JP2006108517A - Substrate for led connection, illuminator using thereof, and display device using thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the assembly of two or more LEDs emitting light of different colors becomes a product which is not economical since the life of the assembly is decided by an LED deteriorated first, and that costs for the maintenance of the assembly is increased since it has to be replaced frequently. <P>SOLUTION: This light source apparatus has the two or more LEDs emitting light of different colors, and elements concerning the deterioration of the LEDs are set to be different by each LED so as to approximate the deterioration speed of the respective LEDs. Regarding heat generation which is the largest of the elements in connection with the deterioration, a radiation mechanism is provided at each LED to set the radiation characteristic of the radiation mechanism according to a current quantity flowing through each LED, or a light-emitting spectrum or a calorific value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technology for extending the life of a light source using LEDs (light emitting diodes) of a plurality of colors.

In recent years, devices that use LEDs as light sources are increasing, taking advantage of the fact that they can be miniaturized and have a long lifetime.
However, LEDs also have a deterioration, and the deterioration problem has become an important solution for applications that use a mixed color of LEDs having different wavelengths.
Applications that use mixed colors include white backlights that emit white by mixing three primary colors of red (hereinafter abbreviated as R) LEDs, green (hereinafter abbreviated as G) LEDs, and blue (hereinafter abbreviated as B) LEDs. The RSC, G, and B LEDs are sequentially turned on and off repeatedly, and the display of each color is integrated by the human eye for color recognition and a display device using the same. A method of displaying information contents in primary colors and mixed colors has begun to be used.

However, since the progress of deterioration of each color LED is different, there is a problem that even if the colors are initially matched, the color changes with deterioration. This problem is greatly influenced by the fact that the human eye is relatively insensitive to luminance but relatively sensitive to color.
Since this problem cannot be solved, a method for producing white by covering an expensive BLED with a YAG resin has become common in white backlight applications.

There are several proposals for extending the lifetime of LEDs.
For example, by devising the electrode of the substrate on which the LED chip is mounted, the displacement of the electrode position of the LED chip and the electrode position of the substrate is prevented and the inclination of the LED chip is prevented. There is a proposal of a method of improving by devising (for example, refer to Patent Document 1).
However, there is no disclosure about the device of the connection pad of the substrate on which the LED is mounted, and there is no description about a method for controlling the deterioration characteristics of a plurality of LED elements having different wavelengths.

There is also a proposal of using a metal conductor substrate and mounting an LED chip on the metal of the conductor substrate to improve heat dissipation characteristics (see, for example, Patent Document 2).
However, this method has a problem that the cost of the substrate is significantly increased, and it is difficult to reduce the size for use in a small device. Furthermore, there is no description about a method for controlling deterioration characteristics of a plurality of LED elements having different wavelengths.

Furthermore, there is also a proposal to improve heat dissipation characteristics by attaching a heat dissipation member to the surface of the substrate opposite to the surface on which the LED elements are mounted (see, for example, Patent Document 3).
However, even this method has a problem in miniaturization and thinning for use in a small device, and there is no description about a method for controlling the deterioration characteristics of a plurality of LED elements having different wavelengths.

  As described above, the conventional proposal focuses only on extending the lifetime of the single LED, and no effective proposal has been found regarding the lifetime of the aggregate of LEDs of a plurality of colors.

JP-A-11-177136 JP2003-101076 JP2004-6193

The problem to be solved is that the progress of deterioration of the LEDs of R, G, and B colors is different, so in the assembly in which the three LEDs are integrated into an IC, the life of the LED assembly is determined by the deterioration first. As a result, other LEDs that have not yet deteriorated and other colored LEDs that have been packaged for one LED must be discarded at the same time. For this reason, the LED assembly is a part or product with poor economic efficiency, and the maintenance cost is high because it is necessary to replace frequently.
Therefore, an object of the present invention is to make the deterioration rate of each color LED uniform and to extend the life of the LED assembly.

A feature of the present invention that solves the above-described problem is that, in a light source device having at least two LEDs that emit light of different colors, the size of the connection electrode of the LED connection substrate that connects the LEDs varies depending on the LEDs. This is a light source device.
Furthermore, the LED connection board is a flexible printed circuit board.
Furthermore, it is an illuminating device characterized by having the said LED connection board | substrate with which the said LED was mounted, and the light guide member arrange | positioned ahead of the light-projection surface of the said LED.
Further, the display device is characterized in that a display panel is disposed in front of the light emission surface of the light guide member of the light guide member disposed in front of the light emission surface of the LED of the illumination device.

