JPH10247748A - Light emitting element and surface light source device equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device which is high in luminous brightness and made to function like a point light source, by a method wherein illuminants are enhanced in arrangement density. SOLUTION: An inverted L-shaped lead 22 is arranged between leads 22a and 22b. A part of the center lead 22 sandwiched in between the leads 22a and 22b is bent above the lead 22a to serve as a pad 24. A light emitting diode(LED) chip 23 is mounted on the edge of the lead 22a, and the pad 24 of the center lead 22 located above the diode chip 23 and the diode chip 23 are connected together with a bonding wire 25. An LED chip 23 is mounted on a part of the center lead 22 located between the leads 22a and 22b, and the LED chip 23 and the pad 24 of the lead 22b are also connected together with a bonding wire 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device and a surface light source device using the light emitting device.

[0002]

2. Description of the Related Art The inventors of the present invention have proposed a surface light source device capable of obtaining a high luminance surface light source having a uniform luminance distribution by converting a point light source into a surface light source (Japanese Patent Application No. Hei 8-30107).
No. 3 has been filed.

[0003] As shown in FIG.
A point light source 3 made of a small luminous body such as a light emitting diode (hereinafter, referred to as an LED) chip is arranged at the center of the end surface (light incident end surface 5) of the light guide plate 2 made of a transparent resin having a high refractive index. On the lower surface of 2, a diffusion pattern 4 having an arc shape centered on a point light source 3 is provided. Point light source 3
The light R emitted from the light guide plate 2 enters the light guide plate 2 from the light incident end face 5 of the light guide plate 2, is totally reflected inside the light guide plate 2 and is scattered by the diffusion pattern 4 on the lower surface, and the upper surface of the light guide plate 2 (light When the angle of incidence on the light exit surface 6) reaches the critical angle of total reflection, light is emitted from the light exit surface 6 to the outside. Here, the diffusion patterns 4 provided on the lower surface of the light guide plate 2 are arranged in an arc shape centered on the point light source 3 so that the light R from the point light source 3 can be efficiently guided to the light emitting surface 6 side. In addition, the diffusion pattern density is changed so that the luminance distribution on the light emitting surface 6 becomes uniform.

In such a surface light source device 1, if the light emitting area (dimension of the light guide plate) is increased, the light emitting power of the point light source 3 must be increased accordingly in order not to lower the luminance. In that case, since the light emission power emitted from one light emitter is limited, it is necessary to use a plurality of light emitters in order to increase the light emission power of the point light source 3. For example, when used in a 1.7-inch mobile phone liquid crystal display, two LEDs are required, and in a 3.5-inch portable information terminal, 10 liquid crystal displays are used. An LED is required.

However, when a plurality of light emitters 3a are arranged and used as a point light source 3, the light emitters 3a cannot be collected at one point, and if the distance between the arranged light emitters 3a is wide, these light emitters 3a become Instead of being a point light source, it becomes a linear light source as shown in FIG. 2, and the characteristics of the surface light source device 1 are degraded.

Further, in a color-compatible surface light source device,
When whitening is performed by mixing light from light-emitting elements such as LED chips of three colors of red (R), green (G), and blue (B), if the distance between the three light-emitting elements of red, green, and blue is large, However, there is a problem that white light is not uniformly emitted from the light emission surface of the light guide plate, and color unevenness (for example, reddish on the red illuminant side and bluish on the blue illuminant side) occurs.

However, for example, FIG. 3 shows a light emitting element 7 in which two light emitters (LED chips) 9 are packaged in one package, and FIG. 5 shows a light emitting element 8 in which five light emitters 9 are packaged in one package. In the conventional light emitting device, a plurality of leads 10a, 10 and 10b are arranged in a line, and a light emitting body 9 is die-bonded on each of the leads 10a and 10, so that each light emitting body 9 is formed.
Are arranged in a row, the bonding wires 11 are passed in the direction of arrangement of the light emitters 9, the light emitters 9 on the leads 10a, 10 are connected to the adjacent leads 10, 10b by the bonding wires 11, and the light emitters 9 are connected in series. Connected. Therefore, the bonding wire 1 is provided between the luminous body 9 and the luminous body 9.
Therefore, a pad portion for connecting the light emitting elements 1 is required, so that the distance between the light emitting members 9 cannot be reduced, and the above-mentioned problem of the linear light source and the problem of the color unevenness cannot be solved.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to increase the arrangement density of a plurality of luminous bodies and increase the luminous brightness. And a point light source.

