Patent Publication Number: US-2012032216-A1

Title: Light Emitting Diode Package Structure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Taiwan Patent Application No. 099126119, entitled “Light Emitting Diode Package Structure”, filed on Aug. 5, 2010, which is herein incorporated in its entirety by reference. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a light emitting diode (LED) package structure. More particularly, the present disclosure relates to an LED package structure with reduced stray light. 
     2. Description of Related Art 
     LEDs generally offer a number of advantageous characteristics such as fast response, compact size, low power consumption, low environmental pollution, high reliability, ease of mass production, etc. As a result LEDs are employed in a wide variety of applications including vehicle headlights, illumination fixtures, bulletin boards, traffic signal lights, mobile phones, and so on. 
     In operation LED chips generate heat. In the even that such heat accumulates in the LED chip and is not removed in a timely fashion, such heat may result in reduced efficiency in light emission or even damage to the LED chip. Therefore, common designs of LED lighting fixtures usually provide relatively large space to accommodate heat dissipating components at the expense of providing less space to accommodate optical components. With the size of optical components constrained by a relatively small space, the optical components may not collimate all the light emitted by the LED chip, resulting in the LED chip appearing to be a large illumination area with more stray light. 
     SUMMARY 
     The present disclosure provides an LED package structure that has a small illumination area with less stray light. 
     In one aspect, an LED package structure may comprise a base, at least one LED chip, a blocking plate, and a transparent cover plate. The at least one LED chip is disposed on and electrically coupled to the base. The blocking plate is disposed on the base and surrounds the at least one LED chip. The blocking plate has an opening that exposes the at least one LED chip. The blocking plate comprises an opaque light-absorbing material. The transparent cover plate is disposed on the blocking plate and covers the opening of the blocking plate. 
     In one embodiment, the blocking plate has an inner sidewall and a first upper surface, and the at least one LED chip has a second upper surface and a side farthest from the inner sidewall of the blocking plate. The inner sidewall and the first upper surface of the blocking plate form a first vertex. The side and the second upper surface of the at least one LED chip form a second vertex. A straight line connecting the first vertex and the second vertex and the second upper surface form an included angle that is no greater than 30°. 
     In another embodiment, the blocking plate has an inner sidewall and the at least one LED chip has a side farthest from the inner sidewall of the blocking plate. An interval distance between the inner sidewall of the blocking plate and the side of the at least one LED chip farthest from the inner sidewall of the blocking plate is D. A height difference between the blocking plate and the at least one LED chip is T. A ratio of the height difference T to the interval distance D is no greater than tan 30°. 
     In another aspect, an LED package structure may comprise a carrier having a recess, at least one LED chip, and a cover plate. The at least one LED chip is received in the recess of the carrier and electrically coupled to the carrier. The cover plate is disposed on the carrier and covers the recess of the carrier. The cover plate has a transparent region and an opaque region surrounding the transparent region such that light generated by the at least one LED chip emits out of the transparent region. 
     In one embodiment, the opaque region has an inner sidewall and a first upper surface, and the at least one LED chip has a second upper surface and a side farthest from the inner sidewall of the opaque region. The inner sidewall and the first upper surface of the opaque region form a first vertex. The side and the second upper surface of the at least one LED chip form a second vertex. A straight line connecting the first vertex and the second vertex and the second upper surface form an included angle that is no greater than 20°. 
     In another embodiment, the opaque region has an inner sidewall, and the at least one LED chip has a side farthest from the inner sidewall of the opaque region. An interval distance between the inner sidewall of the opaque region and the side of the at least one LED chip farthest from the inner sidewall of the opaque region is D. A height difference between the cover plate and the at least one LED chip is T. A ratio of the height difference T to the interval distance D is no greater than tan 20°. 
     In another embodiment, the cover plate comprises a transparent plate and an opaque structure. The transparent plate is disposed on the carrier and covers the recess of the carrier. The opaque structure is disposed on the transparent plate and within the opaque region of the cover plate. The opaque structure has an opening exposing a portion of the transparent plate that is within the transparent region of the cover plate. 
