exit surface300a, and the third protrusions600formed on the incidence surface200a.

In embodiments, in the light diffusion lens1c, since an optical path of the light emitted from the light source10is changed due to shapes of the incidence surface200aand the exit surface300aand the third protrusions600, the shapes and arrangement of the incidence surface200a, which is formed in the aspherical shape, and the exit surface300a, and arrangements, shapes, and sizes of the third protrusions600act as largest factors of light distribution according to the change of the optical path of the light.

Referring toFIG. 29, the incidence hole210amay be disposed at a center of the bottom surface100a. Further, since the bottom surface100ais disposed below the exit surface300a, the bottom surface100amay be formed to have the first long axis length Dx1and the first short axis length Dy1. Accordingly, the bottom surface100amay be formed in an elliptical shape.

Further, the bottom surface100amay be formed in a downwardly convex shape or a flat surface shape.

The downwardly convex-shaped bottom surface100amay be a curved surface having a curvature that is greater than that of a central portion of the top surface310a.

An example of the bottom surface100aincludes a bottom surface formed of a curved surface having a downwardly convex shape, but the present disclosure is not necessarily limited thereto. For example, in the bottom surface100a, a flat surface may be formed from an edge to a predetermined length in a center direction, and a lower convex surface may be formed from a position at which the flat surface ends to a center side. In embodiments, the bottom surface100amay have a shape of which curvature is zero from the edge to a predetermined length in the center direction and increases and then decreases again to the center of the bottom surface100afrom the predetermined length.

When compared with a bottom surface comprised of only the flat surface, the bottom surface100ahaving the lower convex surface may totally reflect more light, which is emitted to the lower side, toward the upper side among lights emitted from the light source10.

Here, in order to preferentially totally reflect the light due to the lower convex surface, the flat surface may be disposed outside the lower convex surface.

Further, the bottom surface100aof a flat surface shape may be formed to be inclined from an end portion of a lower side of the side surface320atoward the optical axis C. For example, the bottom surface100aof a flat surface shape may be a flat surface which is formed to be inclined with respect to an imaginary horizontal surface at a predetermined angle based on the end portion of the lower side of the side surface320a. Accordingly, the bottom surface100amay totally reflect more light, which is emitted to the lower side, toward the upper side among lights emitted from the light source10.

The incidence surface200ais a surface portion through which the light emitted from the light source10located in the incidence hole210ais incident into the light diffusion lens1c.

As shown inFIGS. 28, 33, and 34, the aspherical-shaped incidence surface200amay be formed to be concave inward the bottom surface100afrom the center thereof. Accordingly, the incidence hole210amay be formed at the center of the bottom surface100a.

A vertical cross section of the incidence surface200amay be formed in a semi-elliptical shape, a semi-rugby ball shape, or a parabolic shape. Accordingly, the incidence surface200amay be formed of an aspherical surface. In this case, the incidence surface200amay be formed to have a predetermined height H1from the bottom surface100abased on the optical axis direction.

Referring toFIGS. 28 and 29, since the incidence surface200aextends upward from the incidence hole210a, a horizontal cross section of the incidence surface200amay have an elliptical shape. In this case, since the vertical cross section of the incidence surface200ais formed in a semi-elliptical shape, a semi-rugby ball shape, or a parabolic shape, the horizontal cross section of the incidence surface200amay be decreased toward the upper side.

The incidence hole210amay include a second long axis211formed with a second long axis length Dy2and a second short axis212formed with a second short axis length Dx2. Here, when the exit surface300ais viewed in the optical axis direction, the second short axis212of the incidence hole210amay be disposed to overlap the first long axis330of the exit surface300a. In this case, the second short axis length Dx2of the second short axis212is smaller than the first long axis length Dx1of the first long axis330.

Further, a center C4of the incidence hole210amay be disposed on the optical axis C, and the light source10may be disposed at a center of the incidence hole210a. Accordingly, an air layer may be disposed between the light source10and the incidence surface200a. Thus, light emitted from the light source10to the air layer may be refracted at the incidence surface200aof the light diffusion lens1chaving a different refractive index.

