CN202111155U - LED package - Google Patents

Abstract

The utility model relates to LED packaging, including a plastic housing, an LED chip arranged in the housing and transition material for transforming at least some light emitted by the LED chip. The LED packaging emits packaging light, and the packaging light includes light coming from the transition material or combined light coming from the transition material and the LED chip. The LED packaging also includes a reflection area surrounding the LED chip and a contrast area out of the reflection area. The contrast area possesses colors forming contrast to the packaging light. In the utility model, good contrast among different pixels in the LED billboard and display is provided according to the LED packaging provided in the utility model, simultaneously, the luminous flux or brightness of the display perception is not reduced.

Description

LED package

technical field

The utility model relates to a light-emitting diode (LED) package and a display using the light-emitting diode package as its light source.

Background technique

Light emitting diodes (LEDs or LEDs) are solid-state devices that convert electrical energy into light, usually comprising one or more active layers of semiconductor material sandwiched between oppositely doped layers. When a bias voltage is applied across the aforementioned doped layers, holes and electrons are injected into the active layer where they recombine to generate light. Light is emitted from the active layer as well as all surfaces of the LED.

In the last decade or more, technological advances have resulted in LEDs with smaller footprints, increased emission efficiencies, and reduced costs. LEDs also have an extended operating life compared to other emitters. For example, the operating life of LEDs can exceed 50,000 hours, while the operating life of incandescent light bulbs is about 2,000 hours. LEDs can also be more robust and consume less energy than other light sources. For these and other reasons, LEDs are more popular and are now used in more and more traditional field applications of incandescent, fluorescent, halogen and other emitters.

In order to use LED chips in traditional applications, it is known to enclose the LED chips in packages to provide environmental and/or mechanical protection, color selection, light concentration, and the like. The LED package also includes electrical leads, contacts or traces for electrically connecting the LED package to an external circuit. In a typical two-lead LED package/component 10 shown in FIG. 1, a single LED chip 12 is mounted on a reflective cup 13 by solder bonding or conductive epoxy. One or more wire bonds 11 connect the ohmic contacts of the LED chip 12 to leads 15A and/or 15B, which may be attached to or integrated with the reflective cup 13 . The reflective cup 13 may be filled with an encapsulant material 16 and a wavelength converting material such as a phosphor may be included over the LED chip or in the encapsulant. The phosphor can absorb light emitted by the LED at a first wavelength and spontaneously emit light at a second wavelength. The entire assembly can then be encased in a transparent protective resin 14 which can be molded in the shape of a lens to guide or shape the light emitted from the LED chip 12 .

The conventional LED package 20 shown in FIG. 2 may be better suited for high power operation which can generate more heat. In LED package 20 , one or more LED chips 22 are mounted on a carrier, such as a printed circuit board (PCB) carrier, substrate or submount 23 . A metal reflector 24 mounted on submount 23 surrounds LED chip 22 and reflects light emitted by LED chip 22 away from package 20 . Reflector 24 also provides mechanical protection for LED chip 22 . One or more wire bond connections 21 are made between the ohmic contacts on the LED chip 22 and the electrical traces 25A, 25B on the submount 23 . The mounted LED chip 22 is then covered with an encapsulant 26, which provides environmental and mechanical protection for the chip while also acting as a lens. Typically, the metal reflector 24 is attached to the carrier by solder or epoxy bonding.

Different LED packages, such as those shown in Figures 1 and 2, regardless of size, can be used as light sources for billboards and displays. Large-screen LED-based displays, often referred to as giant screens, are becoming more common in many indoor and outdoor settings, such as at stadiums, racetracks, concerts, and in large public areas such as Times Square in New York City. Some of these displays or screens may be as large as 60 feet high and 60 feet wide. As technology advances, expect to develop larger screens.

These screens can include thousands of "pixels" or "pixel modules," each of which can contain multiple LEDs. The pixel modules can use high-efficiency, high-brightness LEDs that allow the display to be visible from a relatively long distance, even during daylight conditions. In some billboards, each pixel can have a single LED chip, and a pixel module can have as few as 3 or 4 LEDs (one red, one green, and one blue), which allows the pixel to switch from red to green. Many different colors of light are emitted in combination with blue light and/or blue light. In the largest giant screens, each pixel module can have dozens of LEDs. These pixel modules are arranged as a rectangular grid. In one type of display, the grid can be 640 modules wide and 480 modules high, and the size of the screen depends on the actual size of the pixel modules.

An important aspect of conventional LED-based displays is the contrast between pixels in the display, which should be maximized for good image quality. Often times, increasing the contrast between pixels can lead to a decrease in the overall emission intensity of the emitters in the pixels and, as a result, the overall emission intensity of the LED display.

To improve the contrast ratio of LED displays, LED packages have been developed that have a surface area surrounding the LED chip that contains a color that contrasts with the light emitted from the LED chip. However, these packages only use red, green and blue LEDs as their light sources. It is generally believed that the light emitted by an LED package employing such an arrangement may contain both the light of the LED chip and the light of the conversion material (eg, white light), and that employing such an arrangement would result in an unacceptable loss of brightness of the emitted light. The concern is that the contrasting surface area surrounding the LED chip absorbs package light, thus reducing the overall brightness of the package and of the billboards or displays utilizing these packages.

