Patent Abstract:
An LED can include a pair of electrode members, an LED chip joined on top of a chip mounting portion disposed at an end of one of the pair of electrode members. The LED chip can be electrically connected to both of the pair of electrode members, and a clear resin portion can be formed to surround the LED chip. The clear resin portion can include a wavelength converting material mixed therein, wherein the LED chip emits ultraviolet, blue and/or yellow light, and wherein the wavelength converting material mixed in the clear resin portion converts light from the LED chip to green and red light that is longer in wavelength than the originally emitted light from the LED chip.

Full Description:
[0001]     This invention claims the benefit of Japanese patent application No. 2004-094774, filed on Mar. 29, 2004, and Japanese patent application No. 2004-094720, filed on Mar. 29, 2004, which are both hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to a light emitting diode (LED), and more particularly to an LED that emits light of so-called electric bulb color such as white, off-white, light blue, light yellow, etc.  
         [0004]     2. Description of the Related Art  
         [0005]     In recent years, there is an increasingly strong demand for power-saving and long-lasting lighting equipment from the viewpoint of preventing global warming, effectively using resources, and so on. In response thereto, LEDs are rapidly becoming shorter in wavelength and higher in brightness. Particular hope is placed on white LED&#39;s that use blue LED&#39;s for finding application in lighting.  
         [0006]     White LEDs that have a shell-shaped or surface-mount configuration are conventionally known. The conventional white LED is designed to externally emit white light by converting light from a blue LED chip to yellow light with a phosphor layer, and mixing the yellow light with blue light from the blue LED chip to create the white light.  
         [0007]     A conventional shell-shaped white LED is configured, for example, as shown in  FIG. 4 . That is, in  FIG. 4 , a white LED  1  includes a pair of lead frames  2  and  3 , and a blue LED chip  4  mounted on top of a chip mounting portion  2   a  formed on the upper end surface of the lead frame  2 . A phosphor layer  5  is formed surrounding the blue LED chip  4  on top of the chip mounting portion  2   a  of the lead frame  2  and includes phosphor  5   a  mixed therein. A lens portion  6  is formed with mold resin so as to surround the upper ends of the lead frames  2  and  3 , the blue LED chip  4 , and the phosphor layer  5 .  
         [0008]     The lead frames  2  and  3  are formed with a conductive material such as aluminum and are provided with the chip mounting portion  2   a  and bonding portions  2   b  and  3   a  at respective ends thereof. The other ends of the lead frames extend downward to make up terminal portions  2   c  and  3   b.    
         [0009]     The blue LED chip  4  is joined on top of the chip mounting portion  2   a  of the lead frame  2 , with two electrodes provided on the upper surface thereof electrically connected to the bonding portions  2   b  and  3   a  at the ends of the lead frames  2  and  3  by bonding wires  4   a  and  4   b . Here, the blue LED chip  4  is configured, for example, as a GaN chip and designed, when applied with a drive voltage via the lead frames  2  and  3 , to emit light having a peak wavelength of about 450 to 470 nm.  
         [0010]     The phosphor layer  5  is made, for example, of clear epoxy resin into which the phosphor  5   a  in fine particulate form is mixed. The phosphor layer  5  is formed and hardened on top of the chip mounting portion  2   a  of the lead frame  2 .  
         [0011]     As blue light from the blue LED chip  4  falls on the phosphor layer  5 , the phosphor  5   a  is excited, producing yellow light from the phosphor  5   a  and externally emitting white light as a result of mixing of the two lights. Here, the phosphor  5   a  includes a phosphor that emits a wide range of lights centering around yellow light such as YAG phosphor doped with cerium, TAG phosphor doped with cerium or orthosilicate phosphor (BaSrCa) SiO 4 , and is designed to produce a fluorescence, for example, with a peak wavelength of about 530 to 590 nm.  
         [0012]     The lens portion  6  is made, for example, of clear epoxy resin, and is formed such that it surrounds the whole area near the upper ends of the lead frames  2  and  3  centering around the blue LED chip  4  and the phosphor layer  5 .  