Another feature of the present invention that solves the above problem is an LED connection substrate having a plurality of connection portions to which an LED assembly having a plurality of LED elements is connected, and the emission spectrum or the heat generation amount of each LED element. Alternatively, the LED connection substrate is characterized in that at least one of the size or electrode thickness of the connection electrode of the LED connection substrate to which the LED is connected is changed according to the amount of current.
Further, the LED connection board is a flexible printed circuit board.
And a light guide member disposed in front of the light emitting surface of the LED and a display panel disposed in front of the light emitting surface of the light guide member. is there.

A circuit board for LED connection having a plurality of connection electrodes connected to an LED assembly composed of LED elements of three colors of red, green, and blue, and an amount of current flowing through each of the connection electrodes connected to the LED elements Or at least one of the size or thickness of each connection electrode is changed according to the emission spectrum of the LED to which each connection electrode is connected or the amount of heat generated by each connection electrode. The circuit board for LED connection.
Furthermore, it is the circuit board for LED connection characterized by making the magnitude | size of the connection electrode of said blue LED larger than the connection electrode of LED of another color.

According to the present invention, since the degree of deterioration of each color of an LED light source composed of a plurality of colors can be approximated, the color of the LED light source device can be maintained and the life can be extended.

The light source device of the present invention has at least two LEDs that emit light of different colors, and the deterioration of each of the LEDs is determined by setting different factors relating to the deterioration of the LEDs for each of the LEDs. The speed was approximated.
Further, regarding the largest heat generation as an element relating to deterioration, a heat dissipation mechanism is provided for each LED, and the heat dissipation characteristics of the respective heat dissipation mechanisms are set according to the amount of current flowing through each LED, the emission spectrum, or the amount of heat generation.

3 shows a light source device (corresponding to the LED assembly 64 and the connecting portion 10 in FIG. 3), a lighting device (corresponding to the LED assembly 64 and the light guide member 36 in FIG. 3), and a display device (FIG. 3). 3 is a perspective view showing an example of the illumination device and the liquid crystal display panel 42).
3, 42 is a liquid crystal display panel comprising an upper transparent substrate 38 and a lower transparent substrate 40, 44 is a driver IC mounted on the transparent substrate 40, 46 is a substrate, and in FIG. 3, a flexible suitable for portable electronic devices. A printed board (hereinafter abbreviated as FPC) is used. Here, the FPC 46 has an LED connection portion 10 and an LED wiring portion 11 that follows, receives a liquid crystal drive signal from the main body of the device, supplies it to the driver IC 44, receives the LED drive signal, and receives the LED assembly. 64. 64 is an LED assembly mounted on the connection portion 10 of the FPC 46, 36 is a light guide member disposed in front of the light output surface of the LED assembly 64, and the light output surface of the light guide member 36 is the upper side of FIG. It has become.
Here, the LED assembly 64 and the connecting portion 10 of the FPC 46 form a light source device, the light source device and the light guide plate 36 form an illumination device, and the illumination device and the liquid crystal display panel 42 form a display device.
In the following drawings, the same members are denoted by the same numbers.

FIG. 4 is an example of a circuit diagram of the LED assembly 64.
In FIG. 4, 50 is a red LED (R LED), 52 is a green LED (G LED), 54 is a blue LED (B LED), and thus an LED that is an assembly of LEDs. The assembly 64 includes at least two LEDs that emit light of different colors. A plurality of LEDs may be formed on one chip, a plurality of chips, or a plurality of packages each in a separate package.
FIG. 4A shows an example in which the anodes of the LEDs 50, 52, and 54 are commonly connected to form a common terminal (C) 62, and the cathodes of the LEDs 50, 52, and 54 are independent terminals 58, 60, and 56, respectively. is there.
FIG. 4B shows an example in which the cathodes of the LEDs 50, 52, and 54 are commonly connected to form a common terminal (C), and the anodes of the LEDs 50, 52, and 54 are independent terminals.
FIG. 4C shows an example in which the anodes and cathodes of the LEDs 50, 52, and 54 are both independent terminals. This corresponds to this example in the case of a plurality of packages in which each LED is a separate package.
Thus, the LED assembly 64 can take various output terminal configurations.

FIG. 5 is a timing chart showing an example in which the color is adjusted by changing the duty ratio for passing a current to the LED.
FIG. 5A shows an example of color matching in the FSC system. In the red subfield tR in one field period tf, the R LED emits light as shown in the figure, and the green subfield tG emits G LED. In the blue subfield tB, the B LED emits light. The result of integrating these lights is that the white color is the correct condition. For adjustment, the R LED emission time at tR, the G LED emission time at tG, and the B emission time at tB The light emission time of each LED is adjusted as shown in the figure.
FIG. 5B is an example of color matching in a display method in which information content is displayed by changing the light emission color of the light source. In the period t1 where red is emitted, the R LED is used, and in the period t2 where green is emitted, the G LED is selected. In the period t3 where blue is emitted, the LEDs of B and B are emitted, in the period t4 where cyan is emitted, the LEDs of G and B are emitted, in the period t5 where yellow is emitted, the LEDs of R and G are selected. Each emits light. In the periods t4, t5, and t6 in which colors are mixed and mixed, the light emission times of the LEDs are adjusted as shown in the figure.