     In still another embodiment, the cover plate comprises a transparent plate and an opaque structure. The transparent plate is disposed on the carrier and covers the recess of the carrier. The opaque structure is disposed between the transparent plate and the carrier, and is also disposed within the opaque region. The opaque structure has an opening corresponding to the recess of the carrier and a portion of the transparent plate that is within the transparent region of the cover plate. 
     In yet another embodiment, the opaque region covers at least partially a sidewall of the carrier. 
     In a further embodiment, the carrier comprises a base and a blocking plate. The at least one LED chip is disposed on the base and electrically coupled to the base. The blocking plate is disposed on the base and has an opening exposing the at least one LED chip. The opening of the blocking plate and the base form the recess. The blocking plate comprises an opaque light-absorbing material. The at least one LED chip is disposed in the opening. The cover plate is disposed on the blocking plate and covers the opening of the blocking plate. 
     In a further aspect, an LED package structure may comprise a carrier having a recess, at least one LED chip, a transparent cover plate, and a light-absorbing layer. The at least one LED chip is received in the recess of the carrier and electrically coupled to the carrier. The transparent cover plate is disposed on the carrier and covers the recess of the carrier. The light-absorbing layer is disposed on the transparent cover plate and has an opening such that at least a portion of light generated by the at least one LED chip emits through the transparent cover plate and the opening of the light-absorbing layer. 
     In one embodiment, the light-absorbing layer has an inner sidewall and a first upper surface, and the at least one LED chip has a second upper surface and a side farthest from the inner sidewall of the light-absorbing layer. The inner sidewall and the first upper surface of the light-absorbing layer form a first vertex. The side and the second upper surface of the at least one LED chip form a second vertex. A straight line connecting the first vertex and the second vertex and the second upper surface form an included angle that is no greater than 30°. 
     In another embodiment, the light-absorbing layer has an inner sidewall, and the at least one LED chip has a side farthest from the inner sidewall of the light-absorbing layer. An interval distance between the inner sidewall of the light-absorbing layer and the side of the at least one LED chip farthest from the inner sidewall of the light-absorbing layer is D. A height difference between the transparent cover plate and the at least one LED chip is T. A ratio of the height difference T to the interval distance D is no greater than tan 30°. 
     In one embodiment, the light-absorbing layer has an inner sidewall and a first upper surface, and the at least one LED chip has a second upper surface and a side farthest from the inner sidewall of the light-absorbing layer. The inner sidewall and the first upper surface of the light-absorbing layer form a first vertex. The side and the second upper surface of the at least one LED chip form a second vertex. A straight line connecting the first vertex and the second vertex and the second upper surface form an included angle that is no greater than 20°. 
     In another embodiment, the light-absorbing layer has an inner sidewall, and the at least one LED chip has a side farthest from the inner sidewall of the light-absorbing layer. An interval distance between the inner sidewall of the light-absorbing layer and the side of the at least one LED chip farthest from the inner sidewall of the light-absorbing layer is D. A height difference between the transparent cover plate and the at least one LED chip is T. A ratio of the height difference T to the interval distance D is no greater than tan 20°. 
     In one embodiment, the light-absorbing layer has an inner sidewall and a first upper surface, and the at least one LED chip has a second upper surface and a side farthest from the inner sidewall of the light-absorbing layer. The inner sidewall and the first upper surface of the light-absorbing layer form a first vertex. The side and the second upper surface of the at least one LED chip form a second vertex. A straight line connecting the first vertex and the second vertex and the second upper surface form an included angle that is no greater than 18°. 
     In another embodiment, the light-absorbing layer has an inner sidewall, and the at least one LED chip has a side farthest from the inner sidewall of the light-absorbing layer. An interval distance between the inner sidewall of the light-absorbing layer and the side of the at least one LED chip farthest from the inner sidewall of the light-absorbing layer is D. A height difference between the transparent cover plate and the at least one LED chip is T. A ratio of the height difference T to the interval distance D is no greater than tan 18°. 
