TWI620895B - Flexible led assembly and led light bulb - Google Patents

Abstract

A light-emitting diode bulb comprising a bendable filament and a conductive wire. The bendable filament comprises a substrate, a light emitting diode wafer, a conductive block, and a wavelength conversion layer. The substrate includes a first surface, a second surface, and a terminal. A light emitting diode wafer is formed over the first surface. A conductive block is formed over the first surface. The wavelength conversion layer directly contacts the light emitting diode wafer and the conductive block. The conductive line is formed on the first surface and extends outward beyond the terminal, and is electrically connected to the light emitting diode chip.

Description

Flexible LED assembly and LED bulb

Embodiments of the present invention relate to flexible light emitting diode assemblies, and more particularly to light emitting diode assemblies that can be used in full perimeter applications.

At present, you can already see the application of various LED products, such as traffic signs, taillights, headlights, street lights, computer lights, flashlights, LED backlights, etc. These products must undergo important packaging procedures in addition to the necessary LED wafer processing.

The main function of the LED package is to provide the necessary support for LED chip power, light and heat. Semiconductor products such as LED wafers, if exposed to the atmosphere for a long time, may be affected by moisture or environmental chemicals, causing deterioration in characteristics. In the LED package, epoxy resin is commonly used to coat the LED wafer as a method for effectively isolating the atmosphere. In addition, in order to achieve greater brighter and more power-saving goals, LED packaging also needs good heat dissipation and light extraction efficiency. If the heat generated when the LED chip emits light is not released in time, the heat accumulated in the LED chip adversely affects the characteristics, lifetime, and reliability of the device. Optical design is also an important part of the LED packaging process. How to more effectively derive light, the angle of illumination and the direction are the design priorities.

The packaging technology of white LEDs is more complicated. In addition to the heat problem, it is also necessary to consider the color temperature, color rendering index, and phosphor powder. Moreover, if the white LED is implemented by using a blue LED chip with yellow-green phosphor, the shorter the wavelength of the blue light, the greater the damage to the human eye, so it is necessary to effectively block the blue light in the package structure and avoid blue light leakage.

Embodiments of the present invention disclose a light emitting diode bulb comprising a bendable filament and a conductive wire. The bendable filament comprises a substrate, a light emitting diode wafer, a conductive block, and a wavelength conversion layer. The substrate includes a first surface, a second surface, and a terminal. A light emitting diode wafer is formed over the first surface. A conductive block is formed over the first surface. The wavelength conversion layer directly contacts the light emitting diode wafer and the conductive block. The conductive line is formed on the first surface and extends outward beyond the terminal, and is electrically connected to the light emitting diode chip.

1 is a perspective view of an LED assembly 100 in accordance with an embodiment of the present invention and a cutaway view in some locations. As shown, the LED assembly 100 is a flexible structure that can be crimped into a reel that can be cut to the appropriate length as needed to serve as a primary source of illumination (such as a light bulb). . Figure 1 contains cross-sectional views A, B and C showing the cutaway views of the LED assembly 100 at three different locations, respectively.

LED assembly 100 includes a flexible transparent substrate 106. In one embodiment, the flexible transparent substrate 106 is constructed of a non-conductive transparent material such as glass or resin. The flexible transparent substrate 106 has surfaces 102, 104 facing in opposite directions and sidewalls 120, 124 between the surfaces 102, 104. As shown in FIG. 1, the flexible transparent substrate 106 is substantially elongated and has two terminals 114 and 116. In this specification, transparency is only used to mean that light is transmitted through, which may be transparent or translucent, or semi-transparent. The thickness of the flexible transparent substrate 106 between the surfaces 102 and 104 may be 150 um or less.

Figure 2 is a cross-sectional view along the direction of the two terminals 114 and 116 in Figure 1. 3A and 3B are side views of the LED assembly 100 of Fig. 1 for surface 102 and surface 104, respectively.

A conductive section 105 is formed on the surface 102 of the flexible transparent substrate 106. For example, the conductive segment 105 may be formed on the surface 102 of the transparent substrate 106 through a printed circuit; or a pre-designed conductive layer pattern may be formed on the surface 102 by means of a mask. After first coating a conductive layer on the surface 102 of the flexible transparent substrate 106, the pattern of the conductive layer is formed by etching on the surface 102 according to a pre-designed conductive layer pattern on the mask. On the surface 102, the conductive segments 105 are more able to define different conductive segments 105. The composition of the conductive segment 105 may be a component of a light transmissive material relative to the light emitted by the LED assembly 100, such as ITO or a silver film.