FIG. 6 is a timing chart showing an example in which white is adjusted by changing a duty ratio or a current value for supplying a current to the LED.
FIG. 6A shows an example in which the color is adjusted by changing the duty ratio for supplying a current to the LED in order to obtain white illumination light. The timing for turning off the R, G, B LEDs in the unit of one field period tf is ta1. To ta2 to adjust to white as shown in the figure.
FIG. 6B shows an example in which the color value is adjusted by changing the current value flowing through the LED in order to obtain white illumination light. The current value flowing through the R, G, B LED is shown in the range from I1 to I3 as shown in the figure. It is made white by adjusting each.

As shown in FIGS. 5 and 6, it is necessary to first adjust the color of the LED assembly to adjust the color variation due to the manufacturing variation of the LED. However, the degree of progress of deterioration differs depending on the LED of each color, and the degree of progress of deterioration varies depending on the adjustment. Since LED degradation appears as a decrease in the amount of emitted light, a difference in the degree of progress of degradation appears as a change in color.
In particular, in the G and B LEDs, the amount of heat generation tends to change in proportion to the current value and duty.

FIG. 7 is a diagram for explaining a duty ratio and a current value for supplying a current to the LED.
In FIG. 7A, in one field period tf, the G LED emits light during the period tg, and the B LED emits light during the period tb. Therefore, the duty ratio for flowing the current of the G LED is tg / tf, the duty ratio for flowing the current of the B LED is tb / tf, and the heat generation amount substantially corresponds to this ratio.
In FIG. 7B, a current I3 is passed through the G LED, and a current I1 is passed through the B LED, and the amount of heat generated substantially corresponds to this current value.

The LED is considered to be a useful backlight because it has a much longer lifetime than a cold cathode tube that has been used as a backlight of a conventional liquid crystal display device. However, there is a problem in applications where color is important.
This is because, for example, when a desired color is obtained with a combination of LEDs of different colors, such as a combination of LEDs of three primary colors, the initial color matching is a current value that flows through the LEDs as described in FIGS. This is possible by adjusting the duty ratio for passing a current to the LED, but the LEDs of each color have different degrees of deterioration, so even if the colors are initially matched, the color changes with deterioration. For this reason, a combination of LEDs of a plurality of colors cannot achieve the expected longevity. For example, in a white backlight, a method of emitting white by covering an expensive B LED with YAG resin has become common.
LED degradation may be due to discoloration of the resin that seals the LED chip, deterioration of the electrical coupling part, deterioration of the joint that controls light emission, etc., and it is confirmed that the degree of deterioration is closely related to temperature. Has been. That is, it has been confirmed that the progress of deterioration is fast at high temperatures and slow at low temperatures. For this reason, the conventional technology for extending the life has been biased toward suppressing the temperature rise of the LED chip, that is, improving the heat dissipation mechanism.

On the other hand, when trying to obtain a desired color with a combination of LEDs of different colors, for example, when a combination of LEDs of three primary colors is used, the degradation of the B LED is the fastest, followed by the G LED, and the R LED is I know it is the slowest. In the case of an application in which a desired color is obtained with a combination of LEDs of different colors, the lifetime is greatly shortened because the lifetime is when the color is perceived to be out of order.
One of the causes of deterioration seems to be related to the emission spectrum of each color. Since the emission spectrum becomes shorter in the order of R, G, B, the energy is increased, mainly speeding up the progress of deterioration of the resin. It is thought that.
Another cause of degradation is temperature, which accelerates each phenomenon of degradation.
In the present invention, the factors related to LED degradation are set differently for each LED, so that the degradation rate of each LED is approximated, and the change in color is delayed to extend the life of the LED assembly. In the embodiment, an example in which the deterioration rate of the LED is approximated by changing the characteristics of the heat dissipation mechanism of each color LED is shown.