         [0013]     Based on the white LED  1  thus configured, the blue LED chip  4  emits light when a drive voltage is applied via the pair of lead frames  2  and  3 . The light falls on the phosphor  5   a  mixed into the phosphor layer  5 , exciting the phosphor  5   a  and producing yellow light. Then, this yellow light is mixed with blue light from the blue LED chip  4 , thus causing the mixture to be externally emitted as white light. In this case, white light has a spectrum distribution, for example, as shown in  FIG. 5 .  
         [0014]     On the other hand, a surface-mount white LED  7  can be configured, for example, as shown in  FIG. 6 . In  FIG. 6 , the white LED  7  includes a chip substrate  8 , a blue LED chip  4  mounted on top of the chip substrate, a frame-shaped member  9  formed on top of the chip substrate  8  so as to surround the blue LED chip  4 , and a phosphor layer  5  charged into a depressed portion  9   a  of the frame-shaped member  9 .  
         [0015]     The chip substrate  8  is made of a heat-resistant resin as a flat copper clad wired board, and is provided with a chip mounting land  8   a  and an electrode land  8   b  on the surface. Surface-mount terminal portions  8   c  and  8   d  extend around from these lands onto the lower surface via both end edges. The blue LED chip  4  is joined on top of the chip mounting land  8   a  of the chip substrate  8 , with the blue LED chip  4  electrically connected to the chip mounting land  8   a  and the electrode land  8   b  through wire-bonding.  
         [0016]     The frame-shaped member  9 , similarly formed on top of the chip substrate  8  with a heat-resistant resin, is provided with a recessed portion  9   a - a  portion in the form of an inverted truncated cone—so as to surround the blue LED chip  4 . It is to be noted that the inner surface of the recessed portion  9   a  is configured as a reflecting surface.  
         [0017]     Based on the white LED  7  thus configured, the blue LED chip  4  emits light when a drive voltage is applied via the surface-mount terminal portions  8   c  and  8   d , causing light to fall on the phosphor  5   a  mixed into the phosphor layer  5 , exciting the phosphor  5   a  and producing yellow light. Then, this yellow light is mixed with blue light from the blue LED chip  4 , thus causing the mixture to be externally emitted as white light.  
         [0018]     However, there are problems with the white LEDs  1  and  7  configured as described above. For example, blue light emitted from the blue LED chip  4  is converted in wavelength by the phosphor  5   a  to produce yellow light, with blue and yellow lights mixed together to emit white light. This white light has a color temperature, for example, of 5000 to 6000K. In contrast, an incandescent lamp (a lamp conventionally used over the last 100 plus years), has a color temperature, for example, of 2800 to 3000K.  
         [0019]     Incidentally, when a conventional white LED lamp is used in place of an incandescent lamp in lighting equipment, the white LED produced light appears as a bluish white light unlike the so-called electric bulb light color for an incandescent lamp (which appears as a warm-looking color tinged with red). This is true because the conventional white LED light has insufficient light intensity in the red region, as shown in  FIG. 5 , due to relatively high color temperature as described above, thus giving a cold impression.  
         [0020]     On the other hand, while a red phosphor that produces red light by excitation with blue light—a recent development—may be used, red phosphors are generally made of alkaline earth metal and therefore vulnerable to humidity, making it difficult to configure a highly reliable LED and difficult to obtain a sufficient intensity of red light.  
       SUMMARY OF THE INVENTION  
       [0021]     In light of the above, and in accordance with an aspect of the invention, a white LED light can be provided that emits warm-looking white light and which has a simple configuration.  
         [0022]     According to a second aspect of the invention there is provided an LED that can include a pair of electrode members, an LED chip joined on top of a chip mounting portion disposed at an end of one of the pair of electrode members, the LED chip being electrically connected to both of the pair of electrode members, and a clear resin portion formed such that it surrounds the LED chip. The clear resin portion can include a wavelength converting material mixed therein, wherein the LED chip emits ultraviolet, blue and/or yellow light, and wherein the wavelength converting material mixed in the clear resin portion converts at least part of the light from the LED chip to green and/or red light that is longer in wavelength.  
