Patent Publication Number: US-2015069427-A1

Title: Omnidirectional lighting unit and illumination device and method for manufacturing omnidirectional lighting unit

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of Taiwan Patent Application No. 102132147, filed on Sep. 6, 2013, the entirety of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lighting unit and a lighting device using the lighting unit and a manufacturing method of the lighting unit, and more particularly to an omnidirectional lighting unit and a lighting device using the omnidirectional light unit and a manufacturing method of the omnidirectional lighting unit. 
     2. Description of the Related Art 
     With the development of lighting technology, varied new lighting elements are available. For example, LED (light-emitting diodes), halogen lamps and laser diodes are new lighting elements. 
     In general, the LED can be used in various types of lamp structures, such as the light bulb or the tubular lamp to provide illumination. The light emitted by the LED is radiated outwardly and passing through the cover of the light bulb or the tubular lamp to generate light on the front side direction thereof. Since the light emitting angle of the LED is less than 180 degrees, the light emitting angle of the LED light source is not satisfactory as compared with a conventional incandescent light source. 
     Consequently, the conventional LED needs to be further improved in terms of light emitting angle and luminous uniformity. 
     BRIEF SUMMARY OF THE INVENTION 
     One objective of the present invention is to provide a lighting unit with at least one light-emitting chip that is packaged by a spherical package member so as to provide an omnidirectional illumination. 
     According to some embodiments of the disclosure, the omnidirectional lighting unit includes a light-emitting chip, a spherical package member, a diffusion layer, and two conductive structures. The light-emitting chip has a positive electrode and a negative electrode. The spherical package member encapsulates the light-emitting chip, and the diffusion layer covers an outer surface of the spherical package member. The two conductive structures are electrically connected to the positive and negative electrodes, respectively. Each of the two conductive structures outwardly penetrates through the spherical package member and the diffusion layer, and a portion of each conductive structure is exposed to the exterior of the diffusion layer. 
     In some embodiments, each of the two conductive structures includes a conducting wire and a conductive terminal connected to the conducting wire. The conducting wires are electrically connected to the light-emitting chip. The conductive terminals outwardly penetrate through the package member and the diffusion layer, and a portion of each conductive terminal is exposed to the exterior of the diffusion layer. 
     In some embodiments, the two conductive structures are conducting wires. Alternatively, each of the conductive structures includes a conducting wire and a conductive terminal. 
     In some embodiments, the lighting unit further includes a wavelength conversion layer covering the outer surface of the diffusion layer. The diffusion layer includes light diffusion particles. The light diffusion particles are selected from a group consisting of silicon dioxide and titanium dioxide. 
     In some embodiments, the lighting unit further includes a protection layer covering the outer surface of the wavelength conversion layer. The protection layer includes at least two regions, each with a refractive index that is different from the other. The material of the protection layer is selected from a group consisting of epoxy resin, silicon resin, and acrylic resin. 
     In some embodiments, the light-emitting chip is an LED chip. In addition, the material of the spherical package member is selected from a group consisting of epoxy resin, silicon resin, and acrylic resin. 
     Another objective of the present invention is to provide a lighting device using any lighting unit in any of the embodiments mentioned above. The light unit includes N omnidirectional lighting units, where N is a natural number greater than or equal to 2. The light unit further includes N-1 connector(s) respectively between the omnidirectional lighting units and electrically connected to two of the omnidirectional lighting units neighboring to thereof. 
     Still another objective of the present invention is to provide a method to manufacture an omnidirectional lighting unit. According to some embodiments of the invention, the method to manufacture the omnidirectional lighting unit includes providing a light-emitting chip with a positive electrode and a negative electrode. The method also includes forming two conductive structures on the light-emitting chip. The two conductive structures are respectively electrically connected to the positive electrode and the negative electrode. The method further includes forming a first semi-spherical package member to encapsulate the upper surface of the light-emitting chip and a portion of the upper surface of the two conductive structures. In addition, the method includes forming a second semi-spherical package member to encapsulate the lower surface of the light-emitting chip and a portion of the lower surface of the two conductive structures so as to cooperatively form a spherical package member with the first semi-spherical package member. 