FIG. 1 is a view showing an LED mounting surface side of an FPC according to a first embodiment of the present invention, and shows a portion corresponding to the LED connection substrate of the present invention. If the LED connection substrate including the connection electrode portion 11 is used as the LED connection substrate and the heat dissipation characteristics are controlled by using the wiring connected to the LED, the control range of the heat dissipation is further expanded and the effect of improving the heat dissipation characteristics is obtained. be able to.
In this embodiment, the FPC that is a flexible circuit board is used as the LED connection board in this embodiment, but a rigid board that is not a flexible board may be used as the LED connection board.
FIG. 1A is a diagram showing a wiring portion 11 in which a connecting portion 10 and a connection wiring electrode 14 for an FPC LED, which is a substrate indicated by reference numeral 46 in FIG. The connection electrode portion 12 of the connection portion 10 is provided with a B LED connection electrode 16, an R LED connection electrode 18, a G LED connection electrode 20, and an LED common electrode C connection electrode 22 as shown in the figure. The wiring portion 11 is provided with wiring electrodes 14 connected to the LED connection electrodes 16, 18, 20, and 22, respectively.
Since the heat of the LED is transmitted to the connection electrode and is in contact with air, the connection electrode serves as a heat dissipation mechanism for the LED. Therefore, in this embodiment, the area of the LED connection electrode 16 for B is set to be larger than the connection electrodes 18 and 20 for the LEDs of other colors as shown in the figure, and the heat dissipation amount of heat transmitted from the LED elements is increased. did. By setting in this way, the heat dissipation characteristics of the B LED are set larger than those of the other LEDs, and the chip temperature of the B LED that generates a large amount of heat is brought closer to the chip temperatures of the other G and R LEDs. The reason why the heat dissipation characteristic of the B LED is set larger than that of the other LEDs is that the B LED has a short wavelength of light and therefore has a larger energy and generates more heat than other LEDs. . As a result, in the LED of B, the deterioration of the sealing resin or the like was rapid.
In addition, since the deterioration rate of the B LED is faster than that of the other colors of LEDs, even if the deterioration rate of the B LED is only slowed, there is a great effect in extending the life of the LED assembly.
1B and 1C, in addition to the connection electrode 16 of the B LED, the connection electrode 20 of the G LED is set to have a larger area than the other connection electrodes 18 and 22 as shown in FIG. In this case, the area of the connection electrode is in the order of B, G, and R. This is because the degradation rates of the LEDs are in the order of B, G, and R. Therefore, as shown in FIGS. 1B and 1C, the area of each connection electrode is set differently for B, G, and R. By doing so, the deterioration rate of the LED can be approximated more.
Here, in FIG. 1B, the connection electrode 16 is also expressed as a part of the wiring electrode 14. Thus, in the present invention, the three-color LED chip composed of R, G, and B is used. LE
An FPC, which is a circuit board having a plurality of wirings or connection electrodes connected to the D element, and is related to the amount of current flowing through each of the wirings connected to the R, G, and B LED chips. An LED-connected FPC having a wiring in which at least one of a wiring width or a wiring thickness of each wiring is changed.
In FIG. 1B, the wiring area or connection electrode, which is a representative example of the embodiment that changes the wiring area or wiring width, wiring length, wiring flat area, wiring thickness, and wiring resistance of the connection electrode, corresponds to or relates to the deterioration of the LED. It was changed. LED degradation factors corresponding to this degradation include current, heat generation, emission color wavelength, temperature, etc. Corresponding to or relating to these factors, the wiring area or the wiring width of the connection electrode, the wiring length The effects of the present invention can be obtained by changing the wiring thickness, the wiring area, and the wiring resistance.

The area of each connection electrode is the amount of current flowing through each LED according to the duty ratio described in FIG. 7A or the current value described in FIG. 7B, the emission spectrum of each LED, or the heat generation of each LED. What is necessary is just to set according to quantity. The amount of current can be known relatively easily by designing the control circuit, the emission spectrum by selecting the element to be used, and the amount of heat generated by measurement.
It is also effective to change the electrode thickness of each connection electrode, not the area of each connection electrode, and change both the electrode area and the electrode thickness to change the heat capacity of the connection electrode.
In addition, since the amount of current and the amount of heat generation are mutually related in the G LED and the B LED, the method of this embodiment is particularly effective for these two LEDs.

FIG. 2 is a view showing the back surface of an FPC (flexible circuit board) which is an embodiment of an LED connection board according to a second embodiment of the present invention.
In FIG. 2A, the electrode 24 or the heat radiating member 24 is provided on the back surface of the connecting portion 10 of the FPC 46.
When the electrode or the heat radiating member 24 is provided in this way, the heat of the LED transmitted to the connection electrodes 16, 18 and 20 on the FPC surface is transferred to the back electrode or the heat radiating member 24 through the FPC having a thickness of about 25 μm. Increases heat dissipation effect. Since the amount of heat transmitted to the electrode or the heat radiating member 24 is substantially proportional to the area of the connection electrodes 16, 18, 20 on the front surface of the FPC 46, there is no change in the state in which the heat radiation characteristics differ for each of the R, G, B LEDs. .

