JP2007266314A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To radiate light to the outside with fixed intensity by individually adjusting the intensity of light from each LED, and to perform miniaturization. <P>SOLUTION: An emitter 1 has a red LED 10 for radiating red light, a green LED 11 for radiating green light, and a blue LED 12 for radiating blue light, thus generating white light. A base member 2 comprises: an LED package 22 where respective LEDs 10-12 are packaged; and walls 23-26 provided around a region where respective LEDs 10-12 are packaged in the LED package 22. Each of a plurality of light detectors 50-55 is provided at the walls 23-26, thus detecting the intensity of light radiated from mutually different LEDs 10-12. A control unit 6 controls current supplied to respective LEDs 10-12 so that the intensity of color light detected by respective light detectors 50-55 becomes the intensity of predetermined color light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device that emits light from a plurality of LEDs.

  Conventionally, as shown in FIG. 2, this type of light emitting device (first conventional light emitting device) includes a plurality of LEDs 80 to 82 that emit light having different wavelengths from each other in a base member 83, and these LEDs 80 to 82. The mixed color light is generated by the colored light emitted from the light and emitted to the outside. The intensity of each colored light emitted from each of the LEDs 80 to 82 rapidly decreases when a predetermined radiation time elapses even if the supplied current is constant from the beginning. For this reason, the first conventional light emitting device includes one light detection unit 84 that detects the intensity of the mixed color light, and the LEDs 80 to 80 are arranged so that the intensity of the colored light detected by the light detection unit 84 is constant. The current supplied to 82 is controlled. Here, the intensity of the colored light from each of the LEDs 80 to 82 has a different tendency with respect to the emission time.

  However, in the first conventional light emitting device, only the intensity of the mixed color light can be detected by the light detection unit 84. Therefore, the first conventional light emitting device has a problem that it is difficult to accurately control the current supplied to the LEDs 80 to 82 because the intensity of the colored light from the LEDs 80 to 82 is unknown. .

As a second conventional light emitting device that solves the above problem, for example, in Patent Document 1, the light detection element measures the wavelength intensity distribution of light in each color region, and the light emission intensity and light emission intensity ratio of each color are set to a predetermined value. An illumination device that feedback-controls the operation of the drive circuit of each LED so as to keep the value is disclosed.
JP 2002-344031 A (pages 4 to 6 and FIG. 3B)

  However, as shown in FIG. 2, the first conventional light emitting device has a problem that it becomes large by securing the installation space for the light detection unit 84 separately from the LEDs 80 to 82. In addition, the second conventional light emitting device has a problem that it is similarly large.

  The present invention has been made in view of the above points, and an object of the present invention is to individually adjust the intensity of light from each LED to radiate light having a constant intensity to the outside and to reduce the size. An object of the present invention is to provide a light-emitting device that can be realized.

  According to the first aspect of the present invention, a plurality of LEDs each emitting light when supplied with current, an LED mounting portion on which the plurality of LEDs are mounted, and the plurality of LEDs among the LED mounting portions A base member having a wall portion provided around a region where each is mounted, and a plurality of light detection portions each provided on the wall portion for detecting the intensity of light emitted from the different LEDs. A control unit that controls the current supplied to each of the plurality of LEDs so that the intensity of the light detected by each of the plurality of light detection units becomes a predetermined light intensity. It is characterized by.

  According to this configuration, even if the change in the intensity of light with respect to the emission time of each LED is different, the intensity of light from each LED can be individually adjusted to emit light with a constant intensity to the outside, Since each light detection part is provided in a wall part, it is not necessary to ensure the installation space of each light detection part separately, and size reduction of a light-emitting device can be achieved.

  According to the present invention, it is possible to individually adjust the intensity of light from each LED to radiate light having a constant intensity to the outside and to reduce the size.

(Embodiment 1)
Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating the light emitting device of the first embodiment.

  First, the basic configuration of the first embodiment will be described. The light-emitting device of Embodiment 1 radiates white light to the outside. As shown in FIG. 1, the light-emitting unit 1, the base member 2, the current supply unit 3, the protective cover 4, and a plurality of lights Detection units 50 to 55 and a control unit 6 are provided.

