JP2010045248A - Light-emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To emit visible light only from a side surface of an LED. <P>SOLUTION: A metal pad (not shown) is provided on an upper surface of a circuit board 2 of an insulating BT resin etc., constituting an LED 1 with a wide viewing angle, and an LED chip 3 for emitting ultraviolet light is die-bonded on the pad. Further, a pair of wiring circuits (not shown) are provided on a surface of the circuit board 2, and wire-bonding connections from an electrode of the LED chip 3 to the wiring circuits are made by gold wires 4. On the circuit board 2, a frame 5 in a square cylinder shape or circular cylinder shape is fixed enclosing a second bonding area. The frame 5 having an equal thickness L is formed of an epoxy resin or silicone resin containing a tricolor phosphor excited in the ultraviolet range. The frame 5 is filled with a sealing resin 6 made of a translucent resin such as an epoxy resin and a silicone resin. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting diode having a wide viewing angle used in a field such as key illumination of a cellular phone.

  An example of a conventional general light emitting diode (hereinafter abbreviated as LED) will be described. FIG. 5 is a plan view showing an example of a conventional LED, and FIG. 6 is a cross-sectional view showing the XX cross section of FIG. 5 and 6, the LED 51 is of a surface mount type in which an LED chip 53 is die-bonded on the circuit board 2 and wired with a gold wire 4 and sealed with a sealing resin 56 containing a phosphor. The distances A, B and C between the LED chip and the outer wall are generally different from each other.

In addition, since LED has high directivity and a narrow viewing angle, it has a drawback that visibility from the front is good but visibility from the side is poor. Therefore, an LED having a wide viewing angle is required for application to a field such as key illumination of a mobile phone. As an LED required in such a field, an LED chip is mounted on a circuit board and a reflective material layer is formed on the upper surface of the sealing resin so that the intensity of front emission is controlled and taken out in the lateral direction. (For example, refer to Patent Document 1).
JP 2004-304041 (FIGS. 1-5, pages 3-4)

  However, when a reflective surface is formed on the upper surface of a conventional general LED, the path length of the light transmitted through the phosphor layer (wavelength conversion layer) differs depending on the emission direction. There is a problem that the length varies depending on the emission direction. For example, when the LED chip 53 emits blue light and the sealing resin 56 includes a YAG phosphor and is adjusted to emit white light upward (C direction), the path The light emitted in the A direction whose length is shorter than the C direction is blue, and the light emitted in the B direction whose path length is longer than the C direction is yellow. Further, when the LED chip 53 emits ultraviolet light and the sealing resin 56 includes a three-color phosphor, the LED chip 53 is adjusted to emit white light upward (C direction). The white light emitted in the lateral direction is not a problem in the A direction, but the path length is darker in the B direction, which is longer than the C direction.

  The present invention has been made to solve such a conventional problem, and an object thereof is to provide an LED having a wide viewing angle from which uniform visible light can be efficiently extracted from the side surface.

  The means of the present invention for achieving the above-described object is a light emitting diode in which an LED chip is mounted on a circuit board and the LED chip is sealed with a light-transmitting resin having different vertical and horizontal lengths. The chip emits ultraviolet light, and a frame body of equal thickness formed of a resin containing a phosphor excited in the ultraviolet region is disposed on the circuit board so as to surround the translucent resin. It is characterized by.

  The phosphor is a three-color phosphor.

  Further, the upper surface of the translucent resin is covered with a reflection sheet.

  Another means of the present invention for achieving the above-described object is to provide a light-emitting diode in which an LED chip is mounted on a circuit board, and the LED chip is sealed with a translucent resin having different vertical and horizontal lengths. The LED chip emits blue light, and on the circuit board is disposed a frame body of equal thickness formed of a resin containing a YAG phosphor so as to surround the translucent resin. The upper surface of the translucent resin is covered with a reflection sheet.

  According to the present invention, an LED chip is mounted on a circuit board, and the LED chip is sealed with a light-transmitting resin having different outer and vertical lengths. The LED chip emits ultraviolet light. The chip is a chip, and a frame body of equal thickness formed of a resin containing a phosphor excited in the ultraviolet region is disposed on the circuit board so as to surround the translucent resin. Because it is out of the area, it is invisible to the human eye. On the other hand, the light emitted from the side surface is excited by the phosphor frame and becomes visible light, which becomes visible to human eyes. Therefore, when this LED is used in a scene such as key illumination of a cellular phone, the viewing angle is widened and the display visibility is improved.

  In addition, since the phosphor is a three-color phosphor, by changing the blending ratio of the phosphor, it is possible to produce not only white but also other colors with high color rendering properties. can get.

  In addition, since the upper surface of the translucent resin is covered with the reflection sheet, the light directed toward the upper surface is reflected and guided toward the side surface, and more efficiently emits light from the side surface to obtain an LED having a wide viewing angle. .

  Further, in a light emitting diode in which an LED chip is mounted on a circuit board and the LED chip is sealed with a light-transmitting resin having different external shapes in length and width, the LED chip emits ultraviolet light, On the circuit board, a frame with an equal thickness formed of a resin containing a phosphor excited in the ultraviolet region is disposed so as to surround the translucent resin, so that no light is emitted from the upper surface, and white is seen from the side. Light can be extracted. Therefore, an LED having a wide viewing angle can be obtained.

  Hereinafter, a wide viewing angle LED which is the best embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view showing a wide viewing angle LED according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the XX cross section of FIG.