         [0023]     In the above-described LED, the pair of electrode members can include two lead frames extending parallel with each other. The LED can further include a lens portion made of a clear resin that surrounds both the LED chip and the clear resin portion. The pair of electrode members can also be configured with a conductive pattern formed on a chip substrate and which extends around onto the rear surface of the chip substrate to define surface-mount terminals. The clear resin portion can be charged into a recessed portion that is upwardly spread in such a manner as to expose a chip mounting portion formed on top of the chip substrate.  
         [0024]     The wavelength converting material can be configured to produce green light having a peak wavelength of about 535 to 560 nm and red light having a peak wavelength of about 620 to 640 nm as converted from the light originally emitted from the LED chip. The wavelength converting material can also contain thiogallate phosphor as a first phosphor and rare-earth-activated aluminate or rare-earth-activated orthosilicate as a second phosphor. The wavelength converting material can be dispersed in an alicyclic epoxy resin that does not containing phenyl radical or olefin-based resin.  
         [0025]     Based on the above configuration, a drive voltage can be applied to an LED chip via a pair of electrode members, thus allowing the LED chip to emit light. Then, ultraviolet, blue or yellow light emitted from the LED chip can be externally emitted via a clear resin portion. At this time, part of the light emitted from the LED chip can be directed to fall on a wavelength converting material within a clear resin portion, thus exciting the wavelength converting material and emitting green light having a peak wavelength of about 535 to 560 nm and red light having a peak wavelength of about 620 to 640 nm. Thus, ultraviolet, blue or yellow light and green and red light from the wavelength converting material can be mixed together, making it possible to obtain warm-looking white light having light characteristics in the red region. The white light has excellent color reproducibility, as compared with a conventional white LED that emits bluish white light by mixing blue light and yellow fluorescence.  
         [0026]     It is possible to obtain a shell-shaped LED by configuring the pair of electrode members as two lead frames extending parallel or substantially parallel with each other and further providing a lens portion made of a clear resin that surrounds both the LED chip and the clear resin portion.  
         [0027]     It is also possible to obtain a surface-mount LED by configuring the pair of electrode members as a conductive pattern formed on a chip substrate and including surface-mount terminals by extending the pattern around onto the rear surface of the chip substrate. The clear resin portion can be charged into an upwardly spread recessed portion so as to expose a chip mounting portion of a frame-shaped member formed on top of the chip substrate.  
         [0028]     A highly reliable LED can be obtained when the wavelength converting material contains thiogallate phosphor as a first phosphor and rare-earth-activated aluminate or rare-earth-activated orthosilicate as a second phosphor. The high resistance of these materials to humidity results in high reliability and other benefits.  
         [0029]     A highly reliable LED can also be created when the wavelength converting material is dispersed in alicyclic epoxy resin not containing phenyl radical or olefin resin. The wavelength converting material can remain similarly unaffected by humidity thanks to secure sealing.  
         [0030]     Thus, by radiating ultraviolet, blue or yellow light from the LED chip and converting the light from the LED chip to green and red light with the wavelength converting material, and radiating the resultant light, it is possible through mixing of these lights to obtain a white LED with excellent color reproducibility and reliability. Therefore, warm-looking white light containing light in the red range can be radiated, making the white LED applicable for use in various lighting equipment such as lighting sources for a variety of lighting instruments and LCD backlights (in place of conventional incandescent and other lamps). This makes it possible to obtain the same lighting effect as when a conventional incandescent or other conventional lamp is used, and at the same time obtaining a long-lasting light source with low power consumption and heat generation, among other benefits.  
         [0031]     According to a third aspect of the invention there is provided an LED that can include a pair of electrode members, two LED chips joined on top of a chip mounting portion disposed at an end of one of the pair of electrode members, each of the LED chips being electrically connected to both of the pair of electrode members, and a clear resin portion formed such that it surrounds the LED chips. The clear resin portion can include a wavelength converting material mixed therein, wherein one of the LED chips emits blue light, and another of the LED chips emits red light, wherein the wavelength converting material mixed in the clear resin portion converts at least part of the light from the one LED chip to green light that is longer in wavelength.  