  The light emitting unit 1 includes a red LED (red light emitting diode) 10, a green LED (green light emitting diode) 11, and a blue LED (blue light emitting diode) 12. The red LED 10 is electrically connected to the control unit 6, and emits red light when current is supplied from the current supply unit 3 through the control unit 6. Similarly, the green LED 11 is connected to the control unit 6, and emits green light when current is supplied from the current supply unit 3 via the control unit 6. The blue LED 12 is connected to the control unit 6, and emits blue light when current is supplied from the current supply unit 3 via the control unit 6. The light emitting unit 1 generates white light by combining the red light, green light, and blue light. Here, the intensity of each colored light emitted from the red LED 10, the green LED 11, and the blue LED 12 rapidly decreases after a predetermined emission time even if the supplied current is constant from the beginning. The degree of intensity reduction of the colored light is different for the red LED 10, the green LED 11, and the blue LED 12.

  The base member 2 includes a first mounting board 20 and a second mounting board 21. The first mounting substrate 20 is an inexpensive and conductive n-type silicon (Si) substrate having recesses 200 to 202 formed on the upper surface by etching. By using silicon as the first mounting substrate 20 as described above, the cost can be reduced. The red LED 10 is mounted on the bottom surface of the recess 200, the green LED 11 is mounted on the bottom surface of the recess 201, and the blue LED 12 is mounted on the bottom surface of the recess 202. A pair of through holes 203... Are formed at positions where the red LED 10, the green LED 11 and the blue LED 12 are mounted on the first mounting substrate 20, and the through holes 204, around the recesses 200 and 202. 204 is formed. An insulating region 205 that is thermally oxidized to silicon oxide is formed on the lower surface of the first mounting substrate and around each of the through holes 203 and 204. In addition, the first mounting substrate 20 includes a conductive portion 206 so as to close the through holes 203 and 204. The conductive portion 206 is a conductive material such as copper, gold, aluminum, or solder. Further, the first mounting substrate 20 includes an upper surface electrode 207 on the upper opening surface of each through-hole 203 and 204, and a lower surface electrode 208 on the lower opening surface. The upper surface electrode 207 and the lower surface electrode 208 are conductive materials such as copper, gold, aluminum, or solder, and are electrically connected via the conductive portion 206. These upper surface electrode 207 and lower surface electrode 208 are formed by removing a part of the conductive material laminated on the recesses 200 to 202 and the lower surface by etching. The second mounting substrate 21 is an inexpensive and conductive n-type silicon substrate, and has an opening 210 formed by etching. By using silicon as the second mounting substrate 21 as described above, the cost can be reduced.

  The base member 2 includes an LED mounting portion 22 on which the red LED 10, the green LED 11, and the blue LED 12 are mounted, and the LED mounting portion 22 by bonding the first mounting substrate 20 and the second mounting substrate 21 together. And wall portions 23 to 26 provided so as to protrude upward.

  The current supply unit 3 is an integrated circuit (IC) formed on the wall 23 by repeating masking and impurity implantation on the lower surface of the second mounting substrate 21. The current supply unit 3 is electrically connected individually to each of the red LED 10, the green LED 11, and the blue LED 12, and further electrically connected to the control unit 6. The current supply unit 3 supplies current to each of the red LED 10, the green LED 11, and the blue LED 12 by pulse width modulation (PWM) based on the adjustment signal from the control unit 6. At this time, the current supply unit 3 can change the pulse width within a predetermined range. Specifically, the pulse width is widened to increase the intensity of the colored light, and the pulse width is narrowed to reduce the intensity of the colored light. As a result, the pulse width can be changed and the current supplied to the red LED 10, the green LED 11 and the blue LED 12 can be changed, and the current load can be increased in the red LED 10, the green LED 11 and the blue LED 12. Can be prevented.

  The protective cover 4 is formed of a transparent material such as silicone resin, acrylic resin, epoxy resin, or glass, for example, and includes a plate-like base portion 40 and a plurality of hemispherical portions 41 provided on the upper surface of the base portion 40. A part of the lower surface of the base portion 40 is bonded to the upper surfaces of the wall portions 23 and 24 of the base member 2 to seal the space region 7 in which the red LED 10, the green LED 11 and the blue LED 12 are mounted together with the base member 2 and the spacer 4. The plurality of hemispherical portions 41 are located above the red LED 10, the green LED 11, and the blue LED 12 when the base portion 40 seals the space region 7. The protective cover 4 transmits the red light from the red LED 10, the green light from the green LED 11, and the blue light from the blue LED 12 to radiate outside (upward).