The exit surface300amay be a surface of the light diffusion lens1cfrom which the light incident through the incidence surface200ais emitted and may be formed to be rotationally symmetrical based on the optical axis C. Thus, as shown inFIG. 30, when viewed in the optical axis direction, the exit surface300amay be formed to have the first long axis330with the predetermined first long axis length Dx1and the first short axis340with the predetermined first short axis length Dy1. For example, the exit surface300amay be formed in an elliptical shape.

Further, a height H2of the exit surface300ais greater than the height H1of the incidence surface200abased on the optical axis direction.

Referring toFIGS. 31 and 32, the exit surface300amay include the convex-shaped top surface310aand the side surface320adisposed between the top surface310aand the bottom surface100a. In this case, the side surface320amay be disposed parallel to the optical axis C. Further, some of lights incident into the light diffusion lens1cthrough the incidence surface200ais refracted through the top surface310ato be emitted to the outside.

The top surface310amay be convexly formed in a non-hemispherical shape or a rotationally symmetrical shape. For example, the top surface310amay be convexly formed in the optical axis direction (the Z direction).

In this case, the top surface310amay be symmetrically formed based on an imaginary vertical flat surface passing through the optical axis C. For example, the top surface310amay implement a symmetrical optical path with respect to the first long axis330or the first short axis340based on the optical axis C.

The top surface310amay be formed in a convex shape of which curvature is gradually increased from a central portion of an uppermost end of the top surface310atoward an edge portion thereof. Alternatively, the central portion of the uppermost end of the top surface310amay be flatter than the edge portion thereof.

Meanwhile, the light diffusion lens1cmay implement asymmetric light distribution while improving light diffusivity and image quality using the side surface320awhich forms a free curve so as to generate a height difference on the upper side of the exit surface300a.

As shown inFIG. 28, since the upper side of the side surface320ais formed in a curved shape, the side surface320amay include a pair of first side portions321, each having a first height H3, and a pair of second side portions322, each having a second height H4. Here, the pair of first side portions321and the pair of second side portions322are respectively disposed to face each other based on the optical axis C. In this case, the first height H3is formed to be higher than the second height H4based on the bottom surface100aor an edge of a lower side of the side surface320a. Thus, the first height H3may be a maximum height of the side surface320a, and the second height H4may be a minimum height of the side surface320a.

Referring toFIGS. 30, 33, and 34, the first side portion321may be disposed in the short axis direction of the incidence hole210a, and the second side portion322may be disposed in the long axis direction of the incidence hole210a. Alternatively, the first side portion321may be disposed in the long axis direction of the exit surface300a, and the second side portion322may be disposed in the short axis direction of the exit surface300a.

At this time, in order to prevent formation of moire to improve light uniformity of the light diffusion lens1c, a ratio Hr between the first height H1of the first side portion321and the second height H2of the second side portion322may be designed in consideration of a ratio of the second short axis212to the second long axis211of the incidence hole210a.

Meanwhile, an area in which the top surface310aand the side surface320ameet may be formed in a curved shape. Here, the curved shape may be formed to have a predetermined curvature. As shown inFIG. 28, the upper side of the side surface320amay be formed in a curved shape in which the height of the side surface320ais decreased from the first side portion321toward the second side portion322.

The third protrusion600may be convexly formed toward the optical axis C. Accordingly, the third protrusion600may be called a second protruding portion or a second protrusion.

A plurality of third protrusions600may be formed on the incidence surface200a, and the sum of the plurality of third protrusions600may be 30% or less of an entire area of the incidence surface200a.

In embodiments, the plurality of third protrusions600are formed to have an area of 30% or less of the entire area of the incidence surface200a. When the third protrusions600have an area exceeding 30% of the entire area of the incidence surface200a, the third protrusions600affect overall image quality of the light diffusion lens1c. For example, since paths of reflected light and returned light are changed when the entire area of the plurality of third protrusions600increases, when the plurality of third protrusions600are applied, the sum of the entire area of the plurality of third protrusions600are less than or equal to 30% of the entire area of the incidence surface200a.