In an embodiment of the invention, taking the blue LED wafer 108 as an example, each of the blue LED chips 108 affixed to the conductive segments 105 of the surface 102 may comprise only a single light emitting diode having a forward voltage of about 2 ~3V (hereinafter referred to as "low voltage chip"); or a plurality of LEDs connected in series, the forward voltage is greater than the low voltage chip, such as 12V, 24V, 48V, etc. (hereinafter referred to as "high voltage chip") ). Specifically, the high-voltage chip is formed by a semiconductor process on a common substrate to form a plurality of light-emitting diode units electrically connected to each other (ie, a light-emitting diode structure having at least a light-emitting layer), and the plurality of light-emitting diodes The unit has no individual substrates but is formed on a common substrate. The common substrate may be an epitaxial growth substrate or a non-elevation growth substrate.

In other embodiments, LEDs of other colors (not shown) that are not blue are more fixed on the surface 102 of the LED assembly 100. For example, in an embodiment, the surface 102 includes not only the blue LED chip 108 but also one or more LED chips (not shown), such as a red LED chip, a green LED chip, a yellow LED chip, etc. Blend to produce light of the appropriate color or color temperature. In addition, all or part of the LED chip can also be replaced by an LED package.

In FIGS. 1 , 2 , and 3A, the blue LED chip 108 is arranged in a line on the flexible transparent substrate 106 along the longitudinal axis direction formed by the two terminals 114 and 116. The anode and cathode of the blue LED chip 108 are electrically connected to two adjacent conductive segments 105, respectively. Therefore, the plurality of blue LED chips 108 are connected in series with each other in the conductive section 105, and can be electrically equivalent to a light-emitting diode having a high forward voltage. However, the present invention is not limited thereto. In other embodiments, the surface 102 includes a blue LED chip 108 or other color LED chips arranged in various patterns, and the electrical connection between the respective chips includes series and parallel connection. Or at the same time have a connection mode of series and parallel mixing.

In one embodiment, the blue LED wafer 108 is affixed to the conductive segment 105 in a flip chip manner by solder paste. The solder paste provides both mechanical support of the blue LED wafer 108 on the conductive segments 105 and electrical connection to the conductive segments 105. Although the solder paste is almost opaque, the effect of shading is almost negligible because of its small volume. In another embodiment, the blue LED chip 108 is adhered to the conductive segment 105 by an isotropic conductive paste; after forming the conductive segment 105, the isotropic conductive paste is coated on the conductive segment 105, and then The blue LED chip 108 is attached to the dissimilar conductive paste in a flip chip manner, so that the blue LED wafer 108 is fixed on the conductive segment 105 with an anisotropic conductive paste. In other embodiments, the blue LED wafer 108 is electrically connected to the conductive segment 105 in a eutectic alloy or silver paste.

In another embodiment, the blue LED chip 108 may also be disposed on the surface 102 of the flexible transparent substrate 106 without the conductive portion 105, and electrically connected to the conductive portion 105 through other electrical connections. . For example, the blue LED chip 108 is directly fixed on the surface 102 of the substrate 106 or the non-conductive heat dissipating material on the substrate 106, and then electrically connected to the conductive segment 105 and the blue LED wafer 108 by wire bonding.

Above the blue LED wafer 108 is a phosphor layer 110 as a wavelength conversion layer. The constituent material of the phosphor layer 110 may be a resin or a glass mixed with a wavelength converting material such as a phosphor powder or a dye, which may be partially blue (the dominant wavelength) emitted by the blue LED chip 108 Excited from 430 nm to 480 nm, yellow-green light (main wavelength between 430 nm and 480 nm) is generated, in which yellow-green light and the remaining blue light are more appropriately mixed into white light. 1 is only a schematic diagram. In an example, the LED assembly 100 may not be able to see the blue light under the phosphor layer 110 as shown in FIG. 1 because of the phosphor powder in the phosphor layer 110 covered. LED wafer 108. If the constituent material of the phosphor layer 110 is a resin, the resin may be a thermoplastic resin, a thermosetting resin or a photocurable resin. In other embodiments, the resin may be an epoxy resin, an acrylic resin or an anthrone resin.