     Specifically, the operation of forming the first semi-spherical package member and the second semi-spherical package member includes providing a carrier to support the light-emitting chip; providing a first mold arranged on the carrier, wherein the first mold has a first mold cavity which covers the upper surface of the light-emitting chip and a portion of the upper surface of each conductive structure therein; injecting a first encapsulant material into the first mold cavity; removing the carrier; providing a second mold, wherein the second mold has a second mold cavity which covers the lower surface of the light-emitting chip and a portion of the lower surface of each conductive structure therein; injecting a second encapsulant material into the second mold cavity; curing the first encapsulant material and the second encapsulant material; and removing the first mold and the second mold to complete the first and second semi-spherical package members. 
     In some embodiments, the method further includes forming a diffusion layer to cover the outer surface of the spherical package member, forming a wavelength conversion layer to cover the outer surface of the diffusion layer, and forming a protection layer to cover the outer surface of the wavelength conversion layer. 
     In some embodiments, the two conductive structures are conducting wires. Alternatively, each of the conductive structures includes a conducting wire and a conductive terminal. 
     The light-emitting chip is surrounded by a spherical package member cooperatively formed by two semi-spherical package members. The light-emitting chip is not supported by a substrate or encapsulated by a package member that blocks light passing therethrough. Therefore, light emitted from the light-emitting chip is able to be radiated omnidirectionally. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings. 
         FIG. 1  shows a cross-sectional view of an omnidirectional lighting unit, in accordance with some embodiments. 
         FIG. 2  shows a cross-sectional view of an omnidirectional lighting unit, in accordance with some embodiments. 
         FIG. 3  shows a schematic view of a lighting device, in accordance with some embodiments. 
         FIGS. 4A-4H  show a method for manufacturing an omnidirectional lighting unit, in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
     Referring to  FIG. 1 , an omnidirectional lighting unit  100  includes a number of light-emitting chips, such as light-emitting chips  110 ,  120 , and  130 , a number of conductive structures, such as conductive structures  140   a - 140   f , and a package member  150 , in accordance with some embodiments. 
     The light-emitting chips  110 ,  120 , and  130  are located on the same plane. The light-emitting chips  110 ,  120 , and  130  are separated by a distance and not connected to each other to prevent light emitted from the neighboring light-emitting chips being absorbed by the others. However, the disclosure should not be limited thereto. In some embodiments, the light-emitting chips  110 ,  120 , and  130  are spaced at different distances. In some other embodiments, the number of light-emitting chips is varied according to demand. 
     In some embodiments, the light-emitting chips  110 ,  120 , and  130  are LED chips (Light Emitting Diode chips) which emit light with different wavelengths. For example, the light-emitting chip  110  emits blue light, the light-emitting chip  120  emits red light, and the light-emitting chip  130  emits green light. However, the disclosure should not be limited thereto. In some embodiments, all of the light-emitting chips  110 ,  120 , and  130  emit light with the same wavelength. 
     In some embodiments, each of the light-emitting chips  110 ,  120 , and  130  has a positive electrode  111  and a negative electrode  112 . For example, the light-emitting chip  110  has a positive electrode  111  and a negative electrode  112  formed on a single surface of the light-emitting chip  110 . Each of the conductive structures  140   a - 140   f  is a conducting wire (e.g., gold line). The conductive structure  140   a  and the conductive structure  140   b  are respectively electrically connected to the positive electrode  111  and the negative electrode  112  of the light-emitting chip  110 . The conductive structure  140   c  and the conductive structure  140   d  are respectively electrically connected to a positive electrode and a negative electrode of the light-emitting chip  120 . In addition, the conductive structure  140   e  and the conductive structure  140   f  are respectively electrically connected to a positive electrode and a negative electrode of the light-emitting chip  130 . In some embodiments, each negative electrode and each positive electrode of the light-emitting chips  110 ,  120 , and  130  are not only connected to a single conductive structure but connected to two or more conductive structures. In some other embodiments, each single conductive structure includes two conductive wires commonly connected to one positive electrode or one negative electrode of the light-emitting chips  110 ,  120 , and  130 . 
