Abstract:
A light-emitting diode (LED) includes s a substrate, a LED chip, and an optical lens. The LED chip is fixedly mounted to the substrate for emitting a light beam. The optical lens is mounted to the substrate and covers the LED chip. The optical lens has a light exit surface, which directs the light beam from the LED chip to travel in a direction along an optical axis to form a non-symmetric light shape. Also disclosed is a surveillance camera device that uses the LED. As such, the drawback of a conventional surveillance camera being incapable of acquiring an excellent image due to light source being overly concentrated can be eliminated.

Description:
CROSS-REFERENCE TO OTHER APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 14/974,359, filed on Dec. 18, 2015 and entitled ILLUMINATION MODULE FOR CREATING LATERAL RECTANGULAR ILLUMINATION WINDOW, which claims priority to Europe Patent Application No. EP16191833.9, filed on Sep. 30, 2016, the complete subject matter of both which are hereby incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a light-emitting diode (LED), and in particular to a light-emitting diode for use in an imaging system and a surveillance camera device using the light-emitting diode. 
       BACKGROUND OF THE INVENTION 
       [0003]    Security surveillance systems are very widely used in areas, where surveillance is necessary, such as factories, dormitories, stores, entrances of buildings and community housings, or secret and hidden places, where people rarely go, so that the security surveillance systems may make recording of instantaneous image information by means of transmitter modules and receiver modules thereof (including lighting modules and imaging systems). 
         [0004]    A common problem of using the security surveillance system in nighttime is that lighting is insufficient and the image gets unclear and blurring. The security surveillance system is often built in with a lighting module including an infrared light-emitting diode or an infrared laser source in order to allow the imaging system to acquire a clear image thereby allowing the security surveillance system to carry out effective surveillance even in a light-insufficient area. However, a regular light-emitting diode or laser source usually generates a light shape that is an isotropic circular-symmetry light shape, in which light intensity in a central zone is far greater than that at a peripheral zone so that an edge of an image becomes relatively dark with inhomogeneous lighting brightness, whereby the security surveillance may not retrieve clear image information of an object located in the peripheral zone of an acquired image. 
         [0005]    Referring to  FIG. 14 a   , which is a schematic view illustrating image information acquired with a conventional surveillance camera device, a regular light-emitting diode or laser source usually generates a light shape that is a circular-symmetry light shape, in which light intensity in a central zone is often far greater than that at a peripheral zone so that the camera cannot clearly photograph an object located in the peripheral zone of an imaged area. Thus, a dark zone A appears in the peripheral zone of the image information. For instance,  FIGS. 16 a  to 16 d    show a variety of the half-power view angles of the circular-symmetry light shape (which is a light angle that light intensive value is half of the intensive value of the axis direction) of the light receiving plane homogeneity diagrams, wherein the half-power view angles are 120, 90, 60 and 45 degrees in sequence, which shows the light are centralized in the center portion. 
         [0006]    Referring to  FIG. 14 b   , which is another schematic view illustrating image information acquired with a conventional surveillance camera device, to match a specific image aspect ratio (such as 4:3) acquired with the camera, a known lens mechanism usually has a rectangular opening. This arrangement may lead to a great loss of optical energy E and results in poor coverage so that an image of a photographed object is trimmed by the rectangular opening, causing distortion of a portion of the image. 
         [0007]    Thus, to improve object image information retrieved from the peripheral zone by the security surveillance system, the known designs of the security surveillance systems often involve a large number of lighting modules, such as infrared light-emitting diodes and infrared laser sources to enhance brightness for optical lenses, or more than one optical devices are used, such as optical lenses or reflectors, in order to conduct optical adjustment through reflection and refraction of light to thereby enhance clarity and sharpness of a surveillance image, wherein air or other filling materials that are different from the materials of the optical devices are present between the optical devices and the lighting modules. Such optical devices are so called secondary optical devices. As shown in  FIG. 15 , which is a schematic view illustrating a known surveillance camera device mounted to a ceiling, the known camera device  5  is attached to a ceiling  6  and the camera device  5  comprises a casing  51 , an image capturing element  52 , and at least one light supplementing structure  53 . The light-supplementing structure  53  comprises a light reflector  531  and a light emission module  532  and uses multiple reflection surfaces  5311 ,  5312  of the light reflector  531  to convert, through light reflection, circular-symmetry light generated by the light emission module  532  to generate a special light shape fit to the camera device  5  so as to increase illumination on the ceiling  6  and in an area under the ceiling  6  and to enhance clarity of an image captured by the image capturing element  52  thereby eliminating the problem that no high quality image can be acquired by the camera device  5  due to insufficient illumination. However, such an arrangement still suffers the following problems: 
         [0008]    (1) Since the secondary optical arrangement uses reflection and refraction of light to generate non-symmetric light shape, the overall lighting efficiency deteriorates due to multiple times of reflection and refraction of light. During an operation of the surveillance device in nighttime, in order to meet the illumination required for nighttime imaging, the illumination must be increased due to loss caused by multiple time of reflection and refraction and thus, power consumption of the security surveillance system becomes excessively high. 