     In one embodiment, the light-absorbing layer covers at least partially a sidewall of the transparent cover plate. 
     In one embodiment, the light-absorbing layer covers at least partially a sidewall of the transparent cover plate and a sidewall of the carrier. 
     In one embodiment, the carrier comprises a base and a blocking plate. The at least one LED chip is disposed on the base and electrically coupled to the base. The blocking plate is disposed on the base and has an opening exposing the at least one LED chip. The opening of the blocking plate and the base form the recess. The blocking plate comprises an opaque light-absorbing material. The at least one LED chip is disposed in the opening. The transparent cover plate is disposed on the blocking plate and covers the opening of the blocking plate. 
     These and other features, aspects, and advantages of the present disclosure will be explained below with reference to the following figures. It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the present disclosure as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. 
         FIG. 1A  illustrates an LED package structure in accordance with an embodiment of the present disclosure. 
         FIG. 1B  illustrates a vertical view of the LED package structure of  FIG. 1A . 
         FIG. 1C  illustrates a cross-sectional view of the LED package structure of  FIG. 1B  along the line A-A. 
         FIG. 2A  illustrates a variation of the LED package structure of  FIG. 1A . 
         FIG. 2B  illustrates a vertical view of the LED package structure of  FIG. 2A . 
         FIG. 2C  illustrates a cross-sectional view of the LED package structure of  FIG. 2B  along the line A-A. 
         FIG. 3A  illustrates an LED package structure in accordance with another embodiment of the present disclosure. 
         FIG. 3B  illustrates a vertical view of the LED package structure of  FIG. 3A . 
         FIG. 3C  illustrates a cross-sectional view of the LED package structure of  FIG. 3B  along the line A-A. 
         FIG. 4A  illustrates a variation of the LED package structure of  FIG. 3A . 
         FIG. 4B  illustrates a vertical view of the LED package structure of  FIG. 4A . 
         FIG. 4C  illustrates a cross-sectional view of the LED package structure of  FIG. 4B  along the line A-A. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1A  illustrates an LED package structure in accordance with an embodiment of the present disclosure.  FIG. 1B  illustrates a vertical view of the LED package structure of  FIG. 1A .  FIG. 1C  illustrates a cross-sectional view of the LED package structure of  FIG. 1B  along the line A-A. 
     Referring to  FIGS. 1A ,  1 B and  1 C, the LED package structure  100  comprises a carrier  110 , a plurality of LED chips  120 , and a transparent cover plate  130 . 
     The carrier  110  comprises a base  112  and a blocking plate  114 . The blocking plate  114  is disposed on the base  112  and has an opening  114   a  which exposes at least a portion of the base  112 . The material of the blocking plate  114  comprises a light-absorbing material that is opaque such as, for example, a black or dark ceramic material or light-absorbing layer. The material of the base  112  may be, for example, ceramic, glass, silicon or metal. In one embodiment, the base  112  and the blocking plate  114  may be a monolithic structure formed as one piece. 