         [0032]     In the above-described LED, the one of the LED chips that emits blue light can have a peak wavelength of about 440 to 480 nm, and the other of the LED chips that emits red light can have a peak wavelength of about 620 to 660 nm. The wavelength converting material can be configured to convert blue light from the one LED chip into green light that can have a peak wavelength of about 535 to 560 nm.  
         [0033]     Based on the above configuration, a drive voltage can be applied to two LED chips via a pair of electrode members, thus allowing the LED chips to emit blue light and red light. So, one of the LED chips emits blue light that can have a peak wavelength of about 420 to 480 nm, and another of the LED chips emits red light that can have a peak wavelength of about 620 to 660 nm. Then, blue and red light emitted from the LED chips can be externally emitted via a clear resin portion. At this time, part of the blue light emitted from the one of the LED chips can be directed to fall on a wavelength converting material within a clear resin portion, thus exciting the wavelength converting material and emitting green light that can have a peak wavelength of about 535 to 560 nm. Thus, blue light, red light, and green light can be mixed together, making it possible to obtain warm-looking white light having light characteristics in the red region. The white light can have excellent color reproducibility, as compared with a conventional white LED that emits bluish white light by mixing blue light and yellow fluorescence.  
         [0034]     Thus, by radiating blue and red light from the LED chips and converting the blue light from one of the LED chips into green light with the wavelength converting material, and radiating the resultant so-called primaries light, it is possible through mixing of these lights to obtain a white LED with excellent color reproducibility and reliability. Therefore, warm-looking white light containing light in the red range can be radiated, making the white LED applicable for use in various lighting equipment such as lighting sources for a variety of lighting instruments and LCD backlights (in place of conventional incandescent and other lamps). This makes it possible to obtain the same lighting effect as when a conventional incandescent or other conventional lamp is used, and at the same time obtaining a long-lasting light source with low power consumption and heat generation, among other benefits. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]     The above and other aspects, features and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:  
         [0036]      FIG. 1  is a schematic sectional view showing a configuration of a first embodiment of an LED made in accordance with the principles of the invention;  
         [0037]      FIG. 2  is a graph showing a spectrum distribution of white light produced by the LED of  FIG. 1 ;  
         [0038]      FIG. 3  is a schematic sectional view showing a configuration of a second embodiment of an LED made in accordance with the principles of the invention;  
         [0039]      FIG. 4  is a schematic sectional view showing a configuration of a third embodiment of an LED made in accordance with the principles of the invention;  
         [0040]      FIG. 5  is a graph showing a spectrum distribution of white light produced by the LED of  FIG. 4 ; and  
         [0041]      FIG. 6  is a schematic sectional view showing a configuration of a fourth embodiment of an LED made in accordance with the principles of the invention;  
         [0042]      FIG. 7  is a schematic sectional view showing a configuration of an example of a conventional shell-shaped white LED;  
         [0043]      FIG. 8  is a graph showing a spectrum distribution of white light produced by the LED of  FIG. 7 ; and  
         [0044]      FIG. 9  is a schematic sectional view showing a configuration of an example of a conventional surface-mount white LED. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0045]     A detailed description will be given below of embodiments of the invention with reference to FIGS.  1  to  6 . It is to be noted that while the embodiments described below are specific examples and thereby include various technical features, the scope of the invention is not limited to these embodiments.  
         [0046]      FIG. 1  shows a configuration of a first embodiment of an LED made in accordance with the principles of the invention. In  FIG. 1 , an LED  10  can be configured as a so-called shell-shaped LED and can include a pair of lead frames  11  and  12 , a blue LED chip  13  mounted on top of a chip mounting portion  11   a  formed on the upper end surface of the lead frame  11 , and a clear resin portion  14  formed soas to be adjacent to and/or surround the blue LED chip  13  on top of the chip mounting portion  11   a  of the lead frame  11 . A phosphor  14   a  can be mixed into the clear resin portion  14  and a lens portion  15  can be formed with a mold resin so as to be adjacent to and/or surround the upper ends of the lead frames  11  and  12 , the blue LED chip  13  and the clear resin portion  14 .  