FIG. 2B shows an example in which a B LED back electrode 26 and a G LED back electrode 28 are provided on the back surface of the connecting portion 10 of the FPC 46. The heat of the B LED and the G LED is connected to the FPC surface connection electrode. The heat radiation effect is enhanced by dissipating heat from the electrodes 26 and 28 via 16, 18 and FPC.
It is also effective to increase the heat dissipation effect by providing a B LED through hole 30 and a G LED through hole 32 for lowering the thermal conductivity and connecting to the connection electrodes 16 and 18 on the FPC surface with metal. is there.
In FIG. 2 (b), the G LED back electrode 28 has a larger area than the B LED back electrode 26. However, as heat dissipation characteristics, the area of the surface connection electrode, the surface connection electrode Since the heat dissipation characteristics are determined by the area where the back electrode on the back and the back electrode on the back surface, the number of through holes, etc., the area of the back electrode and the heat dissipation amount do not necessarily match.

FIG. 2C shows an example in which the rear LED electrode 26 for the B LED and the rear electrode 28 for the LED in addition to the rear LED electrode 28 for the G LED are provided on the back surface of the connecting portion 10 of the FPC 46. This also improves the heat dissipation characteristics of the R LED.
In FIG. 2C, a B LED through hole 30, a R LED through hole 34, and a G LED through hole 32 for lowering the thermal conductivity are provided, and the connection electrodes 16 and 18 on the FPC surface are provided. It is also effective to enhance the heat dissipation effect by connecting with metal.

FIG. 8 is a perspective view showing an example in which the LED assembly is mounted on an FPC which is an embodiment of an LED connection substrate.
In this embodiment, the FPC that is a flexible circuit board is used as the LED connection board in this embodiment, but a rigid board that is not a flexible board may be used as the LED connection board.
In FIG. 8, reference numeral 64 denotes an LED assembly. For example, R, G, and B LEDs are housed in one package and mounted on the connection portion 10 of the FPC 46.
When the LED assembly 64 has the anode common connection shown in FIG. 4 (a), the external electrode of the LED assembly 64 is the cathode electrode of the B LED, 58 is the cathode electrode of the R LED, 60 Is a cathode electrode of the G LED, and 62 is a common anode electrode. When the LED assembly 64 has the cathode common connection shown in FIG. 4 (b), the external electrode of the LED assembly 64 includes 56 as the anode electrode of the B LED, 58 as the anode electrode of the R LED, 60 is an anode electrode of the G LED, and 62 is a common cathode electrode.
The electrodes 56, 58, 60 and 62 of the LED assembly 64 are connected to the B, R, G and C LED connection electrodes 16, 18, 20, and 22 by the solder 63 by the reflow method at the connection portion 10 of the FPC 46, respectively. Has been. Therefore, the heat of the electrodes 56, 58, 60 of the LED assembly 64 is transmitted to the LED connection electrodes 16, 18, 20 with a low thermal resistance. The emission direction of each LED emission light is the direction indicated by 66.
The LED aggregate is not limited to the example of FIG. 8, and separate packages that emit light of different colors may be mounted on the connection portion 10 of the FPC 46.

FIG. 9 is a cross-sectional view showing an example in which an LED chip is mounted on a package by a wire bonding method.
The LED chip 74 having the lower surface of the chip as one of the cathode and the anode is fixed to the electrode 70 on the substrate 68 in the package with, for example, silver paste 76, and the electrode 70 is used as one electrode. The other electrode is connected to an electrode 72 on a substrate 68 in the package by a wire 78. Reference numeral 80 denotes a resin whose inner surface is mirror-finished, and protects the LED chip 74 together with the colorless and transparent resin 82 filled therein. The emission direction of the emitted light is 66 shown in the figure.
Here, most of the heat of the LED chip 74 is transferred to the electrode 70, and the electrode 70 is drawn out to the outside as the electrodes 56, 58, and 60 shown in FIG. The electrode 72 is commonly connected to the same electrode as that of the other LED chips, and is drawn out to the outside as the common electrode 62 shown in FIG.

FIG. 10 is a cross-sectional view showing an example in which an LED chip is mounted on a package by a flip chip method.
The LED chip 84 having both the anode and cathode electrodes on one side of the chip and the light emitting surface on the other side of the chip is connected to the electrode 90 on the substrate 68 in the package by using one bump as a bump 86. 90 is one electrode, and the other electrode is connected to an electrode 92 on a substrate 68 in the package by a bump 88. Reference numeral 80 denotes a resin whose inner surface is mirror-finished, and protects the LED chip 84 together with the colorless and transparent resin 82 filled therein. The emission direction of the emitted light is 66 shown in the figure.
Here, the heat of the LED chip 84 is transmitted to the electrodes 90 and 92 in proportion to the area of the bumps 86 and 88. Therefore, if the area of the bump 86 is sufficiently larger than the area of the bump 88 or the number of the bumps 86 is sufficiently larger than the number of the bumps 88, most of the heat of the LED chip 84 is transferred to the electrode 90. The electrode 90 is drawn to the outside as the electrodes 56, 58, and 60 shown in FIG. The electrode 92 is commonly connected to similar electrodes of other LED chips, and is drawn out to the outside as the electrode 62 shown in FIG.