     The plurality of LED chips  120  are flip chip bonded to, as well as electrically coupled to, the base  112 , and are located on a portion of the base  112  that is exposed by the opening  114   a  of the blocking plate  114 . The blocking plate  114  surrounds the plurality of LED chips  120  and, relative to an optical axis of the LED chips  120 , a primary surface of the blocking plate  114  may be perpendicular or otherwise angled. In one embodiment, as shown in  FIG. 1C  and using the right-most LED chip  120  as a representative of the other LED chips  120 , given a thickness of the blocking plate  114  being H 1 , a thickness of the right-most LED chip  120  being H 2 , a distance, or height difference, between a surface of the blocking plate  114  that faces away from the base  112  and a surface of the right-most LED chip  120  that faces away from the base  112  being T 1 , a width of the right-most LED chip  120  being W, and a distance between a side of the right-most LED chip  120  closest to the blocking plate  114  and a side of the blocking plate  114  closest to the right-most LED chip  120  being D 1 , then a relationship among these parameters can be expressed as T 1 /(W+D 1 )≦tan θ 1 . In particular, the angle θ 1  denotes the angle between the light ray L emitted by the LED chip  120  out of the opening  114  (i.e., θ 1  is the angle between the light ray L emitted from the left-most portion of the right-most LED chip  120  and the top surface of the right-most LED chip  120 , and θ 1  is also the angle between the light ray L emitted from the left-most portion of the right-most LED chip  120  and the top surface of the blocking plate  114 ). In one embodiment, T 1 /(W+D 1 )≦tan 30°. In another embodiment, T 1 /(W+D 1 )≦tan 20°. In an alternative embodiment and preferably, T 1 /(W+D 1 )≦tan 18°. The transparent cover plate  130  is disposed on the blocking plate  114 , located above the plurality of LED chips  120 , and covers the opening  114   a.  The material of the transparent cover plate  130  may comprise glass or any other suitable transparent material. 
     Given that the LED chips  120  are flip chip bonded to the base  112 , in one embodiment the opening  114   a  may be sized and shaped such that the inner sidewalls  114   b  of the opening  114   a  may be as close to the sides  122  of the LED chips  120  as possible. 
     Noticeably, by defining a height difference of between the blocking plate  114  and an LED chip  120  being T 1 , the width of the LED chip  120  being W, and an interval distance between one of the LED chips  120  and the blocking plate  114  being D 1 , the angle θ 1  at which the light ray L is emitted from the LED chip  120  out of the opening  114   a  can be derived. That is, through the equation T 1 /(W+D 1 )≦tan 30° (or tan 20° or tan 18°), the angle θ 1  can be determined to be 30° (or 20° or 18°). 
     In other words, the LED chip  120  has two opposing sides: a first side (e.g., the right side) and a second side (e.g., the left side) where the first side is closer to the blocking plate  114  (e.g., the inner sidewall on the right) than the second side. With a height difference (e.g., T 1 ) between the blocking plate  114  and the LED chip  120  and an interval distance (e.g., D 1 ) between the blocking pate  114  (e.g., the inner sidewall on the right) and the first side (e.g., the right side), a ratio of the height difference to the interval distance is no greater than a tangent function of 30 degrees, tan 30°. 
     In one embodiment, the blocking plate  114  has an inner sidewall (e.g., the inner sidewall on the right) and a first upper surface. The LED chip  120  has a second upper surface and a side (e.g., the left side) that is farthest from the inner sidewall of the blocking plate  114 . Between the inner sidewall and the first upper surface of the blocking plate  114  there is a first vertex (e.g., a corner vertex), and between the side and the second upper surface of the LED chip  120  there is a second vertex (e.g., a corner vertex). Between a straight line connecting the first vertex and the second vertex (e.g., the light ray L) and the second upper surface there is an included angle (e.g., the angle θ 1 ) that is no greater than 30°. 
     In another embodiment, the blocking plate  114  has an inner sidewall (e.g., the inner sidewall on the right), and the LED chip  120  has a side (e.g., the left side) that is farthest from the inner sidewall of the blocking plate  114 . Between the inner sidewall of the blocking plate  114  and the side of the LED chip  120  there is an interval distance (e.g., D 1 ), and between the blocking plate  114  and the LED chip  120  there is a height difference (e.g., T 1 ). A ratio of such height difference and interval distance is no greater than the tangent function of 30 degrees, tan 30°. 
     Moreover, with the inner sidewalls  114   b  of the opening  114   a  as close to the sides  122  of the LED chips  120  as possible according to one embodiment, the inner sidewalls  114   b  can be used to block large-angle stray light emitted from the sides  122  of the LED chips  120 . The blocking plate  114  can absorb a majority of incident light, attenuate the strength of reflection of the incident light, and reduce the probability of reflection of the incident light, thereby reducing the illumination area of the LED package structure  100  and lowering the effect of surface light source. Additionally, the height of the blocking plate  114  and the size of the opening  114   a  may be flexibly designed to adjust and control the light emitting field or pattern of the LED chips  120 . 