         [0047]     The lead frames  11  and  12  can be formed out of a conductive material such as aluminum and can be provided with the chip mounting portion  11   a  and bonding portions  11   b  and  12   a  at the respective upper ends thereof. Whereas the other ends of the lead frames can be formed to extend downward to make up terminal portions  11   c  and  12   b.    
         [0048]     The blue LED chip  13  can be joined on top of the chip mounting portion  1   a  of the lead frame  11 , with two electrodes provided on the upper surface thereof electrically connected to the bonding portions  11   b  and  12   a  at the ends of the lead frames  11  and  12  through wire-bonding  17 .  
         [0049]     Here, the blue LED chip  13  can be configured, for example, as a GaN chip and can be designed such that when a drive voltage is applied via the lead frames  11  and  12 , light is emitted having a peak wavelength of about 450 to 470 nm.  
         [0050]     The clear resin portion  14  can be configured by combining, for example, epoxy resins hardened with acid anhydride or cation or olefin-based resins—resins into which the first phosphor  14   a  and a second phosphor  14   b  in fine particulate form can be mixed—and can be formed and hardened on top of the chip mounting portion  11   a  of the lead frame  11 .  
         [0051]     When blue light from the blue LED chip  13  falls on the clear resin portion  14 , the first phosphor  14   a  is excited, producing green light from the phosphor  14   a . At the same time, the second phosphor  14   b  is excited, producing red light from the phosphor  14   b . Here, the first phosphor  14   a  can include, for example, thiogallate phosphor and can be designed to produce green fluorescence having a peak wavelength of about 535 to 560 nm.  
         [0052]     On the other hand, the second phosphor  14   b  can include YAG phosphor doped with cerium, TAG phosphor doped with cerium or orthosilicate phosphor, and can be designed to produce red fluorescence having a peak wavelength of about 620 to 640 nm.  
         [0053]     The lens portion  15  can be made, for example, of clear epoxy resin, and can be formed such that it is adjacent to and/or surrounds the whole area near the upper ends of the lead frames  11  and  12  centering around the blue LED chip  13  and the clear resin portion  14 . The LED  10  can be configured as described above, and the blue LED chip  13  can produce blue light emission when a drive voltage is applied via the pair of lead frames  11  and  12 . Then, part of the light emitted from the LED chip  13  can fall on the phosphors  14   a  and  14   b  that are mixed into the clear resin portion  14 , thus exciting the phosphors  14   a  and  14   b  and producing green and red light. The green and red light can be mixed with blue light from the LED chip  13 , turning the subsequently emitted light into white light that can fall on the lens portion  15  through the clear resin portion  14  and be further emitted externally from the lens portion  15 .  
         [0054]     Thus, based on the surface-mount white LED  10 , blue light from the LED chip  13  can be mixed with green and red light produced by the phosphor layers  14   a  and  14   b , thus making it possible to obtain white light including light in the red range and light that is excellent in color reproducibility and, in particular, can approximate the light color produced by a typical electric bulb. A spectrum distribution of the white light is shown in the graph of  FIG. 2 .  
         [0055]     The phosphors  14   a  and  14   b  can also be securely sealed by the clear resin, thus making it possible to obtain a highly reliable LED  10  that is relatively resistant to humidity.  
         [0056]      FIG. 3  shows a configuration of a second embodiment of an LED. In  FIG. 3 , an LED  20  is configured as a so-called surface-mount LED and can include a chip substrate  21 , a blue LED chip  22  mounted on top of the chip substrate  21 , a frame-shaped member  23  formed on top of the chip substrate  21  such that it is adjacent to and/or surrounds the blue LED chip  22 . A clear resin portion  24  can be charged into a recessed portion  23   a  of the frame-shaped member  23  to cover the blue LED chip  22 .  
         [0057]     It is to be noted that the blue LED chip  22  and the clear resin portion  24  can have the same configuration as in the LED chip  13 , and that the clear resin portion  14  of the LED  10  shown in  FIG. 1  can be omitted.  