  First, the configuration of the wide viewing angle LED according to the first embodiment of the present invention will be described. 1 and 2, a metal pad (not shown) is provided on the upper surface of a circuit board 2 such as an insulating BT resin that constitutes the LED 1 having a wide viewing angle, and an LED that emits ultraviolet light on the pad. Chip 3 is die-bonded. There is a pair of wiring circuits (not shown) on the surface of the circuit board 2, and the wires from the electrodes of the LED chip 3 to the wiring circuits are connected by wire bonding with gold wires 4. A frame 5 having a rectangular outer shape is fixed on the circuit board 2 so as to surround the second bonding region. The frame 5 having an equal thickness L is formed of an epoxy resin or a silicone resin containing a phosphor that is excited in the ultraviolet region. The inside of the frame 5 is filled with a sealing resin 6 made of a translucent resin such as an epoxy resin or a silicone resin having external shapes with different vertical and horizontal lengths.

  Here, the phosphor excited in the ultraviolet region includes, for example, a three-color phosphor, and is a phosphor that emits three colors of red, blue, and green by excitation of ultraviolet light. The three colors are mixed to emit white light. In addition to the three-color phosphor, the phosphor excited in the ultraviolet region may be a multicolor phosphor containing orange or yellow-green in addition to the three colors in order to improve color rendering. Further, pseudo white light can be emitted by phosphors emitting blue and yellow or red and green.

  Next, the operation of the first embodiment will be described. When a signal current is applied to the wiring circuit, it enters the LED chip 3 via the gold wire 4, and the LED chip 3 emits ultraviolet light. The light emitted toward the front of the LED 1 (upper side in FIG. 2) is ultraviolet light and is not visible to human eyes. On the other hand, the ultraviolet light emitted from the LED chip 3 toward the side surface of the LED 1 is converted into white light by exciting the phosphor when passing through the frame body 5 to be converted into white light. Emitted.

  Next, the effect of the first embodiment of the present invention will be described. The light emitted from the LED chip 3 is not visible because it is ultraviolet light in the front direction of the LED 1, and the light directed toward the side surface of the LED 1 passes through the frame 5 and becomes visible to the human eye. At this time, since the sealing resin 6 is translucent, the transmittance is better than that of the resin containing the phosphor and the light is brighter. Since both the light emitted from the short side of the frame 5 and the light emitted from the long side have the same thickness L, they become uniform visible light having the same chromaticity. Therefore, when the LED 1 is applied to key illumination of a mobile phone, the visibility is improved.

  Next, the configuration of the LED according to the second embodiment of the present invention will be described. FIG. 3 is a plan view of an LED according to a second embodiment of the present invention, and FIG. 4 is a cross-sectional view showing the XX cross section of FIG. In FIG. 3, a reflection sheet 7 made of an aluminum sheet or a sheet having silver deposited on the lower surface covers the upper surface of the translucent resin 6. Since other configurations are the same as those of the LED 1 according to the first embodiment, the same components are denoted by the same reference numerals and names, and detailed description thereof is omitted.

  Next, operations and effects of the second embodiment will be described. The ultraviolet light emitted from the LED chip 3 in the front direction of the LED 11 has a high reflectance on the lower surface of the reflecting sheet 7 and therefore does not travel toward the upper surface, but reflects on the lower surface of the sheet and travels toward the side surface of the LED 11. The ultraviolet light directed toward the side surface from the beginning is reflected and overlapped with the ultraviolet light directed toward the side surface to increase the amount of light, and when passing through the frame 5, the phosphor is excited to be converted into visible light and emitted. Therefore, visible light can be emitted from the side surface of the LED 11 more effectively than the LED 1. Therefore, the effect which stands out more than LED1 can be expected.

  In the first embodiment described above, mounting of the LED chip is not limited to wire bonding, but may be connection by bumps.

  In the second embodiment described above, the LED chip 3 can be replaced with one that emits blue light, and the frame 5 can be replaced with a resin containing a YAG phosphor. In this case, the same effect as that of the second embodiment can be expected.

It is a top view which shows the light emitting diode which is 1st embodiment of this invention. It is a longitudinal cross-sectional view which shows the XX cross section of FIG. It is a top view which shows the light emitting diode which is 2nd embodiment of this invention. It is a longitudinal cross-sectional view which shows the XX cross section of FIG. It is a top view which shows the conventional light emitting diode. It is a longitudinal cross-sectional view which shows the XX cross section of FIG.

Explanation of symbols

1,11 LED
2 Circuit board 3 LED chip 5 Frame 6 Sealing resin 7 Reflective sheet

Claims (4)

  In a light-emitting diode in which an LED chip is mounted on a circuit board and the LED chip is sealed with a light-transmitting resin having different external shapes in length and width, the LED chip emits ultraviolet light, and the circuit board A light emitting diode characterized in that a frame body of equal thickness formed of a resin containing a phosphor excited in the ultraviolet region is disposed so as to surround the translucent resin.   2. The light emitting diode according to claim 1, wherein the phosphor is a three-color phosphor.   The light emitting diode according to claim 1 or 2, wherein an upper surface of the translucent resin is covered with a reflection sheet.   In a light emitting diode in which an LED chip is mounted on a circuit board and the LED chip is sealed with a light-transmitting resin having different external shapes in length and width, the LED chip emits blue light, and the circuit board A frame having an equal thickness formed of a resin containing a YAG phosphor is disposed on the top to surround the translucent resin, and the upper surface of the translucent resin is covered with a reflective sheet. Light emitting diode.

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