  Each of the plurality of light detection units 50 to 55 is a pn junction photodiode. The light detection unit 50 is provided on the right side of the wall 25. The light detection part 51 is provided on the left side of the wall part 26, the light detection part 52 is provided on the right side of the wall part 24, the light detection part 53 is provided on the left side of the wall part 25, and the light detection part 54 is provided on the wall part 26. The light detection part 55 is provided on the left side of the wall part 23. The p-type region of each of the light detection units 50 to 55 is subjected to masking and p-type impurity implantation with respect to the first mounting substrate 20, thereby causing a predetermined amount from a part of the upper surface and side surfaces of the wall portions 23 to 26. Formed to depth. The n-type region is formed from the upper surface of the walls 23 to 26 to a predetermined depth by performing masking and n-type impurity implantation on the p-type region. The light detection parts 50-55 are provided in the wall parts 23-26 as mentioned above.

  Of these light detection units 50 to 55, the light detection units 50 and 51 detect the intensity of red light emitted from the red LED 10. Similarly, the light detection units 52 and 53 detect the intensity of the green light emitted from the green LED 11. The light detection units 54 and 55 detect the intensity of the blue light emitted from the blue LED 12. Each of the light detection units 50 to 55 is electrically connected to the control unit 6 and transmits the detected intensity of the colored light to the control unit 6.

  The controller 6 is an integrated circuit formed on the wall 24 by repeating masking and impurity implantation on the lower surface of the second mounting substrate 21. The control unit 6 includes a storage unit (not shown), a comparison unit (not shown), and a correction unit (not shown). The storage unit is connected to the comparison unit and stores in advance a reference value of intensity for each of red light, green light, and blue light. The reference value of the intensity is, for example, the average value of the intensity in the initial state of the LEDs of the same lot as each of the LEDs 10 to 12. Thereby, the value which reduced the dispersion | variation of each LED can be used as a reference value. Note that, instead of the average value of the intensity of LEDs of the same lot, the intensity of light from each of the LEDs 10 to 12 may be detected as an initial value at the time of manufacture, and this initial value may be used as a reference value.

  The comparison unit (not shown) is connected to each of the light detection units 50 to 55 and further connected to a storage unit and an adjustment unit (not shown). When a current is supplied to the red LED 10, the green LED 11, and the blue LED 12, the comparison unit inputs the intensity of the colored light detected by each of the light detection units 50 to 55 as a detection value. After inputting the detection value, the comparison unit compares whether or not the detection value is equal to or substantially equal to the reference value stored in the storage unit, and sends a comparison signal based on the comparison result to the adjustment unit. Output. In the comparison, the detected value is equal to or nearly equal to the reference value includes not only the case where the detected value matches the reference value but also the case where the detected value is within 10% of the reference value. Thereby, it is possible to remove the influence of the variation in the detected value.

  The adjustment unit (not shown) is connected to a comparison unit (not shown), and inputs a comparison signal for each color light from the comparison unit. When the detected value is different from the reference value, the adjusting unit adjusts the current supplied to the corresponding LEDs 10 to 12 so that the detected value is equal to or substantially equal to the reference value. Specifically, when the detected value is smaller than the reference value, an adjustment signal is output to the current supply unit 3 so that the pulse width of the current supplied to the corresponding LEDs 10 to 12 becomes wide.

  As described above, according to the first embodiment, the intensity of the red light from the red LED 10 and the intensity of the green light from the green LED 11 are different even if the intensity changes of the colored light with respect to the emission times of the red LED 10, the green LED 11, and the blue LED 12 are different. In addition, the intensity of blue light from the blue LED 12 can be individually adjusted to radiate white light (mixed color light) with a constant intensity to the outside. Moreover, since each light detection part 50-55 is provided in the wall parts 23-26 of the base member 2, it is not necessary to ensure the installation space of each light detection part 50-55 separately, and size reduction of a light-emitting device is achieved. Can be planned.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the light emitting device of the second embodiment includes a light emitting unit 1, a current supply unit 3, a protective cover 4, a plurality of light detection units 50 to 55, and a control unit 6. The light-emitting device is provided in the same manner as the light-emitting device, but has the following characteristic portions that are not included in the light-emitting device of Embodiment 1.