         [0058]     The chip substrate  21  can be made of a heat-resistant resin and include a flat copper clad wired board. A chip mounting land  21   a , and an electrode land  21   b  can be provided on a surface of the chip substrate  21 . Surface-mount terminal portions  21   c  and  21   d  can be configured such that they extend around from these lands onto the lower surface via both end edges of the chip substrate  21 .  
         [0059]     The blue LED chip  22  can be joined on top of the chip mounting land  21   a  of the chip substrate  21 , with the surface of the blue LED chip  22  electrically connected to the chip mounting land  21   a  and the adjacent electrode land  21   b  through wire-bonding  25 . The frame-shaped member  23 , can also be formed on top of the chip substrate  21  with a heat-resistant resin, and can be provided with a recessed portion  23   a  (for example, a portion in the form of an inverted truncated cone) so as to be adjacent to and/or surround the blue LED chip  22 . It is to be noted that the inner surface of the recessed portion  23   a  can be configured as a reflecting surface.  
         [0060]     Based on the white LED  20  thus configured, the blue LED chip  22  can emit blue light when a drive voltage is applied via the surface-mount terminals  21   c  and  21   d . Then, part of blue light emitted from the LED chip  22  can be directed to fall on phosphors  24   a  and  24   b  that are mixed into the clear resin portion  24 , thus exciting the phosphors  24   a  and  24   b  and producing green and red light. The green and red light can then mix with blue light from the LED chip  22 , turning the light into white light. The white light can then be directed to pass through the clear resin portion  24 . Part of the white light can be directly omitted while another part is reflected by the inner surface of the recessed portion  23   a  of the frame-shaped member  23 , thus being externally emitted.  
         [0061]     The above-described LED  20  can function similar to the LED  10  shown in  FIG. 1 , mixing blue light emitted from the LED chip  22  with green and red light produced by the phosphor layers  24   a  and  24   b  to produce white light. The white light can include light in the red range that is excellent in color reproducibility and, in particular, can have a color similar to the color of light for a conventional electric bulb.  
         [0062]     The phosphors  24   a  and  24   b  can be securely sealed by the clear resin, thus making it possible for the LED  20  to be highly reliable and relatively resistant to humidity.  
         [0063]     In the above-described embodiments, the LED chip can have a peak wavelength of about 450 to 470 nm. However, the invention is not limited thereto, and the range can be broadened such that the LED chip has a peak wavelength, for example, of about 440 to 480 nm. The LED chip is also not limited to a blue LED chip and may be an ultraviolet or green LED chip.  
         [0064]     On the other hand, while in the above-described embodiments, epoxy resins hardened with acid anhydride or cation or olefin-based resins can be combined for use as the clear resin to make up the clear resin portions  14  and  24 , the invention is not limited thereto. The phosphors  14   a ,  14   b ,  24   a  and  24   b  can be dispersed and securely sealed, and alicyclic epoxy resin not containing phenyl radical or olefin resin, for example, may also be used. Thus, it is possible to provide, through a simple configuration, an LED capable of emitting warm-looking white light.  
         [0065]      FIG. 4  shows a configuration of a third embodiment of an LED made in accordance with the principles of the invention. In  FIG. 4 , an LED  30  can be configured as a so-called shell-shaped LED and can include a pair of lead frames  31  and  32 , a blue LED chip  33 , and a red LED chip  34  mounted adjacent each other on top of a chip mounting portion  31   a  formed on the upper end surface of the lead frame  31 , and a clear resin portion  35  formed so as to be adjacent to and/or surround the blue LED chip  33  and the red LED chip  34  on top of the chip mounting portion  31   a  of the lead frame  31 . A phosphor  35   a  can be mixed into the clear resin portion  35  and a lens portion  36  can be formed with a mold resin so as to be adjacent to and/or surround the upper ends of the lead frames  31  and  32 , the blue LED chip  33 , the red LED chip  34  and the clear resin portion  35 .  
         [0066]     The lead frames  31  and  32  can be formed out of a conductive material such as aluminum and can be provided with the chip mounting portion  31   a  and bonding portions  31   b  and  32   a  at the respective upper ends thereof. Whereas the other ends of the lead frames can be formed to extend downward to make up terminal portions  31   c  and  32   b.    