Utility model content

The present invention is directed to emitter packages, more particularly to LED packages and LED displays utilizing LED packages. An LED package according to the present invention employs an LED chip and a conversion material that converts at least some of the light from the LED chip.

An embodiment of an LED package according to the invention comprises an LED chip and a conversion material arranged to convert at least some of the light emitted from the LED chip. The package emits light from the conversion material or a combination of light from the conversion material and the LED chip. A reflective area is included around the LED chip that substantially reflects the encapsulated light, and a contrasting area is included outside the reflective area that has a color that contrasts with the encapsulated light.

One embodiment of the LED display according to the invention comprises a plurality of LED packages mounted in relation to each other to generate a message or image. At least some of the LED packages include an LED chip and a conversion material disposed in the reflective cup, the conversion material converting at least some of the light emitted from the LED chip. The LED package emits encapsulated light from the conversion material or a combination of light from the conversion material and the LED chip. The reflective area substantially reflects the encapsulation light, and the encapsulation further includes a contrasting area outside the reflective area and having a color that contrasts with the encapsulation light.

Another embodiment of an LED package according to the invention comprises an LED chip and a conversion material arranged to absorb light from the LED chip and re-emit the light at a different wavelength. The package emits packaged light which includes re-emitted light or a combination of light from the LED chip and re-emitted light. The LED chip is mounted within a reflective cup having an upper surface with a color that contrasts with light emitted from the LED chip.

Another embodiment of an LED package according to the present invention comprises a plurality of LED chips electrically coupled in a single loop. The surface immediately surrounding the LED chip comprises a reflective area which substantially reflects the light emitted from the LED chip. A contrasting area is included that is outside the reflective area and has a color that contrasts with the light emitted from the LED chip.

The utility model provides an LED package, which comprises: a plastic casing; an LED chip arranged in the casing and a conversion material configured to convert at least some light emitted from the LED chip, the LED package emits encapsulating light from the conversion material or emitting a combination of light from the conversion material and the LED chip; a reflective area surrounding the LED chip that substantially reflects the encapsulated light; and A contrasting area outside the area, the contrasting area having a color that contrasts with the encapsulated light.

Further, the encapsulated light includes blue-shifted yellow light.

Further, the encapsulated light includes white light.

Further, the LED chip is electrically coupled to the lead frame.

Further, the LED package further includes a casing, wherein the reflective area includes a cavity in the casing, and the LED chip is installed in the cavity.

Further, the cavity forms a reflective cup surrounding the LED chip.

Further, the LED package includes a surface mount device.

Further, the reflection area includes a reflection cup.

Further, the contrasting area is black.

Further, the contrast area surrounds the reflective area.

Further, the contrast area is at the level above the LED chip.

Further, the contrasting area and the LED chip are arranged such that the LED light is emitted from the LED package and not directly on the contrasting area.

The utility model provides a light-emitting diode (LED) display, which includes: a plurality of LED packages, at least some of the LED packages include a plastic casing, an LED chip arranged in the casing and a conversion material arranged in a reflective cup. The conversion material converts at least some of the light emitted from the LED chip, the at least some of the LED packages emit encapsulated light from the conversion material or a combination of light from the conversion material and the LED chip, the reflective An area substantially reflects packaged light, the LED package further comprising a contrasting area outside of the reflective area and having a contrasting color to the encapsulated light.

Further, the LED display contains a higher pixel contrast ratio than the same LED display with the LED package without the contrast area.

Further, the reflective area of each of the at least some LED packages includes a reflective cup surrounding the LED chip.

Further, each of said at least some LED packages comprises a surface mount device (SMD).

Further, each of the at least some LED packages emits white light.

Further, each of the at least some LED packages emits blue-shifted yellow BSY light.

Further, the contrast area in each of the at least some LED packages is black.

Further, the contrasting area in each of the at least some LED packages surrounds the reflective area.

Further, the contrast region in each of the at least some LED packages is at a level above the LED chip.

Further, the contrast area is arranged in each of the at least some LED packages such that LED light is emitted from the LED packages and not directly on the contrast area.

The utility model provides an LED package, which comprises: a plastic casing, an LED chip arranged in the casing and a conversion material arranged to absorb light from the LED chip and re-emit light of different wavelengths, The LED package emits packaged light comprising the re-emitted light or a combination of light from the LED chip and the re-emitted light, the LED chip being mounted in a reflective cup, the reflected The cup has a colored upper surface that contrasts with the light emitted from the LED chip.

Further, the surface of the reflective cup fully reflects the packaged light.

Further, the surface of the reflective cup is white.

Further, the upper surface is black.

Further, the LED package includes a surface mount device.

Further, the upper surface and the LED chip are arranged such that LED light is emitted from the LED package and not directly on the upper surface.

The utility model provides an LED package, which comprises: a plastic casing; a plurality of LED chips arranged in the casing and electrically coupled in a single circuit, wherein the surface directly surrounding the LED chips includes a reflective area and a contrasting an area, the reflective area sufficiently reflects the light emitted from the LED chip, and the contrast area is located outside the reflective area and has a color contrasting with the light emitted from the LED chip.

Further, the single circuit includes a single anode and a single cathode for applying an electrical signal to the LED chip.

Further, at least some of the LED chips emit white light.

