JP2010258209A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device of high efficiency and superior additive color mixing characteristics which is difficult to produce in a conventional additive color mixing type light-emitting device wherein a plurality of LED elements are arranged by lamination. <P>SOLUTION: This light-emitting device has a light-emitting section wherein a plurality of LED elements of different luminescent colors are arranged by lamination, and a drive controlling means which individually supplies a drive current to each LED element. The plurality of LED elements constituting the light-emitting section have different sizes of areas, and are so arranged by laminating that the centers of the respective LED elements almost accord with one another. The drive controlling means varies the drive current of individual LED element to control a color level of the luminescent color. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light emitting device using an LED element used as a backlight or illumination in a color display device or the like, and more particularly to a light emitting device that converts red LED, green LED, and blue LED into a light emitting color with high color mixing properties. .

  In recent years, since LED elements (hereinafter referred to as LEDs) are semiconductor elements, they have a long life and excellent driving characteristics, and are small, have high luminous efficiency, and have a bright emission color. It has come to be widely used for lighting and lighting.

  In particular, since highly efficient LEDs have been developed for the three primary colors of red (R), green (G) and blue (B) in recent years, additive color mixing type LED light emitting devices are used. This additive color mixing type LED light emitting device emits white light by simultaneously emitting LEDs of three colors of R, G, and B, and performs color display by the white light source and the color filter of the display device. The white light is used as a lighting device.

  However, in this additive color mixing type LED light emitting device, each LED of R, G, B is mounted and arranged on a substrate in a plane to emit light, so that the light emission of each color appears to be separated. In order to perform mixing, it is necessary to dispose a diffusion plate or the like on the light emitting surface to enhance the diffusion effect, and it is difficult to obtain a light emission color with high color mixing property due to dispersed light emission.

  R, G, and B LEDs are stacked as a configuration that solves the disadvantages of the additive color mixing type LED light emitting device in which R, G, and B LEDs are mounted and arranged in a plane on a substrate to emit light. A layered additive color mixing type LED light emitting device has been proposed in which light emitting points are superposed to obtain a light emitting color with high color mixing properties (for example, Patent Document 1 and Patent Document 2).

A conventional additive color mixing type LED light emitting device will be described below.
In Patent Document 1, each of R, G, and B LEDs having the same area is stacked and arranged so that the lower layer LED transmits light through the upper layer LED and further controls the injection current to each LED to control each LED. By optimizing the light intensity of the LED, characters and images of a desired color are displayed.

  In Patent Document 2, the area of each LED of R, G, B is formed large, medium, and small, the LED having the largest area is arranged on the lower side, and further, the areas are stacked upward in the order of medium and small. By arranging the LED, a part of the light emitted from the lower LED is transmitted through the upper LED, and the other LED directly emits light, thereby increasing the light emission efficiency of the lower LED.

JP 2002-43627 A (FIGS. 1 and 4) Japanese Patent No. 3378465 (FIG. 60)

  Since the proposal of the above-mentioned Patent Document 1 is configured by laminating and arranging R, G, and B LEDs having the same area, all of the light emission of the lower layer LEDs is transmitted through the upper layer LED, so Since the arrangement and the area are equal to the light emitting direction, a beautiful display in which the light emitting positions of the respective light emitting sources are aligned is possible as a color display device, and further, the R is compared with the case where the LEDs are arranged in a shifted plane. , G, and B can be reduced to one third, and a color display device with high resolution can be provided.

  However, since all of the light emission of the lower layer LEDs is transmitted through the upper layer LED, it is necessary to increase the supply current in order to increase the light emission of the lower layer side LED. There is a problem in that the supply current to the lowermost LED that emits light through the two LED layers is too large for the LED, the heat generation of the lower LED increases, and the life as a semiconductor element is shortened. is there.

In addition, the proposal of Patent Document 2 forms the areas of the R, G, and B LEDs in large, medium, and small areas, arranges the LED having the largest area on the lower side, and further increases the area in the order of medium and small. By laminating the upper part, the lower LED emits part of the light transmitted through the upper LED, and the other part directly emits light, thereby increasing the luminous efficiency of the lower LED, There is an advantage that an increase in the supply current of the lower LED can be reduced.