     The shape of the package member  150  is spherical. The package member  150  encapsulates the light-emitting chips  110 ,  120 , and  130  and a portion of the conductive structures  140   a - 140   f . The package member  150  is transparent. The material of the package member  150  is selected from a group consisting of epoxy resin, silicon resin, and acrylic resin. 
     In some embodiments, the omnidirectional lighting unit  100  further includes a diffusion layer  160 . The diffusion layer  160  for diffusing light is configured to increase the uniformity of light emitted from the light-emitting chips  110 ,  120 , and  130 . As shown in  FIG. 1 , the diffusion layer  160  includes diffusion particles  161  dispersed in the diffusion layer  160 . The diffusion particles  161  are selected from a group consisting of silver, resin, silicon (e.g., silicon dioxide and titanium dioxide), and other white compounds for scattering and mixing lights. Red light, blue light, and green light are mixed to produce white light in the diffusion layer  160  after hitting the diffusion particles  161 . Therefore, a light intensity reduction due to shielding effect is restrained. 
     In some embodiments, the omnidirectional lighting unit  100  further includes a wavelength conversion layer  170  covering the outer surface of the diffusion layer  160  by suitable means, such as coating. The wavelength conversion layer  170  includes wavelength conversion material  171 , such as a phosphor powder, quantum dot or organic emitting material, for converting a light emitted from each light-emitting chip  110 ,  120 , and  130  into a light with desirable wavelength. In some other embodiments, the wavelength conversion material  171 , including yellow phosphor (such as YAG), and a yellow light is obtained by a blue light emitted by the light-emitting chips  110 ,  120 , or  130  exciting yellow phosphor. 
     In some embodiments, the omnidirectional lighting unit  100  further includes a protection layer  180  covering the outer surface of the wavelength conversion layer  170  by suitable means, such as coating. The protection layer  180  is configured to protect the wavelength conversion layer  170 . The material of the protection layer  180  is selected from a group consisting of epoxy resin, silicon resin, and acrylic resin. As shown in  FIG. 1 , the protection layer  180  includes multiple regions  181  and  182 , each with a refractive index different from the other. With these arrangements, light passing through the protection layer  180  is affected by different refractive indexes, and a particular illumination purpose is achieved. 
     It is appreciated that the wavelength conversion layer  170  and the protection layer  180  are not an essential elements of the disclosure. In some embodiments, either the wavelength conversion layer  170  or the protection layer  180  is omitted. In some other embodiments, the omnidirectional lighting unit  100  includes two different wavelength conversion layers  170  sequentially arranged, so as to create particular optical effect. 
     It should be noted that no matter whether the omnidirectional lighting unit  100  includes the diffusion layer  160 , the wavelength conversion layer  170 , and/or the protection layer  180 , the end portion of each of the conductive structures  140   a - 140   f  is not completely covered by the diffusion layer  160 , the wavelength conversion layer  170 , and/or the protection layer  180 . Each of the conductive structures  140   a - 140   f  outwardly penetrates through the diffusion layer  160 , the wavelength conversion layer  170 , and/or the protection layer  180 . The end portion of each of the conductive structures  140   a - 140   f  is located at the outermost portion of the omnidirectional lighting unit  100  and is exposed to the exterior of the protection layer  180 . 
       FIG. 2  shows a cross-sectional view of an omnidirectional lighting unit  100 ′ in accordance with some embodiments. Since elements similar to those of the omnidirectional lighting unit  100  shown in  FIG. 1  are provided with the same reference numbers, the features thereof are not reiterated in the interest of brevity. In the embodiments, the conductive structures  140   a - 140   f  of the omnidirectional lighting unit  100  is replaced by conductive structures  190   a - 190   f . Each of the conductive structures  190   a - 190   f  includes a conductive wire (e.g., gold wire) and a conductive terminal connected to the conductive wire. The conductive wires are electrically connected to the light-emitting chips and encapsulated by the package member  150 . The conductive terminals outwardly penetrate through the diffusion layer  160 , the wavelength conversion layer  170 , and the protection layer  180 . The end portion of each conductive terminal is the outermost portion of the omnidirectional lighting unit  100 ′ and is exposed to the exterior of the protection layer  180  for connecting an external circuit. 