Further, at least some of the LED chips emit blue-shifted yellow light.

Further, the reflective area includes a cavity in the casing, and the LED chip is installed in the cavity.

Further, the cavity forms a reflective cup surrounding the LED chip.

Further, the LED package includes a surface mount device (SMD).

Further, the reflection area includes a reflection cup.

Further, the contrasting area is black.

Further, the contrast area surrounds the reflective area.

Further, the contrast area is at the level above the LED chip.

The invention is particularly suitable for LED packages that can be installed in billboards or displays to generate messages or images. The LED package provides LED billboards as well as good contrast between different pixels in the display without reducing the perceived luminous flux or brightness of the display.

These and other aspects and advantages of the invention will become apparent from the ensuing detailed description and accompanying drawings illustrating features of the invention, illustrating by way of example.

Description of drawings

FIG. 1 is a side view of a conventional light emitting diode package;

2 is a perspective view of another conventional LED package;

3 is a perspective view of an embodiment of an LED package according to the present invention;

Fig. 4 is a top view of the LED package shown in Fig. 3;

Fig. 5 is a sectional view of the LED package shown in Fig. 4 along section line 5-5;

Fig. 6 is a side view of an embodiment of the LED display according to the present invention;

7 is a perspective view of another LED package according to the present invention;

Figure 8 is a top view of the LED package shown in Figure 7; and

Fig. 9 is a schematic diagram illustrating the interconnection between LED chips in one embodiment of the LED package according to the present invention.

Detailed ways

The utility model is directed to LED packages and LED displays using LED packages, wherein the LED packages include different arrangements to improve the emission contrast between adjacent LED packages in the display. These packages may include one or more LED chips mounted on a submount or in a package housing and conversion material. A portion of the exterior surface of the submount or housing may comprise a color that contrasts with the color of light emitted from the LED package.

In some embodiments, the area of the submount or housing immediately surrounding the LED chip may comprise a material that is substantially the same color as or reflects light from the LED chip. Such a reflective area may at least partially comprise a reflective cup. Areas of the submount outside such reflective areas may comprise a material that contrasts with the LED chip light. In embodiments having a white emitting LED chip, the area immediately surrounding the LED chip can include a material that reflects white light, while the area surrounding the white light reflective material can contrast white light. In some of these embodiments, the white light reflective material can be white and the contrasting areas can be black. It will be appreciated that the contrasting regions may be many other colors including, but not limited to, blue, brown, gray, red, green, and the like.

This combination of reflective material and contrasting material provides improved contrast between the light emitted from the LED chip and the surrounding packaging. This contrast helps to provide contrast between LED packages used in LED displays, thereby providing contrast between different pixels in the display. This improved contrast can produce a higher quality image for the viewer. At the same time, LED packages employing white-emitting LED chips provide the unexpected result of not absorbing unreasonable amounts of light from the LED package. It was previously believed that employing such an arrangement with white or other wavelength converted light would result in excessive loss of packaged light. Although some of the light from the LED chips may be absorbed by the contrast material, when they are used in a display, the contrast can cause the viewer to unexpectedly perceive substantially the same amount of light as compared to a display with an LED package without the contrast material. The contrast compensates for any absorbed light so that the viewer perceives substantially the same image brightness from the display.

Embodiments are described below with reference to LED packages that emit at least some of the LED light that is wavelength converted. This typically involves an LED chip arranged with a conversion material, such as a phosphor, through which at least some of the LED light passes so that some of the LED light is absorbed by the conversion material and re-emitted at a different wavelength of light. In some of these embodiments, the LED package can emit light that is a combination of light from the LED and the conversion material. The wavelength-converted light may include light of different colors, including white light and blue shifted yellow (BSY) light of different color temperatures. Typically, BSY light involves a blue emitting LED covered by a yellow/green conversion material, wherein at least some of the blue LED light is converted by the conversion material. The resulting LED chip emits a combination of blue light from the LED and yellow/green light from the conversion material.

The package according to the present invention may also include a plurality of LED chips, each LED chip producing white wavelength-converted light. In other embodiments, an LED package may utilize multiple chips that emit different colors of light that are arranged to combine to produce white light. Techniques have been developed to generate white light from multiple discrete light sources to provide improved CRI at the desired color temperature, using different hues from different discrete light sources. Such a technique is described in U.S. Patent No. 7,213,940, entitled "Lighting Device and Lighting Method." In one such arrangement, a blue InGaN LED with a peak at 452nm is coated with a yellow conversion material, such as a YAG:Ce phosphor, to provide a yellow that is clear and has a blackbody locus that stays well on the CIE chart. The color of the color point (color point). Blue-emitting LEDs coated with yellow-converting materials are often referred to as blue-shifted yellow (BSY) LEDs or LED chips. The BSY emission is combined with light from the reddish AlInGaP LED, which "pulls" the yellow color of the yellow LED towards the blackbody curve to produce mild white light.

In multiple LED chip embodiments, the LED chips can be coupled in the package so that an electrical signal can be applied to each LED chip to turn them on or off, or to cause them to emit a desired intensity of light. In other embodiments, the LED chips may be coupled together so that a single electrical signal controls the LED chips to turn on or off. These embodiments may include LED chips coupled together in series.