FIG. 11 is a perspective view showing an example in which LEDs are mounted in the LED assembly by the wire bonding method.
In FIG. 11, a B LED electrode 100, an R LED electrode 102, a G LED electrode 104, and a common electrode C electrode 106 are provided on a substrate 108 in the package, and the B LED 54 is provided on each of the electrodes. , R LED 50 and G LED 52 are fixed with silver paste 76.
The LED chips 54, 50, 52 having the lower surface of the chip as one of a cathode or an anode have the electrodes 100, 102, 104 as one electrode, and the other electrode on the upper surface of the LED chips 54, 50, 52 is a wire 78. The other electrode is connected to the electrode 106 connected by. Here, most of the heat of the LED chips 54, 50, 52 is transmitted to the electrodes 100, 102, 104, and the electrodes 100, 102, 104 are extracted to the outside as the electrodes 56, 58, 60 shown in FIG. 8. The electrode 106 is commonly connected to similar electrodes of other LED chips, and is drawn out to the outside as the electrode 62 shown in FIG.

As described above, if the electrode on the side where most heat of the LED chip is transmitted is used as an individual output terminal and the terminal on which the heat is not transmitted is used as a common electrode, the heat dissipation characteristics differ for each LED color. The effect of the present invention can be obtained.
On the other hand, looking at the package on which the LED chip is mounted, the plane area of the connection electrode of the LED terminal of B in FIG. 1 of Example 1 is not nearly three times that of the other LED terminals. Even if the connection electrode 22 on the common electrode side of the LED is made larger than the connection electrodes R and G, the effect of improving the heat dissipation characteristics to the extent that the area of the connection electrode 16 is increased cannot be obtained, but some heat dissipation characteristics are obtained. The improvement effect can be obtained. For this reason, in the first embodiment, not only the heat radiation area of the connection electrodes connected to the individual terminals of the R, G, and B LEDs that are the connection electrodes 18, 20, and 22 is adjusted, but also the connection electrode 10 is common. The effect of the present invention can be obtained more by adjusting the area of the connection electrode of the electrode C.
The connection electrode of the common electrode C is described as an LED common connection electrode or LED fixed electrodes 118, 120, 122B, R, and G in Example 2 of FIG.

FIG. 12 shows a second embodiment of the present invention in which an LED chip is mounted on an FPC.
In this embodiment, the method for carrying out the present invention in the case where the electrode on the side where most of the heat of the LED chip is transferred is a common electrode will be described.
In this embodiment, the LED chip is directly mounted on the FPC.
In FIG. 12, the connection portion 10 of the FPC 46 (see FIG. 3) is provided with electrodes 118, 120, and 122 for connecting and fixing the B LED 54, the R LED 50, and the G LED 52 to the FPC electrodes, respectively. The three electrodes are electrically connected by a relatively thin wiring 116 to form a common electrode line C. On the electrodes 118, 120, and 122, the B LED 54, the R LED 50, and the G LED 52 are fixed by being bonded with, for example, silver paste. Further, an output electrode 110 for the B LED 54, an output electrode 112 for the R LED 50, and an output electrode 114 for the G LED 52 are provided, and are connected to the LED chips 54, 50, and 52 by wires 78, respectively. The electrode configuration on the FPC in FIG. 12 is the same as that in FIGS.
FIG. 12 shows a configuration for the case where the lower electrode of the LED is an anode and the common electrode needs to be an anode common, and the lower electrode of the LED is a cathode and the common electrode needs to be a cathode common. .
Since the wire 78 is a metal and has a high thermal conductivity but is thin and long, most of the heat of the LED chips 54, 50 and 52 is transmitted to the electrodes 118, 120 and 122 via the silver paste on the back surface of the LED chip. The electrodes 118, 120, and 122 are electrically connected by a relatively thin wiring 116. Since the wiring 116 is a metal, it is electrically short-circuited, but it is close to an insulating state in terms of thermal resistance. Therefore, heat according to the heat generation amount of each LED chip 54, 50, 52 is transmitted to the electrodes 118, 120, 122, and the heat dissipation characteristics can be made different for each LED as in the first embodiment.
Thus, in FIG. 12, the connection electrode of the common electrode C is divided into LED common connection electrodes or LED fixed electrodes 118, 120, 122B, R, and G, and the areas of the respective common electrodes 118, 120, and 122 are divided into LED. Depending on the color of the LED or in accordance with the heat generation characteristics of the LED.
Looking at the package on which the LED chip is mounted, in FIG. 12 of the second embodiment, the plane area of the common electrode 118 of the LED terminal of B is expanded by 2 to 1.5 times compared to the common electrodes 120 and 122 of the other LEDs. ing.
Furthermore, even if these common electrodes 118, 120, and 122 are used as one common electrode C, the heat dissipation characteristics can be improved.
In FIG. 12, the electrode flat area of only the common electrode C is changed, but the electrode flat areas of the LED connection electrodes 112, 114, 114 may be changed in the same manner as the common electrodes 118, 120, 122.
Thus, the effect of this invention is acquired by adjusting the plane area of a connection electrode and a common electrode. In other words, the heat dissipation characteristics are improved, the progress of the deterioration of the entire LED can be suppressed, and the difference in the progress of the deterioration with respect to the color of the LED can be adjusted. As a result, the reliability of the LED package component is improved. The reliability of the lighting device and the display device using the FPC or the substrate is improved.