FIG. 36is a diagram illustrating an arrangement relationship between a light source and the light diffusion lens according to the fourth embodiment.

Referring toFIG. 36, since some of the lights emitted from the light source10may be emitted at a predetermined divergence angle θ based on the optical axis C, the third protrusion600is disposed within the divergence angle θ so that the light is refracted to the top surface310aof the exit surface300aand then emitted. Accordingly, the light diffusion lens1cmay secure light diffusivity and light uniformity by changing the optical path of some of the lights, which have directivity in a specific direction, through the third protrusion600. In this case, the divergence angle θ may be 50 degrees or less based on the optical axis C. In one embodiment, the third protrusion600is disposed within 50 degrees based on the optical axis C.

Referring toFIGS. 33 and 35, the third protrusion600may be formed of a third curved surface610which is formed of a curved surface in a vertical cross section. Thus, the third curved surface610may be convexly formed on the incidence surface200atoward the optical axis C.

Referring toFIG. 33, two third protrusions600may be symmetrically disposed based on the optical axis C in the vertical cross section. Accordingly, the light diffusion lens1cmay improve light uniformity in the long axis direction of the exit surface300a. Here, in consideration of the light emitted from the light source10, two or more or three or more third protrusions600may be disposed. Additionally, in consideration of light uniformity in the long axis direction of the exit surface300a, two third protrusions600may be symmetrically disposed based on the optical axis C.

Meanwhile, a cross section of the third protrusion600may be formed in an elliptical shape to protrude from the incidence surface200a. Accordingly, the third protrusion600may include a third long axis620with a predetermined third long axis length Dy3and a third short axis630with a predetermined third short axis length Dx3. Here, when the exit surface300ais viewed, the third short axis630of the third protrusion600may be disposed to overlap the first long axis330of the exit surface300a. In this case, the second short axis length Dx2of the second short axis212is greater than the third short axis length Dx3of the third short axis630. Further, a center C5of the third protrusion600, at which the third long axis620and the third short axis630meet, may be disposed in the long axis direction of the exit surface300a.

Referring toFIG. 28, an edge at which the third protrusion600and the incidence surface200ameet may be formed in an elliptical shape. Here, the edge at which the third protrusion600and the incidence surface200ameet may be called a third edge. In this case, a cross-sectional area of the third protrusion600may decrease toward the optical axis C. Thus, since the third protrusion600includes a maximum cross-sectional area at the edge, the third long axis length Dy3of the third long axis620and the third short axis length Dx3of the third short axis630become maximum at the edge.

The edge may include one point P5at a lower end and one point P6at an upper end based on the optical axis direction. Here, the one point P5at the lower end may be called a fifth point, and the one point P6at the upper end may be called a sixth point.

Referring toFIGS. 33 and 35, in embodiments, the third protrusion600is disposed within a predetermined available range based on the long axis direction of the exit surface300a. Here, the available range may indicate a range between a distance R7from the optical axis C to the one point P5at the lower end of the edge in the radial direction and a distance R8from the optical axis C to the one point P6at the upper end of the edge in the radial direction. In one embodiment, the available range may be a factor which indicates how far the third protrusion600is away from the optical axis C in the long axis direction of the exit surface300a.

Therefore, when the third protrusion600is disposed outside the available range, a dark portion and a bright portion are generated in an image due to internal reflection of the light diffusion lens1csuch that light uniformity may be degraded.

Consequently, the light diffusion lens1cmay secure the light uniformity by locating the third protrusion600within the available range.

As shown inFIG. 35, the distance R7from the optical axis C to the one point P5at the lower end of the edge may be formed to be greater than the distance R8from the optical axis C to the one point P6at the upper end of the edge. Further, the distance R7from the optical axis C to the one point P5at the lower end of the edge may be formed to be smaller than half of the second short axis length Dx2of the incidence hole210a.

Therefore, the light diffusion lens1cmay define the distance R7from the optical axis C to the one point P5at the lower end of the edge and the distance R8from the optical axis C to the one point P6at the upper end of the edge based on the half of the second short axis length Dx2of the incidence hole210a, thereby presenting an arrangement position of the third protrusion600.