         [0009]    (2) Although design difficulty of a secondary optical arrangement is low for there are multiple optical design parameters involved, yet positional shift may readily occur during an assembly process of the optical elements and the light emission modules. In addition to difficulty of assembly and increased manufacturing cost due to complicated parts involved, the size of the surveillance camera device may get bulky so that thinning and miniaturization are not possible. 
         [0010]    Thus, it is one of the issues that need to be overcome by those devoted themselves in research and study in this field to increase illumination, homogeneity, and coverage of a surveillance camera in order to acquire excellent imaging result and also to lower down power consumption and reduce the size of the surveillance camera. 
       SUMMARY OF THE INVENTION 
       [0011]    In view of the above problems, the primary objective of the present invention is to provide a light-emitting diode and a surveillance camera device that uses the light-emitting diode, wherein the light-emitting diode may directly generate an illumination area that is a homogeneous and non-symmetric light shape to be directly used in a surveillance camera device without involving secondary optical devices to increase homogeneity and illumination coverage of an image acquired by the surveillance camera and to shrink a dark zone of an image captured by the surveillance camera, and also to reduce optical loss of light caused by secondary optical devices thereby greatly reducing the size and power consumption of the surveillance camera device and achieving an effect of saving manufacturing cost and electrical power. 
         [0012]    To achieve the above objective, the present invention adopts a technical solution that is a light-emitting diode (LED), which comprises a substrate, a LED chip, an optical lens, and a wiring layer. The substrate has an installation surface; the wiring layer is formed on the installation surface; the LED chip has an optical axis and is fixedly mounted on the installation surface and is in electrical connection with the wiring layer; and the optical lens is fixedly mounted to the installation surface and encapsulates the LED chip, wherein the optical lens is formed to comprise a light exit surface, wherein a large width extension direction of the light exit surface is defined as an X-axis direction; a small width extension direction of the light exit surface is defined as a Y-axis direction, the X-axis direction and the Y-axis direction being perpendicular to each other; and a direction perpendicular to the installation surface is defined as a Z-axis direction, wherein the light exit surface protrudes from the installation surface in the Z-axis direction and the light exit surface is formed of at least two curved surfaces having different curvatures and is provided to direct a light beam emitting from the LED chip to travel in a direction along the optical axis to project onto a light receiving plane and forming a non-symmetric light shape, wherein the non-symmetric light shape is roughly a rectangle or an ellipse. 
         [0013]    Further, the wiring layer is made of a material selected from gold, silver, and copper, or an alloy thereof. 
         [0014]    Further, the non-symmetric light shape has an aspect ratio between 1.51 and 1.6. 
         [0015]    Further, the light exit surface further comprises a divergent surface and a convergent surface. 
         [0016]    Further, the LED chip generates visible light having white light color temperature between 2700K and 7000K. 
         [0017]    Further, the LED chip generates ultraviolet light having a wavelength between 365 and 405 nm. 
         [0018]    Further, the LED chip generates ultraviolet light having a wavelength of 365 nm. 
         [0019]    Further, the LED chip generates ultraviolet light having a wavelength of 385 nm. 
         [0020]    Further, the LED chip generates ultraviolet light having a wavelength of 395 nm. 
         [0021]    Further, the LED chip generates ultraviolet light having a wavelength of 405 nm. 
         [0022]    Further, the LED chip generates infrared light having a wavelength between 750 and 1000 nm. 
         [0023]    Further, the LED chip generates infrared light having a wavelength between 790 and 830 nm. 
         [0024]    Further, the LED chip generates infrared light having a wavelength between 830 and 870 nm. 
         [0025]    Further, the LED chip generates infrared light having a wavelength between 900 and 1000 nm. 
         [0026]    Further, the LED chip comprises a laser emitting semiconductor that generates infrared light having a wavelength between 800 and 1000 nm. 
         [0027]    Further, the number of the at least one LED chip is one and the at least one LED chip has a shape of square. 
         [0028]    Further, the number of the at least one LED chip is plural arranged to form a light emission array, wherein the light emission array has a shape of square and the LED chips of the light emission array are arranged in a tight arrangement. 
         [0029]    Further, the LED chips are spaced from each other by a spacing distance between 0.0508 and 0.1016 mm. 
         [0030]    Further, the substrate comprises a metal substrate, a ceramic substrate, or a glass fiber substrate. 
         [0031]    Further, the metal substrate is made of a material selected from copper, copper alloy, aluminum, aluminum alloy, magnesium alloy, aluminum silicon carbide, and carbon composition. 
         [0032]    Further, the ceramic substrate is made of a material selected from aluminum oxide, aluminum nitride, zirconium oxide, silicon carbide, hexagonal boron nitride, and fluorinated carbon. 
         [0033]    Further, the optical lens has no air gap with respect to the substrate and the at least one LED chip. 
         [0034]    Further, the optical lens is asymmetric. 
         [0035]    Further, the light exit surface of the optical lens is selected from an aspheric surface, a cambered surface, a parabolic surface, a hyperbolic surface, and a free-form surface. 
         [0036]    Further, the optical lens satisfies the following condition 1: 
         [0000]      0.3 &lt;D 1 /D 2≦3   [condition 1]
 