         [0067]     The blue LED chip  33  can be joined on top of the chip mounting portion  31   a  of the lead frame  31 , with two electrodes provided on the upper surface thereof electrically connected to the bonding portions  31   b  and  32   a  at the ends of the lead frames  31  and  32  through wire bonding  37 .  
         [0068]     Here, the blue LED chip  33  can be configured, for example, as a GaN chip and can be designed such that when a drive voltage is applied via the lead frames  31  and  32 , light is emitted having a peak wavelength of about 450 to 470 nm. Here the blue LED chip  33  also can be configured as an InGaN chip.  
         [0069]     The red LED chip  34  can be die-bonded on top of the chip mounting portion  31   a  of the lead frame  31 , with an electrode provided on the upper surface thereof electrically connected to the bonding portion  32   a  at the ends of the lead frame  32  through wire-bonding  37 .  
         [0070]     Here, the red LED chip  34  can be configured, for example, as an AlInGaP chip and can be designed such that when a drive voltage is applied via the lead frames  31  and  32 , light is emitted having a peak wavelength of about 620 to 660 nm. Here, the red LED chip  34  also can be configured as an AlGaAs chip.  
         [0071]     The clear resin portion  35  can be configured by combining, for example, epoxy resins hardened with acid anhydride or cation or olefin-based resins—resins into which the phosphor  35   a  in fine particulate form can be mixed—and can be formed and hardened on top of the chip mounting portion  31   a  of the lead frame  31 .  
         [0072]     When blue light from the blue LED chip  33  falls on the clear resin portion  35 , the phosphor  35   a  can be excited producing green light from the phosphor  35   a . Here the phosphor  35   a  can include, for example, thiogallate phosphor and can be designed to produce green fluorescence having a peak wavelength of about 535 to 560 nm.  
         [0073]     The lens potion  36  can be made, for example, of clear epoxy resin and can be formed such that it is adjacent to and/or surrounds the whole area near the upper ends of the lead frames  31  and  32  centering around the blue LED chip  33 , the red LED chip  34  and the clear resin portion  35 .  
         [0074]     The LED  30  can be configured as described above, and the blue LED chip  33  and the red LED chip  34  can produce blue and red light emission when a drive voltage is applied via the pair of lead frames  31  and  32 . Then, part of the blue light emitted from the blue LED chip  33  can fall on the phosphor  34   a  that is mixed into the clear resin portion  35 , thus exciting the phosphor  35   a  and producing green light. The green light can be mixed with blue and red lights from the LED chips  33  and  34 , turning the subsequently emitted light into white light that can fall on the lens portion  36  through the clear resin portion  35  and be further emitted externally from the lens portion  36 .  
         [0075]     Thus, based on the surface-mount white LED  30 , blue and red light from the LED chips  33  and  34  can be mixed with green light produced by the phosphor layer  35   a , thus making it possible to obtain white light including light in the red range and light that is excellent in color reproducibility and, in particular, can approximate the light color produced by a typical electric bulb. A spectrum distribution of the white light is shown in the graph of  FIG. 5 .  
         [0076]     The phosphor  35   a  can also be securely sealed by the clear resin, thus making it possible to obtain a highly reliable LED  30  that is relatively resistant to humidity.  
         [0077]      FIG. 6  shows a configuration of a fourth embodiment of an LED. In  FIG. 6 , an LED  40  can be configured as a so-called surface mount LED and can include a chip substrate  41 , a blue LED chip  42 , and a red LED chip  43  mounted on top of the chip substrate  41 , a frame-shaped member  44  formed on top of the chip substrate  41  such that it is adjacent to and/or surrounds the blue LED chip  42  and the red LED chip  43 . A clear resin portion  45  can be charged into a recessed portion  44   a  of the frame-shaped member  44  to cover the blue LED chip  42  and the red LED chip  43 .  