[0009]

SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a light emitting device having a plurality of leads arranged thereon, a light emitting body mounted on each of the leads, and at least a part of a lead wired in a direction different from the arrangement direction of the light emitting bodies. Characterized in that the luminous body and the lead are connected.

In the light emitting device according to the first aspect, since the conductor connecting the light emitter and the lead is in a direction different from the arrangement direction of the light emitter, a pad portion for connecting the conductor is located between the light emitters. No longer. As a result, the distance between the light emitters can be shortened, the arrangement density of the light emitters can be increased, and the light emitting element can have higher luminance and can be used as a point light source.

According to a second aspect of the present invention, there is provided a light emitting device in which a plurality of leads are arranged and a light emitting body is mounted so as to straddle between the leads. Is characterized by straddling the leads in a direction different from the arrangement direction.

A light emitting device according to a second aspect of the present invention connects the light emitting device to a lead by, for example, a bump,
Since the luminous bodies are arranged between the leads in a direction different from the arrangement direction, the distance between the luminous bodies can be shortened to increase the arrangement density of the luminous bodies, so that the luminance of the luminous element can be increased and a point light source can be used. it can.

According to a third aspect of the present invention, there is provided the light emitting device, wherein a plurality of leads are arranged, and the luminous bodies are arranged in a plurality of rows on each lead and mounted.

In the light emitting device according to the third aspect of the present invention, since the light emitting elements are arranged in a plurality of rows, the arrangement density of the light emitting elements can be increased, the light emitting element can have high brightness, and can be used as a point light source.

According to a fourth aspect of the present invention, in the light emitting device according to the third aspect, the positions of the light emitters belonging to different rows are shifted from each other along the arrangement direction of the light emitters.

The so-called delta arrangement corresponds to the fourth embodiment. This corresponds to colorization, and aims to increase the luminance of a color light emitting element and to use a point light source.

A light emitting device according to a fifth aspect is characterized in that a plurality of leads are arranged, a light emitting body is mounted on each lead, and at least a part of the light emitting body is connected in parallel by a conductive wire. .

In the light-emitting device according to the fifth aspect, since the light-emitting bodies are connected in parallel, only one pad portion is required in a portion connected in parallel. As a result, the distance between the light emitters can be shortened, the arrangement density of the light emitters can be increased, and the light emitting element can have higher luminance and can be used as a point light source.

The light emitting device according to claim 6, wherein a plurality of leads are arranged, a luminous body is mounted on each lead, and the luminous body and the lead are connected by a conductive wire. The width of the portion where the light emitting body is mounted is narrower than that of the lead.

In the light emitting device according to the sixth aspect, the width of the portion where the copper wire of the lead is connected is narrower than the width of the portion on which the light emitting device is mounted. The distance between them can be shortened. As a result, the arrangement density of the light emitters can be increased, the luminance of the light emitting element can be increased, and a point light source can be used.

According to a seventh aspect of the present invention, there is provided a surface light source device according to the first aspect.
The light-emitting device according to any one of the first to sixth aspects is characterized in that the light-emitting element is disposed to face the light incident end face of the light guide plate.

According to the surface light source device of the present invention, the light of the light emitting element turned into a point light source can be turned into a surface light source by the light guide plate. In addition, since the luminance of the light-emitting element is increased, the area of the surface light source can be increased, and a large-area surface light source device having high luminance and uniform luminance distribution can be manufactured.