     Furthermore, with the inner sidewalls  114   b  of the opening  114   a  as close to the sides  122  of the LED chips  120  as possible according to one embodiment, the inner sidewalls  114   b  in turn limit the amount of area spreadable with phosphorus and thereby limit the illumination area of the LED package structure. 
       FIG. 2A  illustrates a variation of the LED package structure of  FIG. 1A .  FIG. 2B  illustrates a vertical view of the LED package structure of  FIG. 2A .  FIG. 2C  illustrates a cross-sectional view of the LED package structure of  FIG. 2B  along the line A-A. 
     Referring to  FIGS. 2A ,  2 B and  2 C, the LED package structure  200  in accordance with one embodiment is similar to the LED package structure  100  of  FIG. 1A  with the main difference being that the LED chips  120  of the LED package structure  200  are wire bonded to the base  112 . More specifically, the LED package structure  200  also comprises a plurality of conductive wires  210  that provide electrical conductive paths between the LED chips  120  and the base  112 . In one embodiment, the conductive wires  210  are gold wires. 
     In one embodiment, as it is necessary to reserve a portion of the space of the opening  114   a  for the purpose of wire bonding, a portion of the inner sidewalls  114   b  of the opening  114   a  can be as close to the sides  122  of the LED chips as possible. In one embodiment, the LED chips  120  and the direction of wire bonding are so arranged such that the portion of the inner sidewalls  114   b  of the opening  114   a  that can be as close to the sides  122  of the LED chips  120  as possible is maximized. 
     In one embodiment, the LED chips  120  are arranged in a row (or a line or an array), with multiple conductive wires  210  connected between respective outer sides of the LED chips  120  and conductive lines  112   b  of the base  112 . As such, two opposing inner sidewalls  114   b  of the opening  114   a  can be as close to the sides  122  of the LED chips  120  as possible. 
       FIG. 3A  illustrates an LED package structure in accordance with another embodiment of the present disclosure.  FIG. 3B  illustrates a vertical view of the LED package structure of  FIG. 3A .  FIG. 3C  illustrates a cross-sectional view of the LED package structure of  FIG. 3B  along the line A-A. 
     Referring to  FIGS. 3A ,  3 B and  3 C, the LED package structure  300  comprises a carrier  310 , a plurality of LED chips  320 , and a cover plate  330 . The carrier  310  has a recess  312 . More specifically, in one embodiment, the carrier  310  comprises a base  314  and a blocking plate  316 . The blocking plate  316  is disposed on the base  314  and has an opening  316   a  that exposes a partial surface  314   a  of the base  314 . The inner sidewalls  316   b  of the opening  316   a  and the partial surface  314   a  of the base  314  form the recess  312 . The base  314  and the blocking plate  316  are each made of an opaque material such as, for example, ceramic, silicon or metal. Additionally, the base  314  and the blocking plate  316  may be a monolithic structure formed as one piece. 
     The LED chips  320  are disposed in the recess  312  and electrically coupled to the carrier  310 . The cover plate  330  is disposed on the carrier  310 , located over the LED chips  320 , and covers the recess  312 . The cover plate  330  comprises a transparent region  332  and an opaque region  334  surrounding the transparent region  332 . The transparent region  332  is disposed above the LED chips  320 . Noticeably, in one embodiment, a ratio between the width W 1  of the transparent region  332  and the width W of the LED chips  320  represents a ratio between the width W 1  of the transparent region  332  and the width W of the LED chips  320  in the same cross section (e.g., the cross section along the line A-A in  FIG. 3B ). Additionally, if the cross section intersects more than one of the LED chips  320 , then the ratio is between the width W 1  of the transparent region  332  and the sum of the widths W of all the LED chips  320  that intersect the cross section. 