LED packages according to the invention can be used in LED billboards and displays, but it will be appreciated that they can be used in many different applications. LED packages can comply with various industry standards, making them suitable for use in LED-based signage, channel letter lighting, or general backlighting and lighting applications. Some embodiments may also include flat top emitting surfaces to make them compatible with light pipes. These are but a few of the many different applications for LED packages according to the invention.

Some LED package embodiments according to the present invention may include a single LED chip or multiple LED chips mounted to a submount or housing. These packages may also include a reflective cup surrounding the LED chip or LED chips. The upper surface of the reflective cup surrounding the LED chip may include a material that contrasts with the light emitted by the LED chip. Portions of the submount exposed within the cup, and/or reflective surfaces within the cup may also include a material that reflects light from the LED chip. In some of these embodiments, the light emitted from the LED chip can be white or other wavelength converted light, and the surface of the submount within the reflective cup and the reflective surface of the cup can be white or reflect white or wavelength converted light. The contrasting upper surface of the reflective cup can be many different colors, but in some embodiments is black.

The invention has been described herein with reference to some embodiments, but it will be understood that the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In particular, many different LED chip, reflective cup, and leadframe arrangements beyond those described above can be provided, and the encapsulant can provide additional advantages for improved reliability and emission characteristics from the LED package and LED displays using the LED package. feature. Although the different embodiments of LED packages discussed below are directed to use in LED displays, LED packages can also be used in many different lighting applications.

It will also be understood that when an element such as a layer, region or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. Also, relative terms such as "above" and "below" and similar terms may be used herein to describe the relationship of one layer or another region. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

Although the terms first, second, etc. may be used herein to describe various elements, components, regions and/or sections, these terms shall not limit these elements, components, regions and/or sections. These terms are only used to distinguish one element, component, region or section from another element, component, region or section. Thus, a first element, component, region or section discussed below could be termed a second element, component, region or section without departing from the teachings of the present invention.

Embodiments of the invention are described herein with reference to cross section illustrations that are schematic illustrations of embodiments of the invention. Accordingly, the actual thickness of the components may vary and variations from the illustrated shapes are contemplated for reasons such as manufacturing techniques and/or tolerances. Embodiments of the invention are not to be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes for, for example, manufacturing reasons. Typically, square or rectangular regions illustrated or described will have rounded or arcuate features due to standard manufacturing tolerances. The regions shown in the figures are thus schematic in nature and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the scope of the invention.

3-5 illustrate one embodiment of an emitter package 50 including a surface mount device (SMD) according to the present invention. That is, the device is arranged so that it can be mounted to a structure such as a printed circuit board (PCB) by employing surface mount technology. It is understood that the present invention is also applicable to other emitter package types than SMD, such as pin mount emitter packages. Package 50 includes a housing (or submount) 52 carrying an integrated leadframe 53 . Leadframe 53 includes a plurality of conductive connections for conducting electrical signals to the packaged light emitters and also for helping to dissipate heat generated by the emitters.

The lead frame 53 can be arranged in many different ways, and different numbers of components can be employed in different package embodiments. Package 50 is described below as utilizing an emitter to which, in the illustrated embodiment, leadframe 53 is arranged to apply electrical signals. Lead frame 54 includes conductive members 54a-d, two of which are used to apply electrical signals to the emitters. In the illustrated embodiment, the anode for applying an electrical signal to the transmitter may be the second conductive member 54b and the cathode may be the fourth conductive member 54d, but it will be appreciated that other embodiments may utilize conductive members 54a- d the rest of the conductive parts. The remaining conductive components 54a and 54c may be included to provide mounting stability and to provide an additional thermal path to dissipate heat from the emitter. In the illustrated embodiment, the second conductive member 54b has a die attach pad 56 for mounting an emitter such as a light emitting diode (LED).

Housing 52 can have many different shapes and sizes, and in the illustrated embodiment, it is generally square or rectangular, with upper and lower surfaces 58 and 60, first and second side surfaces 62 and 64, and first and second end surfaces 66 and 68 . The upper portion of the housing further includes a recess or cavity 70 extending from the upper surface 58 into the body of the housing 52 up to the lead frame 53 . The package emitter is arranged on the leadframe 53 so that light from the emitter is emitted from the package 50 through the cavity 70 . Cavity 70 constitutes a reflective cup surrounding the emitter to help reflect the emitter light out of package 50 . In some embodiments, a reflective insert or ring (not shown) may be placed and secured along at least a portion of the side or wall 74 of the cavity 70 . The effect of the reflectivity of the ring and the emission angle of the package can be enhanced by tapering the cavity 70 and carrying the ring inwardly towards the interior of the housing. As an example, a reflection angle of about 50 degrees provides suitable reflectivity and viewing angle.

In some embodiments, the cavity 70 may be at least partially filled with a filler material (or encapsulant) 78 such that the filler material (or encapsulant) 78 protects and positionally stabilizes the lead frame 53 and the mounted emitter. In some cases, filler material 78 may cover the emitters and portions of leadframe 53 exposed through cavity 70 . Fill material 78 may be selected to have predetermined optical properties to enhance projection of light from the LED, and in some embodiments, fill material 78 is substantially transparent to light emitted by the encapsulated emitter. Fill material 78 may also be flat so that it is approximately level with upper surface 58, or it may be shaped as a lens, such as a hemisphere or a bullet. Alternatively, the filling material may be fully or partially recessed into cavity 760 . Filler material 78 may be formed from resin, epoxy, thermoplastic polycondensate, glass, and/or other suitable material or combination of materials. In some embodiments, materials for enhancing the emission, absorption, and/or scattering of light to and/or from the LEDs may be added to the fill material 78 .