[0023]

FIG. 5 is a perspective view showing a light emitting device 21 according to one embodiment of the present invention. In this light emitting element 21, one of the two leads 22a and 22b extended downward to connect to a circuit board or the like.
LED chip 23 is mounted on the inner end of a.
The inner end of the other lead 22b is a bonding wire 2
5 is a pad portion 24 for connecting wires 5. The lead 22 is also arranged between the inner ends of these leads 22a and 22b.
The lead 22a is bent in an inverted L-shape from between the portions 22b to above the inner end of the lead 22a. L of the center lead 22 is located between the leads 22a and 22b on both sides.
The ED chip 23 is die-bonded, and the upper end bent horizontally forms a pad portion 24.

A bonding wire 25 extending in the vertical direction is connected to the LED chip 23 on the lead 22a and the pad portion 24 of the center lead 22, and the LED chip 23 on the center lead 22 and the lead 22b are connected. The bonding wire 25 passed in the lateral direction is
Are connected. Therefore, since the pad portion 24 is not located between the LED chips 23 as in the conventional example,
The chips 23 can be brought close to each other, and the arrangement density of the light emitters can be increased, so that a plurality of light emitters can be used as point light sources with high luminance. For example, compared to the light emitting element 7 of FIG.
The concentration of 3 is high.

In the light emitting element 21, the legs 22a and 22b on both sides, and the portions other than the inner ends and the center lead 22 are covered with an exterior resin 26 made of, for example, white resin. The inner ends of the central lead 22 and the leads 22 on both sides are exposed from the front opening 27 of the exterior resin 26. Therefore, two LED chips 2
3 is also exposed from the front opening 27 of the exterior resin 26,
The front opening 27 of the exterior resin 26 is closed by a transparent resin 28, and the LED chip 23 is also sealed by the transparent resin 28. Therefore, the two LED chips 23 approaching each other emit light and emit light, and the light is emitted from the front opening 27 of the exterior resin 26 through the transparent resin 28.

FIGS. 6 (a), 6 (b), 6 (c), and 6 (d) are views showing a method of manufacturing the light emitting device 21. Each of the leads 22a, 2 kept in a predetermined arrangement in the form of a lead frame.
2 and 22b, as shown in FIG.
After the insert molding is performed and the exterior resin 26 is molded, it is separated from the lead frame. Next, the LED chip 23 is mounted on the leads 22 a and 22 through the front opening 27 of the exterior resin 26, and the LED chip 23 and the leads 22 and 22 b are connected by the bonding wires 25. Thereafter, a transparent resin 28 is poured into the front opening 27 of the exterior resin 26 and the LED chip 2 is
3 is sealed.

(Second Embodiment) FIG. 7 is a front view showing a light emitting device 31 according to another embodiment of the present invention. In the light emitting element 31, a plurality of leads 22 are arranged between the leads 22a and 22b at both ends, and each lead 22 is formed vertically long (that is, long in a direction perpendicular to the arrangement direction of the leads 22). . The LED chips 23 are alternately bonded on the upper side and the lower side on each of the leads 22a, 22 except for the lead 22b at one end, and are arranged in a delta. The pad portion 24 also has a lead 22 except for the lead 22a at the other end. , 22b are alternately arranged on the upper side and the lower side. The LED chips 23 alternately arranged on the leads 22a and 22 in this manner are connected to the bonding wires 2
5 in the horizontal direction so that adjacent leads 22 and 2
It is bonded to the pad portion 24 of FIG.

Also in this embodiment, the pad portion 24 for bonding the bonding wire 25 and the LE
The D chip 23 is positioned in the vertical direction, and the LED chip 23 and the LED
Since the pad portion 24 does not intervene with the chip 23, L
The ED chip 23 and the LED chip 23 can be brought closer to each other, so that the arrangement density of the light emitters can be increased, the luminance can be increased, and a point light source can be used.

(Third Embodiment) FIG. 8 is a front view showing a light emitting device 32 according to still another embodiment of the present invention.
In this embodiment, the width of the pad portion 24 of each lead 22 in the light emitting element shown in FIG.
3 is narrower than the width of the portion where the LED chip 3 is mounted, thereby making the leads 22a, 22, and 22b closer to each other, thereby shortening the distance between the LED chips 23 and increasing the concentration of the luminous body. is there.