         [0078]     It is to be noted that the blue LED chip  42 , the red LED chip  43  and the clear resin portion  45  can have the same configuration as in the LED chip  33  and  34 , and that the clear resin portion  35  of the LED  30  shown in  FIG. 4  can be omitted.  
         [0079]     The chip substrate  41  can be made of a heat-resistant resin and include a flat copper clad wired board. A chip mounting land  41   a , and an electrode land  41   b  can be provided on a surface of the chip substrate  41 . Surface-mount terminal portions  41   c  and  41   d  can be configured such that they extend around from these lands onto the lower surface via both end edges of the chip substrate  41 .  
         [0080]     The blue LED chip  42  and the red LED chip  43  can be joined on top of the chip mounting land  41   a  of the chip substrate  41 , with the surface of the blue LED chip  42  electrically connected to the chip mounting land  41   a  and the adjacent electrode land  41   b  through wire-bonding  46 . The surface of the red LED chip  43  can be electrically connected to the electrode  41   b  through wire-bonding  46 .  
         [0081]     The frame-shaped member  44 , can also be formed on top of the chip substrate  41  with a heat-resistant resin, and can be provided with a recessed portion  44   a  (for example, a portion in the form of an inverted truncated cone) so as to be adjacent to and/or surround the blue LED chip  42  and the red LED chip  43 . It is to be noted that the inner surface of the recessed portion  44   a  can be configured as a reflecting surface.  
         [0082]     Based on the white LED  40  thus configured, the blue LED chip  42  and the red LED chip  43  can emit blue and red light when a drive voltage is applied via the surface-mount terminals  41   c  and  41   d . Then, part of the blue light emitted from the blue LED chip  42  can be directed to fall on phosphor  45   a  that is mixed into the clear resin portion  45 , thus exciting the phosphor  45   a  and producing green light. The green light can then mix with blue and red light from the LED chip  42  and  43 , turning the light into white light. The white light can then be directed to pass through the clear resin portion  45 . Part of the white light can be directly omitted while another part is reflected by the inner surface of the recessed portion  44   a  of the frame-shaped member  44 , thus being externally emitted.  
         [0083]     The above-described LED  40  can function similar to the LED  30  shown in  FIG. 4 , mixing blue and red light emitted from the LED chips  42  and  43  with green light produced by the phosphor layer  45   a  to produce white light. The white light can include light in the red range that is excellent in color reproducibility and, in particular, can have a color similar to the color of light for a conventional electric bulb.  
         [0084]     In the above-described embodiments, the LED chip can have a peak wavelength of about 450 to 470 nm. However, the invention is not limited thereto, and the range can be broadened such that the LED chip has a peak wavelength, for example, of about 440 to 480 nm. The LED chip is also not limited to a blue LED chip and may be an ultraviolet or green LED chip.  
         [0085]     On the other hand, while in the above-described embodiments, epoxy resins hardened with acid anhydride or cation or olefin-based resins can be combined for use as the clear resin to make up the clear resin portions  14  and  24 , the invention is not limited thereto. The phosphors  14   a ,  14   b ,  24   a  and  24   b  can be dispersed and securely sealed, and alicyclic epoxy resin not containing phenyl radical or olefin resin, for example, may also be used. Thus, it is possible to provide through a simple configuration, an LED capable of emitting warm-looking white light.  
         [0086]     The means for converting light as described above includes a first phosphor and a second phosphor. The first and second phosphors can include thiogallate phosphor as the first phosphor and at least one of rare-earth-activated aluminate and rare-earth-activated orthosilicate as the second phosphor. However, it should be understood that it is within the spirit and scope of the invention for the first and second phosphors to include, comprise, or consist of other materials that are well known to convert light into green and/or red wavelength light. In addition, the wavelength converting material is described above as being dispersed in alicyclic epoxy resin not containing phenyl radical or olefin-based resin. However, other epoxy resins, plastics, crystalline structures and materials can be used to carry the wavelength converting material. Furthermore, while a shell type LED and a surface mount LED are described above, there are other types of LED configurations in which the principles of the invention can be applied.  
         [0087]     While illustrative embodiments of the invention have been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.

Technology Classification (CPC): 7