FIG. 13 shows a third embodiment of the present invention in which LEDs are mounted by the flip chip method in the LED assembly.
13A, an output electrode 100 for the B LED 54, an output electrode 102 for the R LED 50, an output electrode 104 for the G LED 52, and a common electrode C are provided on a substrate in the LED assembly (not shown). The output electrodes 106 are provided, and the LED chips 54, 50, 52 are flip-chip connected between the output electrodes 100, 102, 104 and the common electrode 106 as shown in the figure.
Here, the bumps 86 and 88 for flip-chip mounting have a sufficiently large output electrode 100, 102, and 104 side and a small common electrode 106 side as shown in the figure. This state is shown in FIG. 13B by a cross section of the B LED 54 part. In this way, changing the size of the bump can be easily realized by a solder printing method or a conventionally known method of placing a solder ball.

    Since the bump 86 is configured to be sufficiently larger than the bump 88 in this way, most of the heat of the LED chips 54, 50, 52 is transferred to the electrodes 100, 102, 104, respectively. Therefore, if the output electrodes 100, 102, 104 are taken out as the output electrodes 56, 58, 60 of the LED assembly 64 shown in FIG. 8 and mounted on the FPC shown in FIGS. The heat dissipation characteristics can be made different for each LED.

  When the LED configuration in the LED assembly is separated from each anode terminal and each cathode terminal as shown in FIG. 4C, the terminal through which the heat of the LED chip is transmitted is always provided outside the LED assembly. Therefore, it is easy to vary the heat dissipation characteristics for each LED by applying the method described in each embodiment.

Thus, the light source device of the present invention also has the following characteristics.
The light source device of the present invention has at least two LEDs that emit light of different colors, and the deterioration of each of the LEDs is determined by setting different factors relating to the deterioration of the LEDs for each of the LEDs. The speed is approximated. Further, the light source device of the present invention includes at least two LEDs that emit light of different colors, and a heat dissipation mechanism is provided for each of the LEDs, and each of the heat dissipations according to the amount of current flowing through each of the LEDs. The heat dissipation characteristics of the mechanism are set. The light source device of the present invention is characterized in that the current amount is a current value flowing through the LED. In the light source device of the present invention, the amount of current is a duty ratio that causes current to flow intermittently through the LED. Further, the light source device of the present invention has at least two LEDs that emit light of different colors, a heat dissipation mechanism is provided for each of the LEDs, and each of the heat dissipations according to the emission spectrum that flows through each of the LEDs. The heat dissipation characteristics of the mechanism are set. In addition, the light source device of the present invention includes at least two LEDs that emit light of different colors, and a heat dissipation mechanism is provided for each of the LEDs, and each of the heat dissipation mechanisms according to the amount of heat generated by each of the LEDs. The heat dissipation characteristics are set. Moreover, the light source device of the present invention is characterized in that one of the LEDs is a blue LED, and the heat dissipation characteristics of the heat dissipation mechanism of the blue LED are enhanced compared to the heat dissipation characteristics of the heat dissipation mechanisms of the other LEDs. In addition, the light source device of the present invention has at least two LEDs that emit light of different colors, and the size of the connection electrode of the substrate to which the LEDs are connected differs depending on the LEDs. In addition, the LED connection substrate of the present invention has a plurality of connection parts to which an LED assembly having a plurality of LED elements is connected, and the LED according to the emission spectrum, heat generation amount or current amount of each LED element. At least one of the size of the connection electrode or the electrode thickness of the substrate to which is connected is changed. In the LED connection substrate of the present invention, the substrate is a flexible printed circuit board. In addition, the lighting device of the present invention includes at least the flexible printed circuit board on which the LED is mounted, and a light guide member disposed in front of the light emitting surface of the LED. The display device of the present invention includes at least the flexible printed circuit board on which the LEDs are mounted, a light guide member disposed in front of the light emission surface of the LEDs, and a light emission surface in front of the light guide member. It has the display panel provided. In addition, the flexible printed circuit board of the present invention has a plurality of connection electrodes connected to an LED assembly composed of red, green, and blue LED elements, and each of the connection electrodes connected to the LED elements. The size or thickness of each of the connection electrodes is changed in accordance with the amount of current flowing through the LED, the emission spectrum of the LED to which the connection electrode is connected, or the amount of heat generated by the connection electrode. It is characterized by that. The flexible printed circuit board of the present invention is characterized in that the size of the connection electrode of the blue LED is larger than the connection electrodes of the LEDs of other colors.