  Unlike the base member of the first embodiment, the base member 2 of the second embodiment is formed of silicon carbide (SiC). The silicon carbide base member 2 has conductivity similar to the silicon base member, and is superior in heat resistance to the silicon base member. The base member 2 of the second embodiment is the same as the base member of the first embodiment except for the points described above.

  As described above, according to the second embodiment, since silicon carbide is used as the base member 2, the heat resistance can be improved.

(Embodiment 3)
Embodiment 3 of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the light emitting device of Embodiment 3 includes a light emitting unit 1, a base member 2, a current supply unit 3, a protective cover 4, a plurality of light detection units 50 to 55, and a control unit 6. Is provided in the same manner as the light-emitting device of Embodiment 1, but has the following characteristic portions that are not included in the light-emitting device of Embodiment 1.

  Unlike the light emitting device of the first embodiment, the light emitting device of the third embodiment seals the space region 7 with a sealing material. The sealing material is formed of a transparent resin such as a silicone resin, an epoxy resin, or an acrylic resin, and has translucency and elasticity. Among these, silicone resins have higher heat resistance and thermal conductivity than epoxy resins and acrylic resins, so that they are less likely to be deformed even at high temperatures, and the heat dissipation effect for heat from the light emitting portion 1 can be enhanced. The sealing material is formed by injecting a liquid transparent resin into the space region 7 and thermosetting it. The light emitting device of Embodiment 3 is the same as the light emitting device of Embodiment 1 except for the points described above.

  As described above, according to the third embodiment, since the space region 7 is sealed with the sealing material, the heat dissipation effect in the space region 7 can be enhanced.

  As a modification of the first to third embodiments, a configuration in which a spacer is provided between the base member and the protective cover may be used. The spacer is an aluminum thin film, for example, and is formed on the upper surface of the base member by a sputtering method. Even if it is such a structure, there exists an effect similar to Embodiment 1-3.

  As another modification of the first to third embodiments, all LEDs of the light emitting unit may emit the same colored light. Specifically, all are red LEDs, all are green LEDs, or all are blue LEDs. These configurations are used when radiating red light, green light, or blue light to the outside instead of emitting white light to the outside. From the above, it is possible to radiate red light, green light or blue light having a certain intensity to the outside.

(Embodiment 4)
A fourth embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the light emitting device of Embodiment 4 includes a light emitting unit 1, a base member 2, a current supply unit 3, a protective cover 4, a plurality of light detection units 50 to 55, and a control unit 6. However, the light emitting device of the first embodiment has the following characteristic portions.

  The light emitting unit 1 of the fourth embodiment includes a total of three blue LEDs by adding two blue LEDs instead of the red LED 10 and the green LED 11 of the first embodiment. The light emitting unit of the fourth embodiment is the same as the light emitting unit of the first embodiment except for the points described above.

  The protective cover 4 of Embodiment 4 is formed of a mixture in which a transparent yellow material is mixed with a particulate yellow phosphor. The yellow phosphor of the fourth embodiment is, for example, a YAG (yttrium aluminum garnet) system, and emits broad yellow light when excited by blue light emitted from three blue LEDs. The protective cover 4 transmits blue light emitted from the three blue LEDs and yellow light emitted from the yellow phosphor, so that white light is irradiated to the outside. In addition, the protective cover 4 of Embodiment 4 is the same as the protective cover of Embodiment 1 in points other than the above.

  Each of the plurality of light detection units 50 to 55 according to the fourth embodiment detects the intensity of blue light emitted from different blue LEDs. Each of the light detection units 50 to 55 transmits the detected blue light intensity to the control unit 6. The plurality of light detection units 50 to 55 of the fourth embodiment are the same as the plurality of light detection units of the first embodiment in points other than the above.