         [0037]    wherein D1 is the widthwise distance between two outermost side edges of the light exit surface along the Y-axis, and D2 is the lengthwise distance between two opposite ends of the light exit surface along the X-axis. 
         [0038]    Further, the optical lens satisfies the following condition 2: 
         [0000]      0.1 ≦L 1 /D 1≦0.5; 0.1 ≦D 2 /D 2≦0.5   [condition 2]
 
         [0039]    wherein D1 is the widthwise distance between two outermost side edges of the light exit surface along the Y-axis; D2 is the lengthwise distance between two opposite ends of the light exit surface along the X-axis; L1 is a widthwise distance of the LED chip along the Y-axis; and L2 is a lengthwise distance of the LED chip along the X-axis. 
         [0040]    Further, the optical lens further satisfies the following condition 3: 
         [0000]      0.65 &lt;D 3/ D 4&lt;1   [condition 3]
 
         [0041]    wherein D3 is a distance from the installation surface to a lowest surface of the divergent surface in a direction along the optical axis, and D4 is a distance from the installation surface to a highest surface of the convergent surface in a direction along the optical axis. 
         [0042]    Further, the equation of the aspheric surface is as follows: 
         [0000]    
       
         
           
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         [0043]    where c denotes curvature, r indicates radius of curvature of an apex, and k indicate conic constant, and c=1/r and k=−0.522, and r=9.03. 
         [0044]    Further, the light exit surface of the optical lens is such that a light shape passing through the X-axis is a bat-wing shape having a half-power view angle between 40 and 160 degrees and a light shape passing through Y-axis is an axis-symmetric light shape or a bat-wing shape having a half-power view angle between 30 and 100 degrees. 
         [0045]    Further, when the light exit surface of the optical lens is a free-form surface, a light shape passing through the X-axis is a bat-wing shape having a half-power view angle of 130 degrees and a light shape passing through Y-axis is an axis-symmetric light shape or a bat-wing shape having a half-power view angle of 85 degrees. 
         [0046]    Further, when the light exit surface of the optical lens is an aspheric surface, a light shape passing through the X-axis is an axis-symmetric light shape having a half-power view angle of 47 degrees and a half-power view angle of the Y-axis is 31 degrees. 
         [0047]    Further, the optical lens is formed of a material selected from epoxy resin, acrylic resin, silicon resin, and silicone. 
         [0048]    Further, the optical lens has a refractive index of 1.4˜1.6. 
         [0049]    The present invention discloses a surveillance camera device that comprises a casing, at least one of the above-described LED, and an image capturing element, the image capturing element capturing an image, wherein the at least one LED is arranged at one side of the image capturing element because light generated by the LED can be directly and homogeneously distributed in a photographing range of the image capturing element so as to prevent the surveillance camera from being incapable of capturing a good image due to insufficiency of light intensity in a local area. 
         [0050]    The efficacy of the present invention is that the present invention is applicable to a security surveillance system. A light-emitting diode according to the present invention adopts package optical design to allow for direct projection of light shape of a non-symmetric configuration for matching an imaging system of the security surveillance system, without the need of additional optical elements for secondary optic design thereby effectively improving utilization performance of the light source, simplifying parts design of the security surveillance system to reduce the number of other optic elements involved and thus reducing the overall size of the security surveillance system and also to reduce distortion of image compression and conversion. The light exit surface of the optical lens allows for effective adjustment of the light shape projecting from the LED chip to directly form a non-symmetric light shape and to ensure excellent illuminated image for the surveillance camera device of the security surveillance system and to reduce loss of luminous intensity caused by secondary optics to thereby achieve an effect of energy saving by reducing power consumption. Thus, the present invention can effectively improve the drawback of the security surveillance field that a non-symmetric light shape can only be formed with secondary optic designs so as to lower down the cost of development and design of security surveillance systems. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0051]    The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
           [0052]    The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof with reference to the drawings, in which: 
           [0053]      FIG. 1  is a perspective view showing a light-emitting diode according a first preferred embodiment of the present invention; 
           [0054]      FIG. 2  is a perspective view showing a light-emitting diode according a second preferred embodiment of the present invention; 
           [0055]      FIG. 3 a    is a top plan view showing the light-emitting diode according the first preferred embodiment of the present invention; 
           [0056]      FIG. 3 b    is a cross-sectional view showing the light-emitting diode according the first preferred embodiment of the present invention; 
           [0057]      FIG. 3 c    is another cross-sectional view showing the light-emitting diode according the first preferred embodiment of the present invention; 
           [0058]      FIG. 4  is a perspective view showing a light-emitting diode according a third preferred embodiment of the present invention; 
           [0059]      FIG. 5 a    is a polar luminous intensity distribution diagram of the light-emitting diode according the third embodiment of the present invention; 
           [0060]      FIG. 5 b    is another polar luminous intensity distribution diagram of the light-emitting diode according the third embodiment of the present invention; 
           [0061]      FIG. 6 a    is a plot illustrating homogeneity of a light exit surface of the third embodiment of the present invention; 
           [0062]      FIG. 6 b    is a schematic view illustrating a light exit ray of the third embodiment of the present invention; 
           [0063]      FIG. 7  is a perspective view showing a light-emitting diode according a fourth preferred embodiment of the present invention; 
           [0064]      FIG. 8 a    is a polar luminous intensity distribution of the light-emitting diode according the fourth embodiment of the present invention; 
           [0065]      FIG. 8 b    is another polar luminous intensity distribution of the light-emitting diode according the fourth embodiment of the present invention; 
           [0066]      FIG. 9 a    is a plot illustrating homogeneity of a light exit surface of the fourth embodiment of the present invention; 
           [0067]      FIG. 9 b    is a schematic view illustrating a light exit ray of the fourth embodiment of the present invention; 
           [0068]      FIG. 10  is a schematic planar view illustrating a surveillance camera device according to the first embodiment of the present invention; 
           [0069]      FIG. 11  is a schematic side-elevational view illustrating the surveillance camera device of  FIG. 10  mounted to a ceiling; 
           [0070]      FIG. 12  shows an imaging result of a surveillance camera device according to the third embodiment of the present invention; 