     For example, in the embodiment, the conductive structure  190   a  includes a conductive wire  191   a  and a conductive terminal  192   a . The conductive wire  191   a  is electrically connected to the positive electrode  111  of the light-emitting chip  110  and encapsulated by the package member  150 . The conductive terminal  192   a  outwardly penetrates through the diffusion layer  160 , the wavelength conversion layer  170 , and the protection layer  180 . The end portion of the conductive terminal  192   a  is the outermost portion of the omnidirectional lighting unit  100 ′ and is exposed to the exterior of the protection layer  180 . Similarly, the conductive structure  190   b  includes a conductive wire  191   b  and a conductive terminal  192   b . The conductive wire  191   b  is electrically connected to the negative electrode  112  of the light-emitting chip  110  encapsulated by the package member  150 . The conductive terminal  192   b  outwardly penetrates through the diffusion layer  160 , the wavelength conversion layer  170 , and the protection layer  180 . The end portion of conductive terminal  192   b  is exposed to the exterior of the protection layer  180 . The conductive structures  190   c ,  190   d ,  190   e , and  190   f  are connected to the light-emitting chips  120  and  130  by a similar method. For brevity of the specification, the description about the connections of the conductive structures  190   c ,  190   d ,  190   e , and  190   f  to the light-emitting chips  120  and  130  are omitted. 
     In some embodiments, since the stiffness of the conductive structures  190   a - f  is higher than that of the wires, after the package process of the omnidirectional lighting unit  100 ′, the conductive structures  190   a - 190   f  facilitate the electrical connection of the omnidirectional lighting unit  100 ′ to an external circuit. Therefore, the stability of the omnidirectional lighting unit  100 ′ is enhanced. 
       FIG. 3  shows a schematic view of a lighting device  300  using the omnidirectional lighting unit  100 ′ in accordance with some embodiments. The lighting device  300  includes a number of omnidirectional lighting units  100 ′ and a number of electrical connectors  310 . In some embodiments, each electrical connector  310  includes a number of receptacles  311   a - 311   f . The receptacle  311   a  is electrically connected to the receptacle  311   b . The receptacle  311   c  is electrically connected to the receptacle  311   d . The receptacle  311   e  is electrically connected to the receptacle  311   f . Each of the receptacles  311   a - 311   f  corresponds to one of the conductive terminals  192   a - 192   f.    
     To electrically connect two omnidirectional lighting units  100 ′, the lighting device  300  is placed between the two omnidirectional lighting units  100 ′. The conductive terminals  192   a ,  192   c , and  192   e  of one of the two omnidirectional lighting units  100 ′ are respectively inserted into the receptacles  311   a ,  311   c , and  311   e , and the conductive terminals  192   b ,  192   d , and  192   f  of the other omnidirectional lighting units  100 ′ are respectively inserted into the receptacles  311   b ,  311   d , and  311   f . In some other embodiments, the conductive terminals  192   a - 192   f  of the omnidirectional lighting units  100 ′ are electrically connected to a power source rather than another omnidirectional lighting unit  100 ′. 
     Referring to  FIGS. 4A-4H , the method for packaging the light-emitting chips  110 ,  120 , and  130  and the conductive structures  140   a - 140   f  ( FIG. 1 ) by the package member  150  (FIG.) is described hereinafter, in accordance with some embodiments. It should be noted that, in some embodiments, since the method for packaging the conductive structures  140   a - 140   f  is similar to the method for encapsulating the conductive structures  190   a - 190   f . For brevity, only the method for encapsulating the conductive structures  190   a - 190   f  is described in the following descriptions. 