As described above, according to the present invention, the degree of progress of deterioration of each color of the LED light source composed of a plurality of colors can be approximated, so that the color of the LED light source device can be maintained and the life can be extended.

It is the figure which showed the LED mounting surface side of FPC in 1st Example by this invention. It is the figure which showed the back surface of FPC in 1st Example by this invention. It is the perspective view which showed the example of the LED light source device, the illuminating device, and the display apparatus. It is an example of the circuit diagram of a LED assembly. It is the timing chart which showed the example which changes the duty ratio which sends an electric current to LED, and adjusts color. It is the timing chart which showed the example which changes the duty ratio or electric current value which sends an electric current to LED, and adjusts to white. It is a figure explaining the duty ratio which sends an electric current to LED, and an electric current value. It is the perspective view which showed the example which mounted the LED assembly on FPC. It is sectional drawing which showed the example which mounted the LED chip in the package by the wire bonding method. It is sectional drawing which showed the example which mounted the LED chip in the package by the flip chip method. It is the perspective view which showed the example which mounted LED by the wire bonding method in a LED assembly. In the second embodiment of the present invention, the LED chip is mounted on the FPC. FIG. 6 is a diagram showing an LED mounted in a LED assembly by a flip chip method in a third embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Connection part 11 LED wiring part 12 Connection electrode part 14 Wiring electrode 16, 18, 20, 22 LED connection electrode 24 Electrode 26, 28 as heat radiating member LED Back electrode 30, 32, 34 Through hole 36 Light guide member 42 LCD panel 46 FPC
50 Red (R) LED
52 Green (G) LED
54 Blue (B) LED
56, 58, 60, 62 Electrode 70 (of LED assembly 64) Electrode 64 LED assembly 68 Substrate 74 in package LED chip 76 Silver paste 78 Wire 84 LED chip 86, 88 Bump 90 Electrode 100, 102, 104 Output electrode 106 LED common connection electrode or LED fixed electrode for output electrodes 118, 120, 122 B, R, G for common electrode C

Claims (9)

In a lighting device having at least two LEDs that emit light of different colors,
A lighting device, wherein the size of the connection electrode of the LED connection substrate to which the LED is connected varies depending on the LED.   The lighting device according to claim 1, wherein the LED connection board is a flexible printed circuit board.     The lighting device according to claim 1, comprising at least the LED connection substrate on which the LED is mounted, and a light guide member disposed in front of a light emission surface of the LED.   An LED connection substrate having a plurality of connection portions to which an LED assembly having a plurality of LED elements is connected, wherein the LEDs are connected in accordance with the emission spectrum, the heat generation amount or the current amount of each LED element. A substrate for LED connection, wherein at least one of the size or thickness of the connection electrode of the connection substrate is changed.   The LED connection board according to claim 4, wherein the LED connection board is a flexible printed circuit board.   The display panel is disposed in front of the light emitting surface of the light guide member of the light guiding member disposed in front of the light emitting surface of the LED of the lighting device according to claim 1, 2 or 3. Characteristic display device.   A light guide member disposed in front of the light emission surface of the LED of the LED connection substrate according to claim 4 or 5 and a display panel disposed in front of the light emission surface of the light guide member. Characteristic display device.   A circuit board for LED connection having a plurality of connection electrodes connected to an LED assembly composed of LED elements of three colors of red, green, and blue, and an amount of current flowing through each of the connection electrodes connected to the LED elements Or at least one of the size or thickness of each connection electrode is changed according to the emission spectrum of the LED to which each connection electrode is connected or the amount of heat generated by each connection electrode. A circuit board for LED connection. 9. The circuit board for LED connection according to claim 8, wherein the connection electrode of the blue LED is made larger than the connection electrode of another color LED.

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