           [0071]      FIG. 13  shows an imaging result of a conventional surveillance camera device; 
           [0072]      FIG. 14 a    is a schematic view illustrating image information acquired with a conventional surveillance camera device; 
           [0073]      FIG. 14 b    is a schematic view illustrating image information acquired with a conventional surveillance camera device; 
           [0074]      FIG. 15  is a schematic view illustrating a conventional surveillance camera device mounted to a ceiling; and 
           [0075]      FIGS. 16 a  to 16 d    are a variety of the half-power view angles of the circular-symmetry light shape of the light receiving plane homogeneity diagrams generated by a conventional surveillance camera device. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0076]    Referring to  FIG. 1 , a schematic view is provided to show a light-emitting diode according to a first preferred embodiment of the present invention. The light-emitting diode according to the instant embodiment, generally designated at  10   a , comprises a substrate  101 , a light-emitting diode chip  102 , an optical lens  103 , and a wiring layer  104 . Specifically, the substrate  101  comprises an installation surface  1011  and the wiring layer  104  is formed on the installation surface  1011 . The wiring layer  104  is made of a material that comprises a metal, such as gold, silver, copper, or a combination thereof, and is made of gold in the instant embodiment, which increases reflectivity by 5%˜10%, wherein the installation surface  1011  is provided for mounting the light-emitting diode chip  102  thereon. In the instant embodiment, the substrate  101  can be but not limited to a metal substrate, a ceramic substrate, or a glass fiber substrate (for example, FR-4, FR-5, G-10, G-11, and so on), wherein the metal substrate is made of a material that is selected as one of copper, copper alloy, aluminum, aluminum alloy, magnesium alloy, aluminum silicon carbide, and carbon composition. The ceramic substrate is made of a material selected as one of aluminum oxide, aluminum nitride, zirconium oxide, silicon carbide, hexagonal boron nitride, and fluorinated carbon. Preferably, a heat sink (not shown) or a circuit board (not shown) is mounted on a surface of the substrate  101  that is opposite to the installation surface  1011  to dissipate heat from the light-emitting diode chip  102 , wherein the heat sink can be formed through die casting, aluminum extruding, and stamping and the circuit board can be a glass fiber board, an aluminum substrate, or a copper substrate. 
         [0077]    The light-emitting diode chip  102  has a shape that is square and has an optical axis  1034 . In the instant embodiment, the number of the light-emitting diode chip  102  is one that generates visible light having white light color temperature between 2700K and 7000K, infrared light having a wavelength between 800 and 1000 nm (for example, infrared light having a wavelength between 790 and 830 nm with a peak value being 810 nm, infrared light having a wavelength between 830 and 870 nm with a peak value being 850 nm, or infrared light having a wavelength between 900 and 1000 nm with a peak value being 940 nm), ultraviolet light having a wavelength between 365 and 405 nm, or a laser beam having a wavelength between 800 and 1000 nm. In other words, specific examples of the light-emitting diode chip  102  may include a light-emitting diode that emits visible light, a light-emitting diode that emits invisible light (such as infrared light and ultraviolet light), and a laser semiconductor chip. 
         [0078]    The optical lens  103  can be a curable sealer that is moisture resistant. The optical lens  103  is fixedly mounted on the installation surface  1011  of the substrate  101  to encapsulate the light-emitting diode chip  102 . To reduce light refraction and loss, the light-emitting diode  10  of the present invention adopts a primary optical design, meaning the optical lens  103  is integrally formed on the installation surface  1011  of the substrate  101  through overmolding and set in tight engagement with the light-emitting diode chip  102 . The overmolding of the method injects the material of the optical lens  103  into a chamber of a die first, inserts the light-emitting diode chip  102  mounted on the installation surface  1011 , heats the material of the optical lens  103  directly such that it is curable and then takes it out from the chamber of the die to shape. Alternatively, after the light-emitting diode chip  102  is mounted on the installation surface  1011 , deposing into the die, combining a top of the die and a bottom of the die by the hydraulic machine and vacuuming the die, deposing the material of the optical lens  103  on an entrance of the injecting channel, applying a pressure to the material of the optical lens  103  to enter every forming grooves along the injecting channel and heating the material of the optical lens  103  to be curable and takes it out from the chamber of the die to shape. By the method, the optical lens  103  has no air gap (i.e. single reflectivity) with respect to the substrate  101  and the light-emitting diode chip  102 . In other words, the optical lens  103  and the light-emitting diode chip  102  are not bonded to each other with adhesive so that the manufacturing process is simplified to greatly reduce cost and shorten fabrication time and also to prevent the issue of positional shift of the optical elements and lighting module during an assembly process and the gap between the optical element and the lighting module may generate more surface reflection or refraction so as to reduce the total amount of light that can be extracted. 
         [0079]    In the instant embodiment, the curable sealer can be selected from one of a transparent material having a refractive index of 1.4˜1.6, preferably 1.5, such as epoxy resin, acrylic resin, silicon resin, and silicone, but not limited thereto. 
         [0080]    Further, the optical lens  103  has a light exit surface  1032 . With a large width extension direction of the light exit surface  1032  defined as an X-axis direction, a small width extension direction of the light exit surface  1032  defined as a Y-axis direction, where the X-axis direction and the Y-axis direction are perpendicular, and a direction perpendicular to the installation surface  1011  defined as a Z-axis direction, then the light exit surface  1032  protrudes from the installation surface  1011  in the Z-axis direction. 
         [0081]    Further, the light exit surface  1032  is formed of at least two curved surfaces  1033  having different curvatures. As such, the light exit surface  1032  of the optical lens  103  may guide a light beam emitting from the light-emitting diode chip  102  to travel in a direction along the optical axis  1034  to project onto a light receiving plane  20  and also form a non-symmetric light shape  21 . It is noted that the non-symmetric light shape  21  has a shape that is approximately a rectangle or an ellipse. Preferably, the non-symmetric light shape  21  has an aspect ratio between 1.51 and 1.6. The term “aspect ratio” used herein refers to the ratio of a maximum cross-sectional dimension of the non-symmetric light shape with a maximum cross-sectional dimension perpendicular to the maximum cross-sectional dimension. 
         [0082]    The optical lens  103  is asymmetric. The light exit surface  1032  of the optical lens  103  is selected from an aspheric surface, a cambered surface, a parabolic surface, a hyperbolic surface, and a free-form surface. 
         [0083]    In a polar coordinate system, incident light I has a vector: 
         [0000]        I =(sin φ I  cos θ i , sin φ I  sin θ j , cos φ I   k )
 