Housing 52 may be fabricated from a material that is preferably both electrically insulating and thermally conductive. Such materials are well known in the art and may include, without limitation, certain ceramics, resins, epoxies, thermoplastic condensation polymers (such as polyphthalamide (PPA)), and glass. Package 50 and its housing 52 may be formed and/or assembled by any of a variety of known methods well known in the art. For example, housing 52 may be formed or molded around conductive components 54a-d, such as by injection molding. Alternatively, the housing may be formed in multiple parts, such as a top and a bottom, on which the conductive member is formed. The top and bottom may then be bonded together using known methods and materials, such as by epoxy, adhesive, or other suitable bonding material.

Many different emitters can be used with packages according to the invention, and package 50 utilizes LED chips 80 . Different embodiments may have different LED chips that emit different colors of light, and in the embodiment shown, package 50 includes LED chips that emit white or other wavelength-converted light.

LED structures, features, and their manufacture and operation are generally known in the art and are only briefly discussed here. LEDs can have many different semiconductor layers arranged in different ways and can emit different colors. The layers of the LED can be fabricated using known processes, and one suitable fabrication process is the use of metal organic chemical vapor deposition (MOCVD). The layers of an LED chip typically include an active layer/region sandwiched between first and second oppositely doped epitaxial layers, all of which are formed continuously on a growth substrate or wafer. The LED chips formed on the wafer can be singulated and used in various applications, such as being mounted in a package. It is understood that the growth substrate/wafer may remain as part of the final singulated LED or the growth substrate may be removed in whole or in part.

It is also understood that additional layers and elements may also be included in the LED, including but not limited to buffer layers, nucleation layers, contact layers, and current spreading layers, as well as light extraction layers and elements. The active region may include single quantum well (SQW), multiple quantum well (MQW), double heterojunction or superlattice structures.

The active region and doped layers can be fabricated from different material systems, one such system is a Ill-nitride based material system. Group III nitrides refer to those semiconductor compounds formed between nitrogen and an element in Group III of the periodic table, usually aluminum (Al), gallium (Ga), and indium (In). The term also refers to ternary and quaternary compounds such as aluminum gallium nitride (AlGaN) and aluminum indium gallium nitride (AlInGaN). In a possible embodiment, the doped layer is gallium nitride (GaN) and the active layer is InGaN. In alternative embodiments, the doped layer may be AlGaN, aluminum gallium arsenide (AlGaAs) or aluminum gallium indium arsenide phosphide (AlGaInAsP) or aluminum indium gallium phosphide (AlInGaP) or zinc oxide (ZnO).

The growth substrate/wafer can be made of many materials such as silicon, glass, sapphire, silicon carbide, aluminum nitride (AlN), gallium nitride (GaN), a suitable substrate is 4H polytype silicon carbide, however also Other silicon carbide polytypes including 3C, 6H and 15R polytypes may be used. Silicon carbide has certain advantages such as a closer lattice match to Ill-nitride than sapphire, thus resulting in Ill-nitride films of higher quality. Silicon carbide also has very high thermal conductivity so that the total output power of a Ill-nitride device on silicon carbide is not limited by heat dissipation from the substrate (as may be the case with some devices formed on sapphire). SiC substrates are available from Kerry Research, Durham, NC, USA, and methods for making them are set forth in the scientific literature and in US Patent Nos. Re. 34,861, 4,946,547, and 5,200,022. LEDs can also include additional features, such as conductive current spreading structures and current spreading layers, all of which can be made from known materials deposited using known methods.

The LED chip 80 may be electrically coupled to the attachment pad 56 on the second conductive member 54b by an electrically and thermally conductive bonding material such as solder, adhesive, coating, film, encapsulant, Paste, grease and/or other suitable materials. In a preferred embodiment, the LEDs can be electrically coupled and secured to their respective pads using solder pads on the bottom of the LEDs so that the solder is not visible from the top. A bonding wire 82 may be included and extend between the LED chip 80 and the fourth conductive member 54d. An electrical signal applied across the second and fourth conductive members causes LED chip 80 to emit light.

Fabrication of the conductive features 54a-d may be accomplished by stamping, injection molding, cutting, etching, bending, or by other known methods and/or combinations of methods to achieve the desired configuration. For example, conductive components 54a-d may be partially metal stamped (eg, simultaneously stamped from a single sheet of relevant material), bent appropriately, and completely separated or completely separated after forming some or all of the housings.

Conductive members 54a-d may be fabricated from conductive metals or metal alloys, such as copper, copper alloys, and/or other suitable low resistivity corrosion resistant materials or combinations of materials. As noted, the thermal conductivity of the leads can somewhat assist in conducting heat away from the LED chip 80 .

Some or all of the LED chips described herein may be coated with a conversion material such as one or more phosphors that absorb at least some of the LED chip light and emit light at a different wavelength so that the LED chip emits light from the LED chip and the phosphor. Combination of light from the body (ie, wavelength-converted light). In other embodiments, the conversion material may be located in other areas of the package, including but not limited to encapsulants or surfaces of the package such as reflective cups.