  However, since the LEDs formed in large, medium, and small areas are aligned on one side, the light emission positions of the R, G, and B LEDs are shifted, and this shifted portion is There is a problem that it becomes difficult to obtain a light emission color with high color mixing properties due to dispersed light emission.

An object of the present invention is to solve the above-described problems, and in an LED light-emitting device, the mounting area is reduced and the density is increased by stacking a plurality of LEDs, and an emission color with high color mixing properties is obtained. An object of the present invention is to provide an additive color mixed type LED light emitting device capable of achieving the above.

  In order to achieve the above object, in the present invention, a light emitting device having a light emitting section in which a plurality of LED elements of different emission colors are arranged and a drive adjusting means for individually supplying a driving current to each LED element of the light emitting section. The plurality of LED elements constituting the light-emitting portion have different areas and are stacked so that the centers of the LED elements substantially coincide with each other, and the drive adjusting means drives the individual LED elements. The present invention is characterized in that the color mixing level of the luminescent color is adjusted by varying the current.

  According to the above configuration, a plurality of LEDs are stacked to reduce the mounting area and increase the density, and the LED elements are stacked so that the centers of the LED elements substantially coincide with each other. By adjusting the color mixing level of the luminescent color by varying the current, it is possible to provide an additive color mixing type LED light emitting device having a luminescent color with high color mixing properties.

  In other words, by arranging a plurality of LED elements of different emission colors in a stacked manner, the effective area of each LED is made the same as much as possible, and by slightly adjusting the difference in the area of each remaining LED with the drive current, the LED drive current difference is reduced. The LED is reduced to reduce the heat generation deterioration of the LED, and the center of each LED is matched to obtain a light emission color with high color mixing.

  The plurality of LED elements may be a red LED, a green LED, and a blue LED, and the emission color may be white emission.

  According to the above configuration, it is possible to provide an additive color mixing type LED light emitting device having a white color with high color mixing properties as a backlight.

  The light emitting unit may be formed by stacking a plurality of LED elements having a rectangular shape and different areas.

  It is preferable that the light emitting unit is configured by stacking a plurality of LED elements having the same length and different widths.

  The light emitting unit may be configured by stacking a plurality of LED elements having a rectangular shape and different areas at different angles in a plane.

  As described above, according to the present invention, the mounting area can be reduced and the density can be increased by stacking a plurality of LEDs, and the LED elements can be stacked so that the centers of the LED elements substantially coincide with each other. By changing the drive current of the LED element and adjusting the color mixture level of the emission color, it is possible to provide an additive color mixing type LED light emitting device having a light emission color with high color mixing properties.

It is a block diagram of the light-emitting device in 1st Embodiment of this invention. It is a top view of the light emission part in the light-emitting device shown in FIG. It is AA sectional drawing of the light emission part shown in FIG. It is a top view of the light emission part in 2nd Embodiment of this invention. It is AA sectional drawing of the light emission part shown in FIG. It is BB sectional drawing of the light emission part shown in FIG. It is a top view of the light emission part in 3rd Embodiment of this invention. It is AA sectional drawing of the light emission part shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram of a light emitting device according to a first embodiment of the present invention, FIG. 2 is a plan view of a light emitting unit in the light emitting device shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along line AA of the light emitting unit shown in FIG. .

In FIG. 1, reference numeral 1 denotes a light emitting device, which includes a light emitting unit 2 and a drive adjusting means 10. The light-emitting unit 2 has a configuration in which a plurality of LED elements having different emission colors are stacked, and in this embodiment, the light-emitting unit 2 is composed of a large-area R • LED 4, a medium-area G • LED 5, and a small-area B • LED 6. In a state where the center lines S of the LEDs are substantially matched from the side, the large area R • LED 4, the medium area G • LED 5, and the small area B • LED 6 are stacked in this order.