         [0084]    Further, according to Snell&#39;s law, when light wave propagates from one medium to another medium, if the two media have different refractive indexes, then reflection may occur. Thus, a regular secondary optical design (φ I ″) is as follows: 
         [0000]      φ I   =φs−α 1+α2=φ I ″
 
         [0085]    while the primary optical design (φ I ′) involves propagation among two or more different media, so that φ I ′=φs and φ I ′&gt;φ I ″. 
         [0086]    Further, according to the following luminous flux formula 
         [0000]    
       
         
           
               
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         [0087]    It is known that when sin φ get larger, luminous flux gets larger and thus, when φ I =φ I ′=φs, sin φ I ′&gt;sin φ I ″. Thus, the optical energy of the non-symmetric light shape 21 generated by the primary optical design adopted in this invention is increased by 10%˜20% as compared to the optical energy of the secondary optics. 
       Second Embodiment 
       [0088]    Referring to  FIG. 2 , a perspective view is given to illustrate a light-emitting diode according to a second preferred embodiment of the present invention. As shown in  FIG. 2 , the light-emitting diode of the instant embodiment, generally designated at  10   b , comprises a substrate  101 , at least one light-emitting diode chip  102 , an optical lens  103 , and a wiring layer  104 . The instant embodiment is different from the first embodiment in that the number of the light-emitting diode chip  102  involved is plural and the plural light-emitting diode chips  102  are arranged in a square light emission array  102 ′ and the plural light-emitting diode chips  102  are arranged tightly close to each other. As shown in  FIG. 2 , an illumination module  10   b  comprises four light-emitting diode chips  102 , which are arranged in a square light emission array  102 ′ with every two light-emitting diode chips  102  in a row. Preferably, the light-emitting diode chips  102  are arranged such that a spacing distance therebetween is between 0.0508 mm and 0.10616 mm in order to prevent the light-emitting diode chips  102  from colliding each other during encapsulation due to excessively small spacing distance therebetween and thus maintaining a desired light shape of the light-emitting diode  10   b.    
         [0089]    Although in the light-emitting diode  10   b  illustrated in  FIG. 2 , a square light emission array  102 ′ is provided by including four light-emitting diode chips  102 , in other examples of the instant embodiment, the square light emission array  102 ′ may be formed of nine light-emitting diode chips  102  with every three arranged in a row, and the likes. Thus, the number of light-emitting diode chips  102  shown in  FIG. 2  is provided as an example for illustration and reference and is not intended to limit the scope of the present invention. 
         [0090]    Further referring to  FIG. 3 a   , a top plan view is given to illustrate the light-emitting diode according to the first embodiment of the present invention. The optical lens  103  satisfies the following condition 1: 
         [0000]      0.3 &lt;D 1/ D 2≦3   [condition 1]
 
         [0091]    wherein D1 is the widthwise distance between two outermost side edges of the light exit surface  1032  along the Y-axis, and D2 is the lengthwise distance between two opposite ends of the light exit surface  1032  along the X-axis. 
         [0092]    Further, the optical lens  103  and the light-emitting diode chips  102  satisfy the following condition 2: 
         [0000]      0.1 ≦L 1/ D 1≦0.5; 0.1 ≦L 2/ D 2≦0.5   [condition 2]
 
         [0093]    wherein D1 is the widthwise distance between two outermost side edges of the light exit surface  1032  along the Y-axis; D2 is the lengthwise distance between two opposite ends of the light exit surface  1032  along the X-axis; L1 is a widthwise distance of the light-emitting diode chips  102  along the Y-axis; and L2 is a lengthwise distance of the light-emitting diode chips  102  along the X-axis. 
         [0094]    Further referring to  FIG. 3 b   , a cross-sectional view is given to illustrate the light-emitting diode according to the first embodiment of the present invention, wherein  FIG. 3 b    is a view of a cross-section passing through the optical axis  1034  and extending toward opposite ends in the X-axis directions. The light exit surface  1032  is formed of a divergent surface  1036  and a convergent surface  1037 , and a middle portion of the light exit surface  1032  is the divergent surface  1036 , while two outer end portions of the divergent surface  1036  are the convergent surface  1037 . The convergent surface  1037  is generally of mirror symmetry. Further, the divergent surface  1036  is provided for diverging a light beam around the optical axis  1034  and is thus preferably a concave curved surface of a negative diopter design, while the convergent surface  1037  is provided for converging a large angle light beam and is thus preferably a convex curved surface of a positive diopter design. The term “diopter” as used herein refers to the power of an optical system for converging light or diverging light and D=(n′/S′)−(n/S)=n′/f′=n/f, where S′ denotes image distance, S denotes object distance, n′ is image space refractive index, n is object space refractive index, f′ is image space focus length, and f is object space focus length. Accordingly, the light exit surface  1032  is shaped as being raised at the two end portions and recessed at the middle portion, along the X-axis, such that the contour is approximately an M-shape or is exactly an M-shape. Further, the optical lens  103  also satisfies the following condition 3: 
         [0000]      0.65 &lt;D 3/ D 4&lt;1   [condition 3]
 