In one embodiment according to the present invention, the white emitting LED chip may comprise an LED chip that emits light in the blue wavelength spectrum, while the phosphor absorbs part of the blue light and re-emits yellow light. The LED chip emits white light which is a combination of blue light and yellow light. In other embodiments, the LED chips emit a combination of blue and yellow non-white light, as described in the above-mentioned US Patent No. 7,213,940. In some embodiments, the phosphor comprises commercially available YAG:Ce, however, using a (Gd,Y) ₃ (Al,Ga) ₅ O ₁₂ :Ce based system such as Y ₃ Al ₅ O ₁₂ :Ce( YAG)) phosphors made of conversion particles, the whole range of broad yellow spectral emission is possible. Other yellow phosphors that can be used in white-emitting LED chips include: Tb _3-x RE _x O ₁₂ :Ce(TAG); RE=Y, Gd, La, Lu; or Sr _2-xy Ba _x Ca _y SiO ₄ : Eu.

Alternatively, in other embodiments, the LED chip emits light of other colors by coating it with a desired conversion material, such as a phosphor, that provides the desired emission. For example, a red emitting LED chip may include an LED chip covered with a phosphor that absorbs light from the LED chip and emits red light. LED chips can emit blue or UV light, and some phosphors suitable for these structures can include: Lu ₂ O ₃ :Eu ³⁺ ; (Sr _2-x La _x )(Ce _1-x Eu _x )O ₄ ; Sr _{2 -x} Eu _x CeO ₄ ; SrTiO ₃ :Pr ³⁺ , Ga ³⁺ ; CaAlSiN ₃ :Eu ²⁺ ; and Sr ₂ Si ₅ N ₈ :Eu ²⁺ .

LEDs can be coated with phosphors in a number of different ways, one suitable method is described in U.S. Patent Application Serial Nos. 11/656,759 and 11/899,790, both of which have utility model titles is "Wafer Level Phosphor Coating Method and Devices Fabricated Utilizing Method", and both are incorporated herein by reference. Alternatively, other methods can be used to coat the LEDs, such as electrophoretic deposition (EPD), a suitable EPD method is described in U.S. Patent Application No. 11/473,089 with the utility model title "Close Loop Electrophoretic Deposition of Semiconductor Devices" , which is also incorporated herein by reference. Additionally, LEDs can have vertical or lateral geometries, as is known in the art. Those comprising vertical geometries may have a first contact on the substrate and a second contact on the p-type layer. An electrical signal applied to the first contact propagates into the n-type layer, and a signal applied to the second contact propagates into the p-type layer. In the case of Ill-nitride devices, it is known that a thin translucent layer typically covers part or all of the p-type layer. It will be appreciated that the second contact may comprise a layer, typically a metal, such as platinum (Pt), or a transparent conducting oxide, such as indium tin oxide (ITO).

LEDs can also include lateral geometries where both contacts are on top of the LED. The p-type layer and a part of the active region are removed by etching to expose the contact mesa on the n-type layer. A second lateral n-type contact is provided on the mesa of the n-type layer. These contacts may comprise known materials deposited using known deposition techniques.

In the illustrated embodiment, package 50 is arranged so that upper surface 58 has a contrasting color to light emitted from package 50 through recess/cavity 70 . In most embodiments, the light emitted from cavity 70 may include light emitted by LED chip 80, but in other embodiments, the light emitted through cavity 70 may also include light emitted by a conversion material located at a different location in the package. Converted light. This may include the conversion material over the LED chip 80 , the conversion material mixed in the fill material 78 , or the conversion material on the surface exposed in the recess 70 .

In the illustrated embodiment, LED package 50 emits white light from recess 70, and the upper surface may include a color that contrasts with the white light. Many different colors can be used, such as blue, brown, gray, red, green, purple, etc., and in the embodiment shown, its upper surface 58 is black. Black pigments can be applied using many different known methods. The application can be done during the molding of the housing 52 or at a later step in the package manufacturing process using different methods such as screen printing, inkjet printing, painting, etc.

To further contrast the recess or cavity from the contrasting color of the upper surface 58, the surface in the recess may also be colored or coated with a material that sufficiently reflects light emitted from the LED and/or surrounding conversion material . In some embodiments, the surfaces visible through the recess sidewalls 74 and other surfaces of the housing may include a material that substantially reflects light from the LED chips 80 . Both the surfaces of the conductive features 54a-d exposed by the recesses 70 and the spaces between the conductive features 54a-d can be further coated with a reflective layer (not shown) to improve the performance of the LED display by reflecting light from the LED chip 80. Reflection of light emitted by the LED chip 80 that would otherwise be absorbed by these packaging components. Preferably, the reflective layer comprises silver, but it will be appreciated that other reflective materials, such as aluminum, may also be provided in various thicknesses. The reflective layer may completely or partially cover the portion of the conductive member not occupied by the LED chip 80 or the bond wire 82, but it will be appreciated that, as a general fact, the more area covered by the reflective layer, the greater the reflective area obtained, which The overall package reflectivity can be improved.