(Fourth Embodiment) FIG. 9 is a front view showing a light emitting device 33 according to still another embodiment of the present invention.
The light emitting element 33 includes two leads 22a, 22, 22
b, the inner end of one lead 22a is a pad portion 24, and the inner end of the other lead 22b is die-bonded with a plurality of LED chips 23 arranged in a line. Pad part 24 of lead 22a and lead 2
One bonding wire 25 is continuously passed to each LED chip 23 on 2b, and the pad portion 24 and each LE
It is connected to the D chip 23. As a result, the LED chips 23 are connected in parallel.

Even with such an arrangement of the LED chips 23, since the pad portions 24 are not located between the LED chips 23, the luminous bodies are concentrated and the arrangement density of the luminous bodies is increased.
The light emitting element can be a point light source.

(Fifth Embodiment) FIG. 10 is a front view showing a light emitting device 34 according to still another embodiment of the present invention. The light emitting element 34 includes two leads 22a and 22b.
The inside end of one lead 22b and the inside end of the other lead 22a are vertically opposed over a relatively long distance, and the inside end of one lead 22b is a pad portion 24. A plurality of LED chips 23 are die-bonded in a line to the inner end of the other lead 22a. Each LED chip 23 is connected to the pad portion 24 of the lead 22b by a bonding wire 25 extending in the vertical direction.

Also in this embodiment, the LED chip 2
In the arrangement direction of No. 3, since the pad portions 24 are not located between the LED chips 23, it is possible to concentrate the light emitters, increase the arrangement density of the light emitters, and make the light emitting element a point light source.

(Sixth Embodiment) FIG. 11 is a front view showing a light emitting device 35 according to still another embodiment of the present invention. This embodiment is different from the light emitting element 34 shown in FIG.
By reducing the width of the pad portion 24 of the lead 22, the height of the light emitting element 35 is reduced, and the light emitting element 35 is made compact. The width of the pad portion 24 is not limited to the light emitting element 34 of FIG. 10 and may be smaller than the lead width of the portion where the LED chip 23 is mounted.
By reducing the width of the light emitting element, the size of the light emitting element can be reduced.

(Seventh Embodiment) FIG. 12 is a front view showing a light emitting device 36 according to still another embodiment of the present invention. In this embodiment, the LED chip 23 and the pad 2
4 are arranged in a plurality of stages in the vertical direction, and the width of the pad portion 24 between the left and right LED chips 23 is made as narrow as possible. In this light emitting element 36, the LED chip 2
3 is formed in a plurality of stages in the vertical direction, so that the LED chip 2
3, the point density is increased while the luminance is increased. It is clear that the LED chips 23 are concentrated even when compared with the light emitting element 8 of FIG. 4 which also has five LED chips.

(Eighth Embodiment) FIG. 13 is a front view showing a light emitting device 37 according to still another embodiment of the present invention. In the light emitting element 37, the leads 22 at both ends are used.
a, 22b, a relatively short elongated lead 22 between the inner ends
Are arranged in two upper and lower stages, and the upper and lower leads 22 are arranged so as to partially overlap each other in the vertical direction. Thus, each of the leads 22 has one (for example, left side) die-bonded with the LED chip 23, and the other (for example, right side) has a pad portion 24.
The D chip 23 and the pad portion 24 are vertically opposed, and a bonding wire 25 extending in the vertical direction is connected between the LED chip 23 and the pad portion 24 which are vertically opposed.

Also in this embodiment, the pad portion 24 for bonding the bonding wire 25 and the LE
The D chip 23 is positioned in the vertical direction, and the LED chip 23 and the LED
Since the pad portion 24 does not intervene with the chip 23, L
The ED chip 23 and the LED chip 23 can be brought closer to each other, so that the arrangement density of the light emitters can be increased, the luminance can be increased, and a point light source can be used.

(Eighth Embodiment) FIG. 14 is a front view showing a light emitting device 38 according to still another embodiment of the present invention. This embodiment is different from the light emitting device shown in FIG.
Are more concentrated.