         [0095]    wherein D3 is a distance from the installation surface  1011  to a lowest surface of the divergent surface  1036  in a direction along the optical axis  1034 , and D4 is a distance from the installation surface  1011  to a highest surface of the convergent surface  1037  in a direction along the optical axis  1034 . 
         [0096]    Further referring to  FIG. 3 c   , another cross-sectional view is given to illustrate the light-emitting diode according to the first embodiment of the present invention.  FIG. 3 c    is a view of a cross-section extending in a direction normal to and perpendicular to the X-axis direction. The light exit surface  1032  is convex toward the optical axis  1034  at the middle thereof, and the contours extending toward two opposite ends in the Y-axis direction are approximately an arch shape, but not limited thereto. For example, the contours extending to the two opposite ends in the Y-axis direction may be of an M-shape. Thus, in the instant embodiment, the light exit  1032  of the optical lens  103  is made in an optical design that satisfies the above conditions so as to reduce total internal reflection of light to thereby effectively direct the light beam emitting from the light-emitting diode chips  102  toward the light receiving plane  20  to form a non-symmetric light shape  21  having high homogeneity and thus improve overall illumination and homogeneity, and compared to the secondary optical devices, in addition to an effect of miniaturization, the present invention allows the optical energy of the non-symmetric light shape  21  to increase by 10%˜20% compared to the optical energy of the secondary optics. Further, under the condition of enlarging or reducing the optical lens  103  in a proportional way or the specification of the light-emitting diode chips  102  is varied, the present invention still allows for direct emission of non-symmetric light shape  21  and keeping the non-symmetric light shape at a constant aspect ratio. 
       Third Embodiment 
       [0097]    Referring to  FIG. 4 , a schematic view is provided to show a light-emitting diode according to a third preferred embodiment of the present invention. The instant embodiment is applicable to an indoor security surveillance system. Additional reference being had to  FIGS. 3 a -3 c   , as shown in the drawings, the light-emitting diode, generally designated at  10   c , comprises a substrate  101 , a light-emitting diode chip  102 , an optical lens  103 , and a wiring layer  104 . Specifically, the substrate  101  comprises an installation surface  1011  and the wiring layer  104  is formed on the installation surface  1011 . The wiring layer  104  is made of a material that comprises a metal, such as gold, silver, copper, or a combination thereof, and in the instant embodiment, the wiring layer is made of gold t, which increases reflectivity by 5%˜10%. The light-emitting diode chip  102  has a shape that is square and may generate infrared light having a wavelength between 750 and 1000 nm (for example, infrared light having a wavelength between 790 and 830 nm with a peak value being 810 nm, infrared light having a wavelength between 830 and 870 nm with a peak value being 850 nm, or infrared light having a wavelength between 900 and 1000 nm with a peak value being 940 nm). In the instant embodiment, the size of the light-emitting diode chip  102  is 20 mil., and may not be limited thereto and may be or example one of 30, 42, and 45 mil. The optical lens  103  is shaped to include a light exit surface  1032 . With a large width extension direction of the light exit surface  1032  defined as an X-axis direction, a small width extension direction of the light exit surface  1032  defined as a Y-axis direction, where the X-axis direction and the Y-axis direction are perpendicular, and a direction perpendicular to the installation surface  1011  defined as a Z-axis direction, then the light exit surface  1032  protrudes from the installation surface  1011  in the Z-axis direction. The light exit surface  1032  is formed of at least two curved surfaces  1033  of different curvatures. In the instant embodiment, the light exit surface  1032  of the optical lens  103  is a free-form surface, wherein D1 is approximately 3.0 mm, D2 is approximately 3.2 mm, D3 is approximately 1.53 mm, D4 is approximately 1.54 mm, and L1=L2=0.508 mm. Inserting these data into the conditions provided above in association with  FIGS. 3 a -3 c    provides the following conditions: 
         [0000]        D 1/ D 2=0.9375   [condition 1]
 
         [0000]        L 1/ D 1=0.1693;  L 2/ D 2=0.15875   [condition 2]
 
         [0000]        D 3/ D 4=0.99   [condition 3]
 
         [0098]    Further, the divergent surface  1036  of the light exit surface  1032  has a diopter value of −1500, while the convergent surface  1037  has a diopter value of 100. Thus, based on the above conditions, the light exit surface  1032  of the optical lens  103  may direct a light beam emitting from the light-emitting diode chip  102  to travel in a direction along the optical axis  103  and to project to a light receiving plane  20  through light refraction caused by the divergent surface  1036  and the convergent surface  1037  so as to form a non-symmetric light shape  21  projected onto the light receiving plane  20 . The non-symmetric light shape  21  has a configuration that is roughly a rectangle or an ellipse. Preferably, the non-symmetric light shape  21  has an aspect ratio between 1.51 and 1.6 in order to satisfy the ratio of image information acquired by a camera. The term “aspect ratio” used herein refers to the ratio of a maximum cross-sectional dimension of the non-symmetric light shape with a maximum cross-sectional dimension perpendicular to the maximum cross-sectional dimension. 
         [0099]    Further referring to  FIGS. 5 a  and 5 b   , which are polar luminous intensity distribution diagrams of the light-emitting diode according to the third embodiment of the present invention, in combination with  FIG. 4 ,  FIG. 5 a    is a polar luminous intensity distribution diagram on a plane passing through the optical axis  1034  and extending in the X-axis direction. When the light exit surface  1032  of the optical lens  103  is a free-form surface, with the optical lens  103  satisfying conditions 1-3, the diopter value of the divergent surface  1036  being −1500, and the diopter value of the convergent surface  1037  being 100, the light-emitting diode chip  102  is preferably used to generate infrared light having a wavelength between 830 and 870 nm with a peak value being 850 nm and a light distribution pattern being a bat-wing contour with a half-power (Full width at half maximum, FWHM) angle (which is a light angle that light intensive value is half of the intensive value of the axis direction) between 40 and 160 degrees, preferably 130 degrees. It can be known from the diagram that luminous intensity is not reducing from a central normal vector (0°) toward the peripheral edge and is in fact exhibited as being increase of illumination in the ranges of 0° to 50 and 0° to −50°. The maximum value of luminous intensity (Batwing peak) that the light-emitting diode  10   c  generates is at a location between around 40° and 60°, an optimum value being at 50°, the luminous intensity of the normal vector being 75% of the maximum luminous intensity, to thereby provide the best design of homogeneity.  FIG. 5 b    is the polar luminous intensity distribution diagram on a plane passing through the optical axis  1034  and orthogonal and perpendicular to the X-axis direction. The light exit surface  1032  of the optical lens  103  is a free-form surface, and the light-emitting diode chip  102  is preferably used to generate infrared light having a wavelength between 830 and 870 nm with a peak value being 850 nm, and showing a light shape in a light concentration form, with a half-power view angle between 30 and 100 degrees, preferably 85 degrees, but not limited thereto. Thus, the superimposition of the light shapes of X-axis and Y-axis helps improve homogeneity of luminous distribution. The light exit surface  1032  of the present invention, through the above described optical design, allows the light-emitting diode  102  to generate a non-symmetric light shape  21  having more homogeneous distribution. The light shape  21  has a configuration that is approximately a rectangle or an ellipse and the non-symmetric light shape  21  has an aspect ratio that is around 1.53, falling within the range discussed above. 
         [0100]    Further referring to  FIGS. 6 a  and 6 b   , an illuminance pattern of the light exit surface and a light exit ray of the third embodiment of the present invention is shown. As shown in the drawing, when the light exit surface  1032  of the optical lens  103  satisfies all the conditions and diopter values (the drawing shows the divergent surface  1036  has a diopter value of −1500, while the convergent surface  1037  has a diopter value of 100), a non-symmetric light shape  21  having homogeneity of 60% may be generated and the non-symmetric light shape  21  has a configuration that is roughly a rectangle. 
         [0101]    In the detail in contrast with the prior art, an example as  FIG. 16 a   , if a rectangular light shape of the embodiment needs to be shown, the rectangular opening needs to be deposed on the lens mechanism of the camera device so as to the photographed image is trimmed by the rectangular opening. That is, the horizontal axis and the vertical axis of  FIG. 16 a    are separately trimmed at the position, ±5.8 and ±4.7. The method not only loses more light energy, but also decreases coverage; therefore, the image of the photographed object is trimmed by the rectangular opening, which causes the distortion of the parts of image. 
       Fourth Embodiment 
       [0102]    Referring to  FIG. 7 , a schematic view is provided to show a light-emitting diode according to a fourth preferred embodiment of the present invention. The instant embodiment is applicable to an outdoor security surveillance system. Additional reference being had to  FIGS. 3 a -3 c   , the instant embodiment is different from the third embodiment in that the optical lens  30  of the instant embodiment has a light exit surface  1032  that is an aspheric surface, wherein D1 is approximately 3.0 mm, D2 is approximately 3.0 mm, D3 is approximately 2.2 mm, D4 is approximately 2.5 mm, and L1=L2=0.508 mm. Inserting these data into the conditions provided above in association with  FIGS. 3 a -3 c    provides the following conditions: 
         [0000]        D 1/ D 2=1   [condition 1]
 