Cavity 70 may have many different shapes, such as circular as shown, or oval, square, rectangular, or other polygonal shapes. The contrasting area of upper surface 58 can have many different shapes and can cover all or less than all of the upper surface. In an embodiment, upper surface 58 may be covered by a contrasting material, the shape of which is defined by the shape of upper surface 58 .

As discussed above, the darker contrasting color of upper surface 58 may result in absorption of certain light as it is emitted from LED chip 80 and exits package recess 70 . To help minimize the amount of LED light that is absorbed, upper surface 58 may be arranged so that it is above the LED chips so that little or no LED light is emitted directly onto the upper surface. That is, the LED chip 80 is disposed at the base of the cavity 70 , while the upper surface 58 is on top of the reflective cup, which is above the LED chip 80 . As a result, light from LED chip 80 is emitted out of cavity 70 and not directly onto upper surface 58 . This combination of contrasting materials provides the contrasting advantages mentioned above, with the unexpected effect of little or no perceived reduction in LED package (or LED display brightness) due to light from the emitter being absorbed by the darker surface .

As mentioned above, LED package embodiments according to the present invention can be used in many different applications, but are particularly suitable for use in LED displays to provide a sloped peak emission pattern. FIG. 6 shows an embodiment of an LED display 100 according to the present invention, which can utilize multiple LED packages 102 according to the present invention to improve pixel contrast. Different LED display embodiments can have all or several contrast-improved LED packages. . Different LED displays according to the invention may have more than 300,000 pixels, while other embodiments may have 200,000 to 300,000 pixels. Other embodiments may have between 100,000 and 200,000 pixels.

It will be appreciated that different embodiments of LED packages according to the present invention can be arranged in many different ways and have many different components. Different embodiments can have multiple emitters or LED chips, Figures 7 and 8 show another embodiment of an LED package 200 according to the invention, also arranged as SMD, but with 3 LED chips. Like the above embodiments, package 200 includes a housing 202 carrying an integrated leadframe 204 . The leadframe 204 includes a plurality of conductive connections for conducting electrical signals to the packaged light emitters and also assisting in dissipating heat generated by the emitters.

The leadframes are arranged so that each emitter is driven by a respective electrical signal. Thus, in the illustrated embodiment there are 6 conductive members comprising a pair of conductive members for each emitter through which the electrical signal is applied to each emitter. For package 200, the conductive components include first, second and third anode components 206, 208, 210, and first, second and third cathode components 212, 214, 216 each having an emitter attachment pad. The conductive member and the attachment pad can be made of the same materials as those described above.

Similar to the above, housing 202 is generally square or rectangular having upper and lower surfaces 218 and 220 , first and second side surfaces 222 and 224 , and first and second end surfaces 226 and 228 . The upper portion of the housing further includes a recess or cavity 230 that extends from the upper surface 218 into the body of the housing 202 to the leadframe 204 . The emitters are arranged on the lead frame 204 such that light from the emitters is emitted from the package 200 through the cavity 230 . In some embodiments, reflective inserts or rings (not shown) may be placed and secured along at least a portion of the sides or walls 234 of the cavity 230 .

As with package 50, in some embodiments, cavity 230 may be at least partially filled with filler material (or encapsulant) 238, such that filler material (or encapsulant) 238 can protect and positionally stabilize lead frame 204 and the carrier. launcher. Fill material 238 and housing 202 may be made from the same methods and materials as previously mentioned for package 50 .

In the illustrative embodiment described, package 200 utilizes first, second and third LED chips 240, 242, 244, each of which may emit the same color of light or a different color of light than the others. In the illustrated embodiment, the LED chips 240, 242, 244 can emit blue, green and red respectively, so that the combination of these LEDs produces substantially the full range of colors when properly powered. Further, the LEDs 240, 242, 244 emit white light combinations of different color temperatures when properly powered.

The cathode members 212, 214, 216 include a central surface or mounting pad for carrying LED chips 240, 242, 244 in a linear array extending in a direction 246 perpendicular to the side surfaces 222 and 224, typically the LEDs 240, 244, 242 , 244 are aligned along the central axis of housing 202 . Such alignment can provide improved color uniformity across viewing angles compared to packages with LEDs arranged in other fashions, such as in groups.

In the illustrated embodiment, package 200 is also arranged such that upper surface 218 has a color that contrasts with the color of light emitted from package 200 through cavity 230 . As previously discussed, this may include light from the LED chips 240, 242, 244 and/or light from one or more conversion materials disposed within the recess. In the illustrated embodiment, the LED package 200 may include an emitting LED chip 240 , 242 , 244 or a combination of white light that may emit light from its LED chip 240 , 242 , 244 . Upper surface 218 may include a color that contrasts with white light. Many different colors can be used, such as blue, brown, gray, red, green, purple, etc., and in the embodiment shown, its upper surface 218 is black. The black pigment can be applied using one of the methods described previously.

To further contrast the recess or cavity from the contrasting color of upper surface 218, the surfaces within recess 230 may also be colored or coated with a material that reflects light emitted from the LED and/or surrounding conversion material, such as discussed earlier. In addition, other surfaces exposed through recesses 230 may also be fully coated with a reflective layer (not shown), as well as spaces between conductive components may be fully coated with a reflective layer (not shown), as previously discussed. . The darker contrasting color of the upper surface 218 may result in absorption of certain light as it is emitted from the LED chips 240 , 242 , 244 and exits the package recess 230 . Similar to the above, to help minimize the amount of LED light that is absorbed, the upper surface 218 can be arranged so that it is above the LED chips so that little or no LED light directly shines on the upper surface. This arrangement provides the advantages discussed above, including improved pixel contrast without substantially reducing the perceived luminous flux or brightness of LED displays utilizing these packages.