In FIGS. 2 and 3A, the blue LED wafer 108 is completely covered by the phosphor layer 110, but the phosphor layer 110 does not cover all of the conductive segments 105. In the embodiment of Figures 2 and 3A, the phosphor layer 110 comprises a plurality of blocks of length and size, each block extending in a direction in which the two terminals 114 and 116 are joined and arranged in a line. There is a fixed distance between the block and the block, during which a portion of the conductive segment 105 is revealed. As shown in the cross-sectional view C in FIG. 1, the conductive segment 105 is not covered by the phosphor layer 110 and is exposed.

The phosphor layer 110 can be attached to the blue LED wafer 108 in an attached manner. In other embodiments, the phosphor layer 110 is formed in a dispensing manner on the blue LED wafer 108. Wherein, each block may cover only one or more blue LED chips 108; it is also possible that one block covers only one blue LED chip 108, and the other block covers a plurality of blue LED chips 108. The material of the phosphor layer 110 may be a resin or a silicone, and mixed with a monochromatic or multi-color phosphor material, for example, YAG, TAG or containing Sr, Ga, S, P, Si, O. A yellow fluorescent powder material or a green fluorescent powder material of components such as Gd, Ce, Lu, Ba, Ca, N, Si, Eu, Y, Cd, Zn, Se, and Al. For example, the material of the phosphor layer 110 may be an epoxy resin, an acrylic resin, or an anthrone resin. The phosphor material in the phosphor layer 110 may be garnet phosphor, phthalate phosphor, nitrogen compound phosphor or oxynitride phosphor. The phosphor material may also be yttrium aluminum garnet phosphor powder (YAG), yttrium aluminum garnet phosphor powder (TAG), Eu-activated alkaline earth silicate phosphor, or yttrium aluminum oxynitride. Compound fluorescent powder (Sialon).

The thickness of the phosphor layer 110 and the resulting block size can affect the degree of curling of the LED assembly 100. For example, if the phosphor layer 110 is thicker, or if the formed block is larger (the more blue LEDs 108 are covered), the LED assembly 100 may be more difficult to curl or have a smaller curvature.

As shown in FIG. 2 and FIG. 3B, the phosphor layer 112 is disposed on the surface 104 with respect to the phosphor layer 110 disposed on the surface 102, and the material and formation method of the phosphor layer 112 can be followed by The material of the toner layer 110 is similar or identical to the formation method as another wavelength conversion layer. In the LED assembly 100 of FIG. 3B, the phosphor layer 112 is also divided into a plurality of blocks arranged in a row with a substantially constant distance from each other. Basically, each of the blue LED chips 108 is located at a location of the corresponding surface 104 having at least one block of phosphor layer 112. However, a block of phosphor layer 112 may correspond to a single blue LED chip 108, or to a plurality of blue LED chips 108, or to a phosphor layer 110 corresponding to a single block, or to A single layer of phosphor powder layer 110. Briefly, each of the blue LED chips 108 is sandwiched by a phosphor layer 110 on the surface 102 and a phosphor layer 112 on the surface 104. In other embodiments, it is also possible to selectively provide only the phosphor layer 110 on the surface 102 without providing the phosphor layer 112. And the material of the phosphor layer 110 and the phosphor layer 112 may be the same or different materials, or materials containing the same chemical elements but being excited by light to emit light having different wavelengths.

In one embodiment, the surface 102 has a red LED wafer (not shown) that is sandwiched by the phosphor layer 110 and the phosphor layer 112 on the surface 104. In another embodiment, the phosphor layer 110 is overlaid on the red LED wafer of surface 102, but is substantially transparent and contains no or only a small amount (relative to the foregoing embodiment) of the phosphor material. Layers, such as silicone, epoxy, etc.; and red LED wafers, in the relative position of surface 104, have no phosphor layer 112 or only a small amount (relative to the previous embodiment) of the phosphor material.

As shown in the cross-sectional view of FIG. 1, the flexible transparent substrate 106 further has two side walls 120 and 124 between the surfaces 102 and 104. The side walls 120 and 124 do not cover or only partially cover the phosphor layer.