         [0000]        L 1/ D 1=0.1693;  L 2/ D 2=0.1693   [condition 2]
 
         [0000]        D 3/ D 4=0.99   [condition 3]
 
         [0103]    Further, the aspheric surface is represented in equation 1 as follows: 
         [0000]    
       
         
           
             z 
             = 
             
               
                 
                   cr 
                   2 
                 
                 
                   1 
                   + 
                   
                     
                       1 
                       - 
                       
                         
                           ( 
                           
                             1 
                             + 
                             k 
                           
                           ) 
                         
                          
                         
                           c 
                           2 
                         
                          
                         
                           r 
                           2 
                         
                       
                     
                   
                 
               
               + 
               
                 
                   ∑ 
                   
                     t 
                     = 
                     1 
                   
                   n 
                 
                  
                 
                   
                     a 
                     t 
                   
                    
                   
                     a 
                     
                       2 
                        
                       t 
                     
                   
                 
               
             
           
         
       
     
         [0104]    where c denotes curvature, r indicates radius of curvature of an apex, and k indicate conic constant, and c=1/r and k&lt;0. 
         [0105]    In the instant embodiment, data are listed in the following Table 1, wherein the radius of curvature of apex (r), the conic constant (k), and aspheric coefficients of Nth orders (A4, A6, A8, A10, A12, A14, A16) are provided. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
             
               
                   
                 r 
                 9.03 
               
               
                   
                 k 
                 −0.522 
               
               
                   
                 A 4   
                 −1.872 × 10 −4   
               
               
                   
                 A 6   
                  5.099 × 10 −5   
               
               
                   
                 A 8   
                 −7.519 × 10 −6   
               
               
                   
                 A 10   
                  6.093 × 10 −7   
               
               
                   
                 A 12   
                 −2.766 × 10 −8   
               
               
                   
                 A 14   
                  6.591 × 10 −10   
               
               
                   
                 A 16   
                     −6.416 × 10 −12   
               
               
                   
                   
               
             
          
         
       