The above embodiments have been described with reference to first, second and third anode and cathode components which allow for corresponding electrical signals to be applied to each LED chip, it being understood Fortunately, multiple LED chips can be coupled together in many other ways. LED chips can be coupled together in many different combinations of series and parallel interconnections. In some embodiments, the LED chips may be coupled together in a single loop between a single anode and a single cathode for applying electrical signals to the LED chips.

The interconnection circuit 300 shown in FIG. 9 illustrates one embodiment of a single loop arrangement according to the present invention. Multiple LED chips 302, 304, 306 may be interconnected in series between a single anode 308 and a single cathode 310 so that a single electrical signal applied to a first of the LED chips 302 causes all LED chips 302, 304, 306 to emit light . This allows a single electrical signal to control all LED chips to an on or off state. It can be understood that in other embodiments, the LED chips can be connected in parallel between a single anode and a single cathode, or can be other series/parallel combinations.

It will be appreciated that the different embodiments of the emitter package may be arranged in many different ways than the previously mentioned embodiments. Packages can have many different surface mount or other types of mounting arrangements and can include reflective cups of different shapes and sizes. Other embodiments may be arranged without a reflective cup, one of these embodiments comprising an LED chip or LED chips mounted to a submount. A light reflective and contrasting material can surround the LED on the submount, and in some embodiments, an encapsulant in the form of a lens can be molded over the LED chip.

Although the invention has been described in detail with reference to certain preferred configurations thereof, other versions are possible. Therefore, the spirit and scope of the present invention should not be limited to the versions described above.

Claims (22)

1. a LED encapsulation is characterized in that, comprising:

Plastic casing;

Be arranged on the led chip in the said shell and be set for the transition material of conversion from least some light of said led chip emission; Said LED encapsulation emission encapsulation light, said encapsulation light comprise from the light of said transition material or from the combination of the light of said transition material and said led chip;

Reflector space around said led chip; And

Contrast areas outside said reflector space, said contrast areas have the color that forms contrast with said encapsulation light.

2. the LED of claim 1 encapsulation is characterized in that, said LED encapsulation further comprises the lead frame that is located in the said shell, and said led chip is electrically coupled to said lead frame.

3. the LED of claim 1 encapsulation is characterized in that wherein said reflector space comprises the cavity in the said shell, and said led chip is installed in the said cavity.

4. the LED of claim 3 encapsulation is characterized in that said cavity forms the reflector around said led chip.

5. the LED of claim 1 encapsulation is characterized in that, said LED encapsulation comprises surface mounted device.

6. the LED of claim 1 encapsulation is characterized in that said reflector space comprises reflector.

7. the LED of claim 1 encapsulation is characterized in that said contrast areas is a black region.

8. the LED of claim 1 encapsulation is characterized in that said contrast areas is around said reflector space.

9. the LED of claim 1 encapsulation is characterized in that said contrast areas is in the level on the said led chip.

10. a LED encapsulation is characterized in that, comprising:

Plastic casing;

Be arranged in the said shell led chip be set for absorption from the lay equal stress on transition material of light of new emission different wave length of the light of said led chip; Said LED encapsulation emission encapsulation light; Said encapsulation light comprises the said light of emission again or the light and the said combination of light emitted again of said led chip; Said led chip is installed in the reflector, and this reflector has colored upper surface, and this color forms contrast with the light of launching from said led chip.

11. the LED of claim 10 encapsulation is characterized in that the surface of said reflector is a white surface.

12. the LED of claim 10 encapsulation is characterized in that said upper surface is a black surface.

13. the LED of claim 10 encapsulation is characterized in that, said LED encapsulation comprises surface mounted device.

14. a LED encapsulation is characterized in that, comprising:

Plastic casing;

Be arranged in the said shell and be electrically coupled to a plurality of led chips in the single loop; Wherein direct surface around said led chip comprises reflector space and contrast areas; The reflection of said reflector space is from the light of said led chip emission, and it is outer and have with light from said led chip emission and form the color that contrasts that said contrast areas is positioned at said reflector space.

15. the LED of claim 14 encapsulation is characterized in that said single loop comprises single anode and the single negative electrode that is used for the signal of telecommunication is applied to said led chip.

16. the LED of claim 14 encapsulation is characterized in that said reflector space comprises the cavity in the said shell, said led chip is installed in the said cavity.

17. the LED of claim 16 encapsulation is characterized in that said cavity forms the reflector around said led chip.

18. the LED of claim 14 encapsulation is characterized in that, said LED encapsulation comprises surface mounted device.

19. the LED of claim 14 encapsulation is characterized in that said reflector space comprises reflector.

20. the LED of claim 14 encapsulation is characterized in that said contrast areas is a black region.

21. the LED of claim 14 encapsulation is characterized in that said contrast areas is around said reflector space.

22. the LED of claim 14 encapsulation is characterized in that said contrast areas is in the level on the said led chip.

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