     As shown in  FIG. 4A , a carrier  210  is provided, and the light-emitting chips  110 ,  120 , and  130  and the conductive members  190   a - 190   f  are supported by the carrier  210 , wherein the positive electrode and the negative electrode of the light-emitting chips  110 ,  120 , and  130  are electrically connected to the conductive members  190   a - 190   f . As shown in  FIG. 4B  (the conductive structures  190   c - 190   f  are not shown in  FIG. 4B ), the light-emitting chips  110 ,  120 , and  130  are mounted on the carrier  210  via the bottom surfaces  114 ,  124 , and  134  thereof, and the conductive structures  190   a  and  190   b  are connected to the carrier  210  via the bottom surfaces  1922   a  and  1922   b  thereof. 
     Afterwards, as shown in  FIG. 4C  (the conductive structures  190   c - 190   f  are not shown in  FIG. 4C ), a first mold  220  is provided on the carrier  210 . The first mold  220  has a first mold cavity  221 . The upper surfaces  113 ,  123 , and  133  of the light-emitting chips  110 ,  120 , and  130  and the upper surface  1921   a  and  1921   b  of the conductive structures  192   a  and  192   b  are covered by the first mold cavity  221 . Afterwards, as shown in  FIG. 4D  (the conductive structures  190   c - 190   f  are not shown in  FIG. 4D ), a first encapsulant material  230  is injected into the first mold cavity  221 . Therefore, the light-emitting chips  110 ,  120 , and  130 , the conductive wires  191   a  and  191   b , and a portion of each of the conductive structures  192   a  and  192   b  are packaged by the first encapsulant material  230 . 
     Referring to  FIG. 4E  (the conductive structures  190   c - 190   f  are not shown in  FIG. 4E ), after the injection of the first encapsulant material  230 , the carrier  210  is removed from the light-emitting chips  110 ,  120 , and  130  and the conductive structures  192   a  and  192   b . At this time, the bottom surfaces  114 ,  124 , and  134  of the light-emitting chips  110 ,  120 , and  130  and the bottom surfaces  1922   a  and  1922   b  of the conductive structures  192   a  and  192   b  are exposed the exterior of the first encapsulant material  230 . 
     Afterwards, as shown in  FIG. 4F  (the conductive structures  190   c - 190   f  are not shown in  FIG. 4F ), a second mold  240  is provided on the first mold  210 . The second mold  240  has a second mold cavity  241 . The bottom surfaces  114 ,  124 , and  134  of the light-emitting chips  110 ,  120 , and  130  and the bottom surfaces  1922   a  and  1922   b  of the conductive structures  192   a  and  192   b  are covered by the second mold cavity  241 . Afterwards, as shown in  FIG. 4G  (the conductive structures  190   c - 190   f  are not shown in  FIG. 4G ), a second encapsulant material  250  is injected into the second mold cavity  241 . Therefore, the light-emitting chips  110 ,  120 , and  130 , the conductive wires  191   a  and  191   b , and a portion of each of the conductive structures  192   a  and  192   b  are packaged by the second encapsulant material  250 . 
     Afterwards, the first encapsulant material  230  and the second encapsulant material  250  are baked, so that the first encapsulant material  230  and the second encapsulant material  250  are cured. After the baking process, the first mold  220  and the second mold  240  are removed. The manufacturing process of the first semi-spherical package member  230  and the second semi-spherical package member  250  is completed. At this time, a spherical package member is cooperatively formed by the first semi-spherical package member  230  and the second semi-spherical package member  250 , as shown in  FIG. 4H . 
     It should be noted that the light-emitting chips  110 ,  120 , and  130 , the conductive wires  191   a  and  191   b , and a portion of each of the conductive structures  192   a  and  192   b  are entirely packaged by the spherical package member. Additionally, the other portion of each of the conductive structures  192   a  and  192   b  are exposed the exterior of the first semi-spherical package member  230  and the second semi-spherical package member  250  for electric connection to an external circuit. 
     The omnidirectional lighting unit of the disclosure includes a spherical package member for packaging the light-emitting chips. Light from the light-emitting chips is radiated via the entire outer surface of the spherical package member. Therefore, the light angle and the light uniformity of the omnidirectional lighting unit are better than that of the conventional light emitting package structure. 
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.