In fabrication, the LED assembly 100 can be cut with any cutting tool, such as scissors, to cut the conductive segments 105 where the phosphor layer 110 is not covered. As such, the LED assembly 100 can form a plurality of LED filaments, each of which is flexible. FIG. 4 shows an LED filament 130 implemented in accordance with the present invention, having two conductive segments 105 not covered by the phosphor layer 110 at both ends for electrically connecting the positive and negative terminals of a driving power source. Control causes the LED chips in the LED filament 130 to illuminate.

Figure 5 shows an LED bulb 200 in which an LED filament 130 implemented in accordance with the present invention is used. The LED bulb 200 has a bulb base 202, a lamp cover 204, a support frame 206, a conductive wire 207, and an LED filament 130-. The bulb base 202 can be an Edison standard, which includes an LED drive circuit 208. The lamp cover 204 is fixed to the bulb base 202 to form an accommodation space between the lamp cover 204 and the bulb base 202. The LED filament 130 is fixed in the accommodating space by the support frame 206. The support frame 206 may be substantially transparent or substantially transparent to the light emitted by the LED filament 130 to reduce the effect of shading. The LED filament 130 can be bent into a circle having a small indentation that is substantially perpendicular to the central axis of rotation 212 of the bulb base 202 and the globe 204. The conductive wire 207 and the support frame 206 are both fixed to the bulb base 202, and each support frame 206 is formed with a circle 209 surrounding the LED filament 130. As shown in Fig. 5, the support frame 206 connects the positions of the LED filaments 130 at both ends. In addition to the support frame 206, the two conductive wires 207 can also provide support for the LED filament 130 mechanism, and electrically connect the exposed conductive segments 105 at both ends of the LED filament 130 to the LED drive circuit 208 in the bulb base 202. . Therefore, the LED driving circuit 208 can drive the blue LED chip 108 in the LED filament 130 to illuminate through the conductive line 207 and the conductive segment 105.

The advantages of LED assembly 100 include:

1. The blue light leakage phenomenon can be reduced: in the embodiment, for the light generated by each blue LED chip 108, the direction in which the light travels is in addition to the direction facing the side walls 120 and 124, and other directions will be encountered. The phosphor layer 112 or the phosphor layer 110. That is, the light generated by the blue LED wafer 108 may only exit the LED assembly 100 from the sidewalls 120 and 124 without the phosphor layer. However, after experimental observation by the inventors of the present invention, when the sidewalls 120 and 124 are sufficiently thin, that is, the thickness between the surfaces 102 and 104 is thin enough, for example, less than 150 um, the light generated by the blue LED wafer 108 is not easily perceived by the sidewalls 120 and 124. To.

2. Six-sided illumination: Each of the blue LED chips 108 has substantially no opaque obstruction in the up, down, left, and right directions, so that it can be illuminated on six sides.

3. Convenient storage: After the LED assembly 100 is completed, it can be rolled into a tape or roller to facilitate inventory management.

4. Adjustable length: Appropriate selection of the material of the flexible transparent substrate 106 can be cut by using scissors or a blade.

5. Adjustable LED quantity: According to the forward voltage required for later application, an LED filament containing an appropriate number of LED chips can be cut. For example, if three blue LED chips 108 are connected in series between every two exposed conductive segments 105, it is simple to cut a filament of the blue LED wafer 108 with an integral multiple of three. If there is only one blue LED chip 108 between every two exposed conductive segments 105, then one of the filaments of any integer number of blue LED chips 108 can be clipped.

6. Simple assembly: the LED filament and the conductive wire 207 can be fixed by soldering, and the support frame 206 can be selectively disposed to support the LED filament 130 in the internal space of the bulb at different positions, and then the driving power source is electrically The conductive segments 105 that are connected to both ends of the LED filaments complete the assembly of the luminaire.

7. Suitable for full-circumference lamps: Take the LED bulb 200 in Fig. 5 as an example. Since the LED filament 130 is substantially curved into a circle having no directional difference with respect to the central rotation axis 212, and each of the blue LED chips can provide six-sided light, the condition that the lamp cover 204 is not covered by the opaque material Next, the LED bulb 200 is a luminaire that emits substantially full illumination.