     
         [0106]    Further, the divergent surface  1036  of the light exit surface  1032  has a diopter value of −500 and the convergent surface  1037  has a diopter value of 25. Thus, when the optical lens  103  satisfies the above conditions and Table 1, the light exit surface  1032  of the optical lens  103  may direct a light beam emitting from the light-emitting diode chip  102  to travel in a direction along the optical axis  1034  and to project to a light receiving plane  20  through light refraction caused by the divergent surface  1036  and the convergent surface  1037  so as to form a non-symmetric light shape  21 . The non-symmetric light shape  21  has a configuration that is roughly a rectangle or an ellipse. Preferably, the non-symmetric light shape  21  has an aspect ratio between 1.51 and 1.6 in order to satisfy the ratio of image information acquired by a camera device. The term “aspect ratio” used herein refers to the ratio of a maximum cross-sectional dimension of the non-symmetric light shape with a maximum cross-sectional dimension perpendicular to the maximum cross-sectional dimension. 
         [0107]    Further referring to  FIGS. 8 a  and 8 b   , which are polar luminous intensity distribution diagrams of the light-emitting diode according to the fourth embodiment of the present invention, in combination with  FIG. 7 ,  FIG. 8 a    is a polar luminous intensity distribution diagram on a plane passing through the optical axis and extending in the X-axis direction. When the optical lens  103  satisfies conditions 1-3 and the light exit surface  1032  is an aspheric surface having the data listed in Table 1, a half-power view angle (which is a light angle that light intensive value is half of the intensive value of the axis direction) of the light-emitting diode chip  102  is around 47 degrees, but not limited thereto.  FIG. 8 b    is the polar luminous intensity distribution diagram on a plane passing through the optical axis  1034  and orthogonal and perpendicular to the X-axis direction. When the optical lens  103  satisfies conditions 1-3 and the light exit surface  1032  is an aspheric surface having the data listed in Table 1, a half-power view angle of the light-emitting diode chip  102  is around 31 degrees, but not limited thereto. Thus, the superimposition of the light shapes of X-axis and Y-axis helps improve homogeneity of luminous distribution. The above described design of the optical lens allows the light-emitting diode  102  to generate a non-symmetric light shape  21  having more homogeneous distribution. The light shape  21  has a configuration that is approximately a rectangle or an ellipse and the non-symmetric light shape  21  has an aspect ratio that is around 1.51, falling within the range discussed above. 
         [0108]    Further referring to  FIGS. 9 a  and 9 b   , an illuminance pattern of the light exit surface and a light exit ray of the fourth embodiment of the present invention is shown. As shown in the drawing, when the light exit surface  1032  of the optical lens  103  satisfies all the conditions and diopter values (the drawing shows the divergent surface  1036  has a diopter value of −500, while the convergent surface  1037  has a diopter value of 25), a non-symmetric light shape  21  having homogeneity of 60% may be generated and the non-symmetric light shape  21  has a configuration that is roughly a rectangle. 
         [0109]    In the detail in contrast with the prior art, an example as  FIG. 16 a   , if a rectangular light shape of the embodiment needs to be shown, the rectangle open needs to be deposed on the lens mechanism of the camera device so as to the photographed image is trimmed by the rectangle open. That is, the horizontal axle and the vertical axle of  FIG. 16 a    are separately trimmed at the position, ±4.2 and ±3.2. The method not only loses more light energy, but also decreases coverage; therefore, the image of the photographed object is trimmed by the rectangle open, which causes the distortion of the parts of image. 
         [0110]    Referring to  FIG. 10 , which is a schematic planar view illustrating a surveillance camera device according to the first embodiment of the present invention, the surveillance camera device  1  of the instant embodiment comprises at least one light-emitting diode  10   a , a casing  11 , and an image capturing element  12 . The casing  11  receives electronic circuit modules (not shown), such as an image sensor and a circuit board, mounted therein. The image capturing element  12  can be for example a fisheye lens. The image capturing element  12  is arranged in the casing  11  and partly projects out of the casing  11  to capture images. In the instant embodiment, the number of light-emitting diodes  10   a  being four is taken as an example, and the light-emitting diodes  10   a  are arranged on the casing  11  to circumferentially enclose the image capturing element  12  therein. Preferably, the light-emitting diodes  10   a  are arranged on the casing  11  in an angularly equally spaced manner to surround around the image capturing element  12 , but not limited thereto. In other embodiments, the number of the lighting module  10   a  that generates a non-symmetric light shape can be just one and located at one side of the image capturing element  12 . 
         [0111]    Referring to  FIG. 11 , which is a schematic side-elevational view illustrating the surveillance camera device of  FIG. 10  mounted to a ceiling. Reference being also had to  FIG. 1 , as shown in the drawings, when the surveillance camera device  1  is mounted to the ceiling  6 , with the image capturing element  12  being a fisheye lens, the image capturing element  12  may capture an image covering the ceiling  6  and the space under the ceiling  6 , and the light-emitting diode  10   a  may directly generate a non-symmetric light shape  21  required by the imaging system arranged inside the surveillance camera device  1  so as to increase coverage and reduce dark zones of image information. Compared to the prior art, the surveillance camera device  1  of the present invention does not require multiple optical elements to carry out refraction and reflection of secondary optics, thereby effectively reducing the overall size of the security surveillance system and helping achieve thinning of the system. Further, the optical energy of the non-symmetric light shape  21  is increased by 10%˜20% as compared to the optical energy of the conventionally used secondary optics. In other words, optical loss can be lower than the secondary optics by 10%˜20%, so as to improve utilization performance and homogeneity of the light source, achieving an effect of lowering down overall power consumption of the surveillance camera device  1  and also achieving reduction of distortion resulting from image compression and conversion. 
         [0112]    Further referring to  FIG. 13 , which shows an imaging result of a conventional surveillance camera device, as shown in the drawing, the prior art light shape is a circular-symmetry light shape so that the light intensity at a central portion is far greater than that of a peripheral portion, and thus, the peripheral zone of image information is completely a dark zone. Referring to  FIG. 12 , which shows an imaging result of a surveillance camera device according to the third embodiment of the present invention, with additional reference to  FIG. 4 , as shown in the drawing, the non-symmetric light shape  21  generated by the light-emitting diode  10   c  according to the present invention provides high homogeneity and illumination so that when used in a surveillance camera device of a security surveillance system, it can help improve coverage and reduce dark zone of the image information and does not requires multiple optical elements for reflection and refraction for secondary optics thereby increasing optical energy and further reducing the overall size of the security surveillance system. 
         [0113]    In summary, the light-emitting diode according to the present invention and the surveillance camera device using the light-emitting diode are applicable to a security surveillance system, wherein the light-emitting diode adopts primary optic design to allow for direct projection of non-symmetric light shape for matching an imaging system of the surveillance camera device, without the need of additional optical elements for multiple times of reflection for secondary optics thereby effectively improving utilization performance of the light source, reducing power consumption of the surveillance camera device, and also simplifying parts design of the security surveillance system to reduce overall size thereof. 
         [0114]    Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.