Here, the half of the second short axis length Dx2of the incidence hole210amay be 9.9 to 10.0 times a difference R7-R8between the distance R7from the optical axis C to the one point P5at the lower end of the edge and the distance R8from the optical axis C to the one point P6at the upper end of the edge. Specifically, the half of the second short axis length Dx2of the incidence hole210amay be 9.95 times the difference R7-R8between the distance R7from the optical axis C to the one point P5at the lower end of the edge and the distance R8from the optical axis C to the one point P6at the upper end of the edge.

Meanwhile, the one point P6at the upper end of the edge may be disposed above an imaginary line L passing through a center C2of the height H1of the incidence surface200ain a horizontal direction based on the optical axis direction. In this case, the line L may be disposed above the side surface320a.

FIG. 37shows photographs illustrating before and after application of a third protrusion. Here,FIG. 37Ais a diagram illustrating light formed by a light diffusion lens in which a third protrusion is omitted from the light diffusion lens according to the fourth embodiment, andFIG. 37Bis a diagram illustrating light formed by the light diffusion lens, to which the third protrusion is applied, according to the fourth embodiment.

Lights incident into the third protrusion600may be refracted by the third protrusion600to improve light uniformity of the light diffusion lens1c. For example, the lights incident into the third protrusion600may be collected by the third protrusion600and refracted to the top surface310. For example, the third protrusion600may serve as a converging lens.

Thus, as shown inFIG. 37A, when the third protrusion is omitted from the light diffusion lens according to the fourth embodiment, a dark portion is formed. However, as shown inFIG. 37B, when the third protrusion600is applied to the light diffusion lens1caccording to the fourth embodiment, it can be confirmed that the dark portion is removed or minimized such that light uniformity is improved.

In this case, a five surface emission LED may be used as the light source10. Accordingly, the third protrusion600is disposed in the same radial direction to correspond to a side light-emitting surface12such that the light uniformity may be improved.

Fifth Embodiment

FIG. 38is a perspective view illustrating a light diffusion lens according to a fifth embodiment,FIG. 39is a bottom view illustrating the light diffusion lens according to the fifth embodiment,FIG. 40is a plan view illustrating the light diffusion lens according to the fifth embodiment,FIG. 41is a front view illustrating the light diffusion lens according to the fifth embodiment,FIG. 42is a side view illustrating the light diffusion lens according to the fifth embodiment,FIG. 43is a cross-sectional view in a long axis direction based on an exit surface of the light diffusion lens according to the fifth embodiment,FIG. 44is a cross-sectional view in a short axis direction based on the exit surface of the light diffusion lens according to the fifth embodiment,FIG. 45is an enlarged view illustrating area F ofFIG. 43, andFIG. 46is a diagram illustrating an arrangement relationship between a light source and the light diffusion lens according to the fifth embodiment. Here,FIG. 43is a cross-sectional view taken along line A6-A6ofFIG. 38, andFIG. 44is a cross-sectional view taken along line A7-A7ofFIG. 38.

In describing a light diffusion lens1daccording to the fifth embodiment, the same components as those of the light diffusion lens1caccording to the fourth embodiment are denoted by the same reference numerals, and thus detailed descriptions thereof will be omitted herein.

Comparing the light diffusion lens1daccording to the fifth embodiment with the light diffusion lens1caccording to the fourth embodiment, the light diffusion lens1daccording to the fifth embodiment is different from the light diffusion lens1cin that the third protrusions600are omitted and a plurality of fourth dimples700are included.

Referring toFIGS. 38 to 45, the light diffusion lens1daccording to the fifth embodiment may include a bottom surface100a, an incidence surface200aconcavely formed inward the bottom surface100ato form an incidence hole210a, an exit surface300afrom which light incident through the incidence surface200ais emitted, and the fourth dimples700concavely formed on the exit surface300a. Here, the exit surface300amay include a top surface310aand a side surface320a.

Therefore, the light diffusion lens1dmay diffuse light emitted from a light source10using the aspherical-shaped incidence surface200a, the exit surface300a, and the fourth dimples700formed on the exit surface300a.