     In one embodiment, the cover plate  330  comprises a transparent plate  336  and an opaque structure  338 . The transparent plate  336  is disposed on the carrier  310 , located over the LED chips  320 , and covers the recess  312 . The opaque structure  338  is disposed on the transparent plate  336  and is within the opaque region  334 . The opaque structure  338  has an opening  338   a  that exposes a portion of the transparent plate  336  that is within the transparent region  332 . The opaque structure  338  may be, for example, a black ink layer or a light-absorbing layer. Relative to an optical axis of the LED chips  120 , a primary surface of the opaque structure  338  may be perpendicular or otherwise angled. Moreover, the opaque structure  338  may be disposed between the transparent plate  336  and the blocking plate  316 . The opaque structure  338  may be disposed between the transparent plate  336  and the carrier  310 , and may be within the opaque region  334 . The opaque structure  338  may have an opening that corresponds to the recess  312  and the portion of the transparent plate  336  that is within the transparent region  332 . 
     Referring to  FIG. 3C , in one embodiment, the opaque structure  338  has a thickness of H 3 , the LED chips  320  in general have a thickness of H 2 , and a surface of a side of the transparent plate  336  of the cover plate  330  facing away from the carrier  310  has a height of T 3  as measured from a surface of a side of the LED chips  320  facing away from the carrier  310 . A surface of a side of the opaque structure  338  of the cover plate  330  facing away from the carrier  310  has a height of T 2  as measured from a surface of a side of the LED chips  320  facing away from the carrier  310  (equal to the sum of T 3  and H 3 ). The LED chips  320  each has a width of W. A horizontal interval distance between a side surface of an LED chip  320  near the opaque region  334  and a side surface of the opaque region  334  near the LED chip  320  is D 2  (in other words, the horizontal interval distance between a side surface of an LED chip  320  near the opaque structure  338  and a side surface of the opaque structure  338  near the LED chip  320  is D 2 ). A relationship among these parameters can be expressed as T 2 /(W+D 2 )≦tan θ 2 ≦T 2 /W. In one embodiment, the value of D 2  may be 0. The angle θ 2  denotes the angle between the light ray L emitted by the LED chip  320  out of the opening  316   a  (i.e., θ 2  is the angle between the light ray L emitted from the left-most portion of the LED chip  320  and the top surface of the LED chip  320 , and θ 2  is also the angle between the light ray L emitted from the left-most portion of the LED chip  320  and the top surface of the opaque structure  338 ). In one embodiment, preferably the angle θ 2  is 30°. 
     By defining a height difference of between the cover plate  330  and an LED chip  320  being T 2 , the width of the LED chip  320  being W, and an interval distance between the LED chip  320  and the opaque region  334  being D 2  (or equivalently an interval distance between the LED chip  320  and the opaque structure  338  being D 2 ), the angle θ 2  at which the light ray L is emitted from the LED chip  320  out of the opening  316   a  can be derived. That is, through the equation T 2 /(W+D 2 )≦tan θ 2 , the angle θ 2  can be determined, for example, to be 20°. 
     In other words, the LED chip  320  has two opposing sides: a first side (e.g., the right side) and a second side (e.g., the left side) where the first side is closer to the opaque region  334  (e.g., the inner sidewall on the right) than the second side. With a height difference (e.g., T 2 ) between the cover plate  330  and the LED chip  320  and an interval distance (e.g., D 2 ) between the opaque region  334  (e.g., the inner sidewall on the right) and the first side (e.g., the right side), a ratio of the height difference to the interval distance is no greater than a tangent function of 20 degrees, tan 20°. 
     In one embodiment, the opaque region  334  has an inner sidewall (e.g., the inner sidewall on the right) and a first upper surface. The LED chip  320  has a second upper surface and a side (e.g., the left side) that is farthest from the inner sidewall of the opaque region  334 . Between the inner sidewall and the first upper surface of the opaque region  334  there is a first vertex (e.g., a corner vertex), and between the side and the second upper surface of the LED chip  320  there is a second vertex (e.g., a corner vertex). Between a straight line connecting the first vertex and the second vertex (e.g., the light ray L) and the second upper surface there is an included angle (e.g., the angle θ 2 ) that is no greater than 20°. 