Although the LED bulb 200 in Fig. 5 in which the LED filament 130 is substantially curved into a circular shape, the present invention is not limited thereto. The LED filament 130 can be bent into any shape for use in a suitable lighting device. Fig. 6 shows an LED bulb 300 in which the LED filament 130 is bent into a curved or curved shape and supported by two conductive wires in a bulb internal space. The LED bulb 400 in FIG. 7 includes an LED filament 130 that is placed in a transparent or translucent curved tube 410, wherein the LED filament 130 is curved along the internal passage of the bulb 410. Conductive sections 105, located at opposite ends of LED filaments 130, are soldered to conductive lines 404 or electrically connected to a plug (not shown). A driving power source (not shown) can illuminate the LED filament 130 through a conductive wire 404 or a plug. In another embodiment, the LED filament 130 can also serve as a light source for the channel letter.

As previously described, in the LED assembly implemented in accordance with the present invention, the LED chips are not necessarily all blue, and may be LED chips of other colors. In addition, not all blue LED chips must be covered by the same phosphor layer. In one embodiment, some of the blue LED chips 108 are covered by the phosphor layer 110, and some of the blue LED chips are covered by another layer of phosphor with different phosphors.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100‧‧‧LED components

102, 104‧‧‧ surface

105‧‧‧Electrical section

106‧‧‧Flexible transparent substrate

108‧‧‧Blue LED chip

110, 112‧‧‧Fluorescent powder layer

114, 116‧‧‧ Terminal

120, 124‧‧‧ side walls

130‧‧‧LED filament

200‧‧‧LED bulb

202‧‧‧Light bulb base

204‧‧‧shade

206‧‧‧Support frame

207‧‧‧Flexible wire

208‧‧‧LED drive circuit

209‧‧‧ circle

212‧‧‧Central rotation axis

300‧‧‧LED bulb

400‧‧‧Lighting device

404‧‧‧Flexible wire

410‧‧‧Translucent curved tube

A, B, C‧‧‧ section view

1 is a perspective view of an LED assembly 100 in accordance with an embodiment of the present invention and a cutaway view in some locations.

Fig. 2 is a cross-sectional view taken along the direction of the two terminals in Fig. 1.

3A and 3B are a top view and a bottom view of the LED assembly 100 in Fig. 1.

Figure 4 shows an LED filament in accordance with an embodiment of the present invention.

Figure 5 shows an LED bulb in accordance with another embodiment of the present invention.

Figure 6 shows an LED bulb in accordance with yet another embodiment of the present invention.

Figure 7 shows an illumination device employing an LED filament in accordance with an embodiment of the present invention.

Claims (10)

A light-emitting diode bulb comprising: a bendable filament comprising: a substrate comprising a first surface, a second surface, and a terminal; a light-emitting diode wafer formed on the first surface; a conductive block formed on the first surface; and a wavelength conversion layer directly contacting the light emitting diode chip and the conductive block; and a conductive line formed on the first surface and outward Exceeding the terminal and electrically connecting the LED chip. The light-emitting diode bulb of claim 1, wherein the substrate is flexible. The light-emitting diode bulb of claim 1, wherein the substrate further comprises a sidewall between the first surface and the second surface, the sidewall being not covered by the wavelength conversion layer. The light-emitting diode bulb of claim 1, wherein the conductive block comprises a portion that is not covered by the wavelength conversion layer. The light-emitting diode bulb of claim 1, wherein the conductive block does not exceed the terminal. The light-emitting diode bulb of claim 1, wherein the conductive block comprises an ITO or silver film. The light-emitting diode bulb of claim 1 further comprises a support frame surrounding the curved filament. A light-emitting diode bulb comprising: a bulb base; a lamp cover connected to the bulb base and defining an accommodation space; a curved substrate located in the accommodation space, including a surface and a terminal; a light-emitting diode chip disposed on the surface; a conductive block disposed on the surface; a wavelength conversion layer directly contacting the light-emitting diode wafer and the conductive block; a conductive line formed on The surface is above the terminal and electrically connected to the LED chip; and a support frame supports the curved substrate. The light-emitting diode bulb of claim 8, wherein the conductive block comprises a portion that is not covered by the wavelength conversion layer. The light-emitting diode bulb of claim 8, wherein the support frame comprises a support ring surrounding the curved substrate.