In embodiments, in the light diffusion lens1d, since an optical path of the light emitted from the light source10is changed due to shapes of the incidence surface200aand the exit surface300aand the fourth dimples700, the shapes of the incidence surface200a, which is formed in the aspherical shape, and the exit surface300a, and arrangements, shapes, and sizes of the fourth dimples700act as largest factors of light distribution according to the change of the optical path of the light.

A plurality of fourth dimples700may be concavely formed on the top surface310aof the exit surface300atoward an optical axis C. Accordingly, each of the plurality of fourth dimples700may be called a second concave portion or a second groove.

Referring toFIG. 45, each of the plurality of fourth dimples700may be formed of a curved surface in a vertical cross section. For example, each of the plurality of fourth dimples700may be formed to be concave toward the optical axis C on the exit surface300a. In this case, a cross section of the fourth dimple700may be formed in an elliptical shape including a long axis and a short axis.

Referring toFIG. 40, the plurality of fourth dimples700may include a fourth-first dimple710formed at a predetermined radius R9from the optical axis C, a fourth-second dimple720formed at a predetermined radius R10from the optical axis C, and two or more fourth-third dimples730disposed at a predetermined radius R11based on the optical axis C. Here, the fourth-first dimple710and the fourth-second dimple720may be disposed to be spaced apart from each other in the same radial direction of a first long axis330of the exit surface300a. Further, the radius R11of the fourth-third dimple730is smaller than the radius R9of the fourth-first dimple710and is greater than the radius R10of the fourth-second dimple720.

The fourth-first dimple710may include a fourth-first long axis711with a predetermined fourth-first long axis length Dy4-1and a fourth-first short axis712with a predetermined fourth-first short axis length Dx4-1. Here, the fourth-first long axis length Dy4-1may be called a long axis length of the fourth-first dimple710, and the fourth-first short axis length Dx4-1may be called a short axis length of the fourth-first dimple710. In this case, the fourth-first long axis length Dy4-1is greater than the fourth-first short axis length Dx4-1.

Further, a center C6of the fourth-first dimple710may be disposed at an intersection at which the fourth-first long axis711and the fourth-first short axis712meet. Accordingly, the radius R9of the fourth-first dimple710may be a distance from the optical axis C to the center C6of the fourth-first dimple710.

Further, when the exit surface300ais viewed in the optical axis direction, the fourth-first short axis712of the fourth-first dimple710may be disposed to overlap the first long axis330of the exit surface300a.

The fourth-second dimple720may include a fourth-second long axis721with a predetermined fourth-second long axis length Dy4-2and a fourth-second short axis722with a predetermined fourth-second short axis length Dx4-2. Here, the fourth-second long axis length Dy4-2may be called a long axis length of the fourth-second dimple720, and the fourth-second short axis length Dx4-2may be called a short axis length of the fourth-second dimple720. In this case, the fourth-second long axis length Dy4-2is greater than the fourth-second short axis length Dx4-2.

Further, a center C7of the fourth-second dimple720may be disposed at an intersection at which the fourth-second long axis721and the fourth-second short axis722meet. Accordingly, the radius R10of the fourth-second dimple720may be a distance from the optical axis C to the center C7of the fourth-second dimple720.

Further, when the exit surface300ais viewed in the optical axis direction, the fourth-second short axis722of the fourth-second dimple720may be disposed to overlap the first long axis330of the exit surface300a.

The fourth-third dimple730may include a fourth-third long axis731with a predetermined fourth-third long axis length Dy4-3and a fourth-third short axis732with a predetermined fourth-third short axis length Dx4-3. Here, the fourth-third long axis length Dy4-3may be called a long axis length of the fourth-third dimple730, and the fourth-third short axis length Dx4-3may be called a short axis length of the fourth-third dimple730. In this case, the fourth-third long axis length Dy4-3is greater than the fourth-third short axis length Dx4-3.

Further, a center C8of the fourth-third dimple730may be disposed at an intersection at which the fourth-third long axis731and the fourth-third short axis732meet. Accordingly, the radius R11of the fourth-third dimple730may be a distance from the optical axis C to the center C8of the fourth-third dimple730.