  In the control unit 6 of the fourth embodiment, a storage unit (not shown) stores in advance a reference value for the intensity of blue light. The comparison unit (not shown) inputs the intensity of the blue light detected by each of the light detection units 50 to 55 as a detection value when current is supplied to the three blue LEDs. The comparison unit compares the detection value with the reference value and outputs a comparison signal to the adjustment unit. When the detected value is different from the reference value, the adjusting unit (not shown) adjusts the current supplied to the corresponding blue LED so that the detected value is equal to or substantially equal to the reference value. In addition, the control part 6 of Embodiment 4 is the same as the control part of Embodiment 1 in points other than the above.

  As described above, according to the fourth embodiment, even when the light emitting units 1 are all blue LEDs, it is possible to radiate white light having a constant intensity to the outside.

(Embodiment 5)
Embodiment 5 of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the light emitting device of Embodiment 5 includes a light emitting unit 1, a base member 2, a current supply unit 3, a spacer 4, a protective cover 4, a plurality of light detection units 50 to 55, and However, the light emitting device of the first embodiment has the following characteristic portions.

  The light emitting unit 1 of the fifth embodiment is provided with a total of two blue LEDs and a red LED by adding a blue LED instead of the green LED 11 of the first embodiment. In addition, the light emission part 1 of Embodiment 5 is the same as that of the light emission part of Embodiment 1 in points other than the above.

  In the protective cover 4 of the fifth embodiment, a green phosphor is formed on the upper surface or the lower surface of the portion facing one blue LED. The green phosphor of Embodiment 5 is excited by light emitted from one blue LED and emits broad green light. As a method for forming the green phosphor, for example, there is a method in which the green phosphor is dispersed and held in a translucent resin such as an epoxy resin and applied to the upper surface or the lower surface. As another example, a light-transmitting resin containing a green phosphor is formed in advance in a sheet shape, and the sheet-shaped resin is bonded to the upper surface or the lower surface, or the green phosphor is formed by vapor deposition or sputtering. There are ways to do it. The protective cover 4 passes through the red light emitted from the red LED, the blue light emitted from the blue LED, and the green light emitted from the green phosphor, so that white light is irradiated to the outside. Is done. In addition, the protective cover 4 of Embodiment 5 is the same as the protective cover of Embodiment 1 in points other than the above.

  The light detection units 52 and 53 of the fifth embodiment detect the intensity of the blue light emitted from the blue LED. Each of the light detection units 50 to 55 transmits the detected red light and blue light intensities to the control unit 6. The plurality of light detection units 50 to 55 of the fifth embodiment are the same as the plurality of light detection units of the first embodiment in points other than the above.

  In the control unit 6 of the fifth embodiment, a storage unit (not shown) stores in advance reference values for the intensity of red light and blue light. When a current is supplied to each LED, the comparison unit (not shown) inputs the intensity of the colored light detected by each of the light detection units 50 to 55 as a detection value. The comparison unit compares the detection value with the reference value and outputs a comparison signal to the adjustment unit. When the detected value is different from the reference value, the adjusting unit (not shown) adjusts the current supplied to the corresponding LED so that the detected value is equal to or substantially equal to the reference value. The control unit 6 of the fifth embodiment is the same as the control unit of the first embodiment except for the points described above.

  As mentioned above, according to Embodiment 5, even if the light emission part 1 is a combination of red LED and two blue LED, white light of fixed intensity | strength can be radiated | emitted outside.

  As a modification of the fourth or fifth embodiment, instead of the yellow phosphor or the green phosphor, for example, a red phosphor may be used according to the color of light to be generated.

It is sectional drawing of the light-emitting device of Embodiments 1-5 by this invention. It is sectional drawing of the conventional light-emitting device.

Explanation of symbols

1 Light emitting unit 10 Red LED
11 Green LED
12 Blue LED
2 Base member 22 LED mounting part 23-26 Wall part 3 Current supply part 50-55 Light detection part 6 Control part

Claims (1)

A plurality of LEDs each emitting light when supplied with current;
A base member having an LED mounting portion on which the plurality of LEDs are mounted, and a wall portion provided around a region where each of the plurality of LEDs is mounted on the LED mounting portion;
A plurality of light detection units, each of which is provided on the wall and detects the intensity of light emitted from the different LEDs,
A controller that controls the current supplied to each of the plurality of LEDs so that the intensity of the light detected by each of the plurality of light detection units becomes a predetermined light intensity. A light emitting device characterized.

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