     In another embodiment, the opaque region  334  has an inner sidewall (e.g., the inner sidewall on the right), and the LED chip  320  has a side (e.g., the left side) that is farthest from the inner sidewall of the opaque region  334 . Between the inner sidewall of the opaque region  334  and the side of the LED chip  320  there is an interval distance (e.g., D 2 ), and between the cover plate  330  and the LED chip  320  there is a height difference (e.g., T 2 ). A ratio of such height difference and interval distance is no greater than a tangent function of 20 degrees, tan 20°. 
     Noticeably, in one embodiment, the size of the transparent region  332  can be adjusted by adjusting the size of the opening  338   a  of the opaque structure  338  (width or area), so as to adjust the illumination area of the LED package structure  300 . Accordingly, stray light emitted from the side  322  of the LED chip  320  can be minimized by reducing the size of the opening  338   a  of the opaque structure  338 . The opaque structure  338  can absorb a majority of incident light, attenuate the strength of reflection of the incident light, and reduce the probability of reflection of the incident light, thereby reducing the light guide effect of the transparent plate  336  and lowering the effect of surface light source. Additionally, the height of the opaque region  334  and the size of the transparent region  332  may be flexibly designed to adjust and control the light emitting field or pattern of the LED chips  320 . 
       FIG. 4A  illustrates a variation of the LED package structure of  FIG. 3A .  FIG. 4B  illustrates a vertical view of the LED package structure of  FIG. 4A .  FIG. 4C  illustrates a cross-sectional view of the LED package structure of  FIG. 4B  along the line A-A. 
     Referring to  FIGS. 4A ,  4 B and  4 C, the LED package structure  400  in accordance with one embodiment is similar to the LED package structure  300  of  FIG. 3A  with the main difference being that the opaque structure  338  of the LED package structure  400  further includes an extension  338   b.  The extension  338   b  may cover at least partially the outer sidewalls  336   a  and  318  of the transparent plate  336  and the carrier  310 , respectively. The opaque structure  338  may be, for example, a metallic shell. The opaque structure  338  may be press fitted, glued or otherwise coupled to the transparent plate  336  and the carrier  310 . 
     Noticeably, when the material of the opaque structure  338  is a material with good reflectivity (e.g., a metallic material), then the light blocked by the opaque structure  338  (e.g., light emitted by the LED chips  320 ) may be reflected a plurality of times between an inner surface  338   c  of the opaque structure  338  and the carrier  310  before being emitted out of the opening  338   a.  As a result, the amount of light emitted from the LED package structure  400  is increased. In one embodiment, regardless of whether the opaque structure  338  is made of a reflective material, a reflective layer structure may be provided between the opaque structure  338  and the transparent plate  336  and between the opaque structure  338  and the carrier  310 . 
     In view of the above description, an LED package structure according to the present disclosure may include an opaque and light-absorbing blocking plate. Large-angle stray light emitted from the sides of the LED chips can be blocked by having the inner sidewalls of the opening of the blocking plate close to the sides of the LED chips. This reduces the illumination area of the LED package structure and lowers the effect of surface light source. 
     An LED package structure according to the present disclosure may further include a cover plate disposed on the carrier. The cover plate includes a transparent region and an opaque region surrounding the transparent region. The illumination area of the LED package structure can be reduced by reducing the size of the transparent region. Stray light emitted from the sides of the LED chips can also be reduced. As a result, the effect of surface light source is reduced accordingly. 
     Although some embodiments are disclosed above, they are not intended to limit the scope of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments of the present disclosure without departing from the scope or spirit of the present disclosure. In view of the foregoing, the scope of the present disclosure shall be defined by the following claims and their equivalents.