Further, when the exit surface300ais viewed in the optical axis direction, the fourth-third short axis732of the fourth-third dimple730is not disposed to overlap the first long axis330of the exit surface300a.

Here, the fourth-third long axis length Dy4-3of the fourth-third dimple730may be smaller than the fourth-first long axis length Dy4-1of the fourth-first dimple710and greater than the fourth-second long axis length Dy4-2of the fourth-second dimple720.

Referring toFIG. 40, the radius R9to the center C6of the fourth-first dimple710and the radius R10to the center C7of the fourth-second dimple720are greater than the radius R11to the center C8of the fourth-third dimple730based on the optical axis C.

Referring toFIG. 40, the center C6of the fourth-first dimple710and the centers C8of the two fourth-third dimples730may be formed in a triangular shape including an imaginary first area. Further, the center C7of the fourth-second dimple720and the centers C8of the two fourth-third dimples730may be formed in a triangular shape including an imaginary second area. In this case, the imaginary first area is greater than the imaginary second area.

Meanwhile, the fourth-first dimple710, the fourth-second dimple720, and the two fourth-third dimples730may form one group. Further, as shown inFIG. 40, the light diffusion lens1dmay include two groups facing each other based on the optical axis C, and the two groups may be symmetrically disposed based on the optical axis C.

Accordingly, in the light diffusion lens1d, the plurality of fourth dimples700may be formed in at least two groups which are symmetrical based on the optical axis C. Accordingly, the light diffusion lens1dmay improve light uniformity in the long axis direction of the exit surface300a. Here, in consideration of the light emitted from the light source10, two or more or three or more groups of the plurality of fourth dimples700may be disposed. Additionally, in consideration of optical uniformity, two or more even numbers of groups of the plurality of fourth dimples700may be disposed to face each other based on the optical axis C.

Referring toFIG. 46, since some of the lights emitted from the light source10may be emitted at a predetermined divergence angle θ based on the optical axis C, the plurality of fourth dimples700are disposed within the divergence angle θ so that the light is refracted to be emitted. Accordingly, the light diffusion lens1dmay secure light diffusivity and light uniformity by changing the optical path of some of the lights, which have directivity in a specific direction, through the fourth dimple700. In this case, the divergence angle θ may be 50 degrees or less based on the optical axis C. Specifically, since the fourth-first dimple710of the fourth dimple700is disposed at an outermost side based on the optical axis C, the center C6of the fourth-first dimple710may be disposed at an angle ranging from 34 degrees to 40 degrees based on the optical axis C. Preferably, the center C6of the fourth-first dimple710of the fourth dimple700may be disposed at an angle of 37 degrees based on the optical axis C.

Referring toFIGS. 38 and 40, edges at which the plurality of fourth dimples700and the exit surface300ameet may be formed in an elliptical shape. Here, the edge at which the fourth dimple700and the exit surface300ameet may be called a third edge.

Referring toFIGS. 43 and 45, the edge at which the fourth dimple700and the exit surface300ameet may include one point at a lower end and one point at an upper end based on the optical axis direction. Here, the one point at the lower end of the fourth dimple700may be the center C6of the fourth-first dimple710, and the one point at the upper end of the fourth dimple700may be the center C7of the fourth-second dimple720.

Referring toFIG. 45, in embodiments, the fourth dimple700is disposed within a predetermined available range based on the long axis direction of the exit surface300a. Here, the available range may indicate a range between a radius R9from the optical axis C to the center C6of the fourth-first dimple710in the long axis direction and a radius R10from the optical axis C to the center C7of the fourth-second dimple720in the long axis direction.

Therefore, when the fourth dimple700is disposed outside the available range, a dark portion and a bright portion are generated in an image due to external refraction of the light diffusion lens1dsuch that light uniformity may be degraded.

Consequently, the light diffusion lens1dmay secure the light uniformity by locating the fourth dimple700within the available range.

As shown inFIG. 45, the radius R9from the optical axis C to may be formed to be greater than the radius R10therefrom. Further, the radius R10may be formed to be greater than half of a second short axis length Dx2of the incidence hole210a.