  The drive adjustment means 10 includes an R / LED drive circuit 11, a G / LED drive circuit 12, and a B / LED drive circuit 13. The R / LED drive circuit 11 supplies a drive current to the R / LED 4 in an adjustable manner. The LED driving circuit 12 supplies G / LED 5 with an adjustable driving current, and the B / LED driving circuit 13 supplies B / LED 6 with an adjustable driving current.

  2 is a plan view of the light emitting unit 2 shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along line AA of the light emitting unit 2 shown in FIG. 2. Connection electrodes 3a to 3f are provided around the upper surface of the circuit board 3. In addition, a large area R • LED 4, a medium area G • LED 5, and a small area B • LED 6 at the center of the circuit board 3 substantially align the center line S of each LED from the lower surface side as shown in FIG. In this state, a large area R • LED 4, a medium area G • LED 5, and a small area B • LED 6 are stacked in this order.

  The pad electrodes 4a and 4b of the R • LED 4 are connected to the R • LED drive circuit 11 of the drive adjusting means 10 shown in FIG. 1 by wire bonding to the connection electrodes 3a and 3f. The pad electrodes 5a and 5b are connected to the G / LED drive circuit 12 of the drive adjusting means 10 by wire bonding to the connection electrodes 3c and 3d, and the pad electrodes 6a and 6b of the B / LED 6 are connected to the connection electrode 3b. 3e is connected to the B / LED drive circuit 13 of the drive adjusting means 10 by wire bonding, and the whole is sealed with the sealing resin 15.

  Next, the adjustment operation of the light emitting device 1 will be described. As shown in FIG. 1, first, only the R / LED drive circuit 11 of the drive adjustment means 10 is brought into a drive state, and only the R / LED 4 is turned on. In this state, the amount of light emitted from the light emitting surface H is measured, and the R / LED drive circuit 11 is adjusted so that the measured amount becomes a predetermined value. Next, only the G / LED drive circuit 12 is driven, and only the G / LED 5 is turned on. In this state, the amount of light emitted from the light emitting surface H is measured, and the G / LED driving circuit 12 is adjusted so that the measured amount becomes a predetermined value. Further, only the B / LED drive circuit 13 is driven, and only the B / LED 6 is lit. In this state, the amount of light emitted from the light emitting surface H is measured, and the B / LED drive circuit 13 is adjusted so that the measured amount becomes a predetermined value.

  By this adjustment, the light amount adjustment in accordance with the effective area of each LED is completed, and the light emission amount of each LED is matched. In order to adjust the color mixing of white light from this state, the R • LED 4, G • LED 5, B • LED 6 are turned on simultaneously, and the color mixing property on the light emitting surface H is measured. Then, fine adjustment of each color LED drive circuit is performed so that the color mixing property of the white light is optimized to optimize the color mixing property of the white light. The light emission lines P shown in FIG. 1 indicate the light emission state from each LED and the color mixture state, and color mixture is performed by direct light emission P1, transmitted light P2, and oblique light P3.

Next, a second embodiment of the present invention will be described with reference to FIGS.
4 is a plan view of the light emitting unit 20 according to the second embodiment of the present invention, FIG. 5 is a cross-sectional view taken along line AA of the light emitting unit 20 shown in FIG. 4, and FIG. 6 is a cross section taken along line BB of the light emitting unit 20 shown in FIG. FIG. Note that the basic configuration of the light emitting unit 20 is the same as that of the light emitting unit 2 shown in FIG. 2, and the same elements are denoted by the same reference numerals and redundant description is omitted.

  The light emitting unit 20 in the second embodiment differs from the light emitting unit 2 in the first embodiment in the shape of each LED, and the shape of each LED in the light emitting unit 2 is a rectangular shape and the area of each LED is different. On the other hand, the shape of each LED in the light emitting unit 20 is a rectangle with the same length and different width, and the area is different.

That is, the R • LED 24, the G • LED 25, and the B • LED 26 have the same length L as shown in FIG. 5, and the widths are different in the order of W1> W2> W3 as shown in FIG. In the state where R • LED 24, medium area G • LED 25, and small area B • LED 26 are formed, and the center line S of each LED is substantially matched from the lower surface side, large area R • LED 24, medium area G • LED The LED 25 and the small area B LED 26 are stacked in this order.