FIG. 47shows photographs illustrating before and after application of a fourth dimple. Here,FIG. 47Ais a diagram illustrating light formed by a light diffusion lens in which a fourth dimple is omitted from the light diffusion lens according to the fifth embodiment, andFIG. 47Bis a diagram illustrating light formed by the light diffusion lens, to which the fourth dimple is applied, according to the fifth embodiment.

Lights incident into the fourth dimple700may be refracted by the fourth dimple700to improve light uniformity of the light diffusion lens1d. For example, the lights incident into the fourth dimple700may diverge by the fourth dimple700to be diffused to the outside. For example, the fourth dimple700may serve as a diverging lens.

Thus, as shown inFIG. 47A, when the fourth dimple is omitted from the light diffusion lens according to the fifth embodiment, a bright portion is formed. However, as shown inFIG. 47B, when the fourth dimple700is applied to the light diffusion lens1daccording to the fifth embodiment, it can be confirmed that the bright portion is improved such that light uniformity is improved.

In this case, a five surface emission LED may be used as the light source10. Accordingly, the fourth dimple700is disposed in the same radial direction to correspond to a side light-emitting surface12such that the light uniformity of the light diffusion lens1dmay be improved.

Sixth Embodiment

FIG. 48is a perspective view illustrating a light diffusion lens according to a sixth embodiment,FIG. 49is a bottom view illustrating the light diffusion lens according to the sixth embodiment,FIG. 50is a plan view illustrating the light diffusion lens according to the sixth embodiment,FIG. 51is a front view illustrating the light diffusion lens according to the sixth embodiment,FIG. 52is a side view illustrating the light diffusion lens according to the sixth embodiment,FIG. 53is a cross-sectional view in a long axis direction based on an exit surface of the light diffusion lens according to the sixth embodiment,FIG. 54is a cross-sectional view in a short axis direction based on the exit surface of the light diffusion lens according to the sixth embodiment,FIG. 55is an enlarged view illustrating area G ofFIG. 53, andFIG. 56is a diagram illustrating an arrangement relationship between a light source and the light diffusion lens according to the sixth embodiment. Here,FIG. 53is a cross-sectional view taken along line A8-A8ofFIG. 48, andFIG. 54is a cross-sectional view taken along line A9-A9ofFIG. 48.

In describing a light diffusion lens1eaccording to the sixth embodiment, the same components as those of the light diffusion lens1caccording to the fourth embodiment and the light diffusion lens1daccording to the fifth embodiment are denoted by the same reference numerals, and thus detailed descriptions thereof will be omitted herein.

Comparing the light diffusion lens1eaccording to the sixth embodiment with the light diffusion lens1caccording to the fourth embodiment, the light diffusion lens1eaccording to the sixth embodiment is different from the light diffusion lens1cin that a plurality of fourth dimples700are further included.

Referring toFIGS. 48 to 55, the light diffusion lens1eaccording to the sixth embodiment may include a bottom surface100a, an incidence surface200aconcavely formed inward the bottom surface100ato form an incidence hole210a, an exit surface300afrom which light incident through the incidence surface200ais emitted, third protrusions600convexly formed on the incidence surface200a, and the fourth dimples700concavely formed on the exit surface300a. Here, the exit surface300amay include a top surface310aand a side surface320a.

Therefore, the light diffusion lens1emay diffuse light emitted from a light source10using the aspherical-shaped incidence surface200a, the exit surface300a, the third protrusions600formed on the incidence surface200a, and the fourth dimples700formed on the exit surface300a.

In embodiments, in the light diffusion lens1e, since an optical path of the light emitted from the light source10is changed due to shapes of the incidence surface200aand the exit surface300a, the third protrusions600, and the fourth dimples700, the shapes of the incidence surface200a, which is formed in the aspherical shape, and the exit surface300a, and arrangements, shapes, and sizes of the fourth dimples700act as largest factors of light distribution according to the change of the optical path of the light. In this case, the fourth dimple700may be formed to correspond to light which is refracted due to the third protrusion600.

The third protrusion600may be convexly formed on the incidence surface200atoward the optical axis C, and the fourth dimple700may be concavely formed on the top surface310aof the exit surface300atoward the optical axis C.

Referring toFIG. 56, since some of the lights emitted from the light source10may be emitted at a predetermined divergence angle θ based on the optical axis C, the third protrusion600and the fourth dimple700are disposed within the divergence angle θ so that the light is refracted to be emitted. Accordingly, the light diffusion lens1emay secure light diffusivity and light uniformity by changing the optical path of some of the lights, which have directivity in a specific direction, through the third protrusion600and the fourth dimple700. In this case, the divergence angle θ may be 50 degrees or less based on the optical axis C.

In this case, a divergence angle applied to arrange the fourth dimple700based on the optical axis C may be smaller than a divergence angle for application of the third protrusion600. In one embodiments, as shown inFIG. 56, the fourth dimple700may be disposed close to the optical axis C based on the divergence angle for application of the third protrusion600.

Referring toFIG. 53, the third protrusions600and the fourth dimples700may be respectively symmetrically disposed based on the optical axis C in a vertical cross section. Accordingly, the light diffusion lens1emay improve light uniformity in a long axis direction of the exit surface300a. Here, in consideration of the light emitted from the light source10, two or more or three or more third protrusions600and two or more or three or more fourth dimples700may be disposed, respectively. Additionally, in consideration of light uniformity in the long axis direction of the exit surface300a, groups of two third protrusions600and two fourth dimples700may be respectively disposed to face each other based on the optical axis C.

Here, the exit surface300amay be formed to have a first long axis330with a predetermined first long axis length Dx1and a first short axis340with a predetermined first short axis length Dy1. The third protrusion600may be disposed in the same direction as the first long axis330. Accordingly, a third short axis630of the third protrusion600may be disposed to overlap the first long axis330of the exit surface300a.

Further, a plurality of fourth dimples700may include a fourth-first dimple710, a fourth-second dimple720, and two fourth-third dimples730. A fourth-first short axis712of the fourth-first dimple710and a fourth-second short axis722of the fourth-second dimple720may be disposed to overlap the first long axis330of the exit surface300a.

Thus, when the exit surface300ais viewed in the optical axis direction, the third short axis630, the fourth-first short axis712of the fourth-first dimple710, and the fourth-second short axis722of the fourth-second dimple720may be disposed to overlap the first long axis330of the exit surface300a.

Meanwhile, a third long axis length Dy3of a third long axis620of the third protrusion600may be greater than a fourth-first long axis length Dy4-1of a fourth-first long axis711of the fourth-first dimple710.

Further, lights incident into the third protrusion600may be collected by the third protrusion600and incident into the fourth dimple700. Further, the lights incident into the fourth dimple700may be diffused by the fourth dimple700and emitted to the outside.

Consequently, the light diffusion lens1emay further improve light uniformity by applying the fourth dimple700to an area of a minute dark portion or a minute bright portion which is not resolved through the application of the third protrusion600.

Meanwhile, a five surface emission LED may be used as the light source10. Accordingly, a plurality of the third protrusions600and the plurality of the fourth dimples700are disposed in the same direction to correspond to a side light-emitting surface12such that the light uniformity of the light diffusion lens1emay be improved.

As described above, in accordance with the present disclosure, there is an effect in that light diffusivity and light uniformity can be secured by changing an optical path of a part of light having directivity in a specific direction using dimples formed on an incidence surface or an exit surface.

Further, in accordance with the present disclosure, there is an effect in that light uniformity can be improved by removing or minimizing a dark portion due to light distribution using a dimple formed on the incidence surface and can be improved by removing or minimizing the dark portion or a bright portion using a dimple formed on the exit surface.

As discussed in the foregoing, although all the elements forming the embodiments of the present disclosure are combined into one or operated as one element, the present disclosure is not limited thereto. That is, all the elements may be selectively combined or operated if within an object scope of the present disclosure. Furthermore, it will be understood that the terms “includes” and/or “including”, “forming” and/or “formed” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.