  According to the above configuration, the length L of each LED in the light emitting unit 20 can be made the same, and the pad electrodes can be arranged in the longitudinal direction thereof. There is an advantage that the connection is facilitated by making the lengths substantially equal.

Next, a third embodiment of the present invention will be described with reference to FIGS.
FIG. 7 is a plan view of the light emitting unit 30 according to the third embodiment of the present invention, and FIG. 8 is a cross-sectional view taken along line AA of the light emitting unit 30 shown in FIG. Note that the basic configuration of the light emitting unit 30 is the same as that of the light emitting unit 20 shown in FIG. 4, and the same elements are denoted by the same reference numerals and redundant description is omitted.

  The light emitting unit 30 in the third embodiment is different from the light emitting unit 20 in the second embodiment in the arrangement of each LED. In the light emitting unit 20, the LEDs having a rectangular shape and different areas are arranged side by side. In the part 30, each rectangular LED having a different area is stacked and arranged at different angles in a plane.

  That is, the R · LED 34, G · LED 35, and B · LED 36 shown in FIG. 7 have the same length L as the R · LED 24, G · LED 25, and B · LED 26 shown in FIG. 4, and the width is W1> W2> W3. The large-area R • LED 34, the medium-area G • LED 35, and the small-area B • LED 36, which are different in the order of The large-area R • LED 34, the medium-area G • LED 35, and the small-area B • LED 36 are stacked in this order.

  In addition, in this embodiment, it arrange | positions by shifting every 60 degree | times as a plane different angle which arrange | positions each LED, and the length L is the same as the rectangular shape of each LED, and width W1, W2, Although W3 is changed in accordance with the effective area, the length of each LED may be changed in accordance with the effective area.

  According to the above configuration, since the LEDs are arranged in an intersecting manner according to the arrangement angle, the area of the stacked portion of each LED is small, and the area of the portion that directly emits light is large. Get better. Accordingly, a light emitting device with high luminous efficiency as a whole can be provided.

  In each embodiment of the present invention, one white light emitting device has been described. However, the present invention is not limited to this, and a large-sized large screen can be obtained by arranging a plurality of light emitting devices shown in the embodiment in a plane. The light-emitting device can be used, and is not limited to white light emission, and can be used as a color light-emitting device using a combination other than R, G, B, and LED.

DESCRIPTION OF SYMBOLS 1 Light-emitting device 2, 20, 30 Light-emitting part 3 Circuit board 3a-3f Connection electrode 4, 24, 34 R * LED
5, 25, 35 G LED
6, 26, 36 B LED
4a, 4b Pad electrode 5a, 5b Pad electrode 6a, 6b Pad electrode 10 Drive adjustment means 11 R / LED drive circuit 12 G / LED drive circuit 13 B / LED drive circuit 15 Sealing resin

Claims (5)

  A light-emitting device having a light-emitting unit in which a plurality of LED elements having different light emission colors are stacked and a drive adjustment unit that individually supplies a drive current to each LED element of the light-emitting unit, and a plurality of components that constitute the light-emitting unit The LED elements have different areas and are stacked so that the centers of the LED elements substantially coincide with each other, and the drive adjusting means varies the drive current of the individual LED elements to adjust the color mixing level of the emission color. A light-emitting device that is adjusted.   The light emitting device according to claim 1, wherein the plurality of LED elements are a red LED, a green LED, and a blue LED, and a light emission color is white light emission.   The light-emitting device according to claim 1, wherein the light-emitting unit is configured by stacking a plurality of LED elements having a rectangular shape and different areas.   The light-emitting device according to claim 3, wherein the light-emitting portion is configured by stacking a plurality of LED elements having equal lengths and different widths. 5. The light emitting device according to claim 3, wherein the light emitting unit is configured by stacking and arranging a plurality of LED elements having a rectangular shape and different areas at different angles in a plane.

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