In the light emitting devices shown in FIGS. 7, 8, 13 and 14, since the LED chips 23 are arranged in a delta arrangement, the red, green and blue LED chips 23 are mounted. It is preferable for the color light emitting element described above. The emission power of the red, green, and blue LED chips 23 is about 8: 1: 4.
Therefore, when the LED chips 23 of three colors are arranged in a delta arrangement, for example, as shown in FIG. 15, the number of the LED chips 23 is increased in the order of green (G), blue (B), and red (R). It is preferable to arrange them symmetrically.

(Ninth Embodiment) FIG. 16 is a front view showing a light emitting device 39 according to still another embodiment of the present invention. In the light emitting element 39, instead of using the bare chip type LED chip 23 as a light emitting body, as shown in FIG.
Is used. The intermediate leads 22 are elongated in the vertical direction and are arranged in parallel with each other. The LED chips 40 are mounted so as to straddle the leads 22a, 22, 22b alternately in the upper stage and the lower stage. Bump connection is made to 22b.

As described above, even in the case of the bump connection, the LED chips 40 can be connected in a delta manner to reduce the distance between the LED chips 40, increase the luminance, and provide a point light source.

(Tenth Embodiment) FIG. 18 is a front view showing a light emitting device 42 according to still another embodiment of the present invention. In this light emitting element 42, the vertically long leads 22
LED chips 40 having bumps 41 between a, 22, and 22b are arranged in upper and lower two stages, and the LED chips 40 are connected in series / parallel, so that the plurality of LED chips 40 are made into point light sources.

(Surface Light Source Apparatus) FIG. 19 is an exploded perspective view showing a surface light source apparatus 43 using the light emitting element 44 turned into a point light source as described above. The light guide plate 2 is made of a high refractive index material such as polycarbonate resin or methacrylic resin, and has an arc-shaped diffusion pattern (see FIG. 1) formed on the lower surface thereof.
A reflection sheet 45 is arranged on the lower surface of the light guide plate 2.
The light-emitting element 44 of the present invention is opposed to the light incident end face 5 of the light guide plate 2. Thus, the light emitted from the light emitting element 44 is guided from the light incident end face 5 into the light guide plate 2, is totally reflected inside the light guide plate 2 or is scattered in a diffusion pattern, and goes to the light emission surface 6 (upper surface). When the incident angle exceeds the critical angle of total reflection, the light exits from the light exit surface 6.

Since the light emitting element 44 of the present invention used in the surface light source device 43 is ideally configured as a point light source, the characteristics of the surface light source device for converting such a point light source into a surface light source are described below. Thus, it is possible to manufacture a surface light source device having high luminance and high uniformity.

(Liquid Crystal Display) FIG. 20 is an exploded perspective view showing a liquid crystal display 81 using the surface light source device 80 according to the present invention. A diffuse reflection sheet 82 is disposed on the front surface of the surface light source device 80, and a liquid crystal display panel 83 is disposed on the front surface. The liquid crystal display panel 83 includes a transparent electrode and a TF.
Two liquid crystal substrates (glass substrate, film substrate) 84 on which T, color filters, black matrix, etc. are formed,
A liquid crystal material is sealed between the liquid crystal substrates 85, and polarizing plates 86 are provided on both outer surfaces of the liquid crystal substrates 84 and 85.

According to such a liquid crystal display device 81, the surface light source device 80 having high light coupling efficiency between the light source 32 and the light guide plate 22 and high luminance can be used. Can be enhanced.

(Electronic Device Equipped with Liquid Crystal Display Device) The liquid crystal display device according to the present invention is a wireless information transmission device such as a mobile phone or a low power radio, a portable personal computer, an information processing device such as an electronic organizer or a calculator. It is preferable to use it for devices and the like. FIG. 21 is a perspective view showing a mobile phone 89 provided with a liquid crystal display device 81 as shown in FIG. 20 for display according to the present invention, and FIG. 22 is a functional block diagram thereof. A button switch 90 such as a numeric keypad for dial input is provided on the front of the mobile phone 89, a liquid crystal display device 81 is provided above the switch 90, and an antenna 91 is provided on the upper surface. When a dial or the like is input from the button switch 90, the input dial information or the like is transmitted from the antenna 91 to the base station of the telephone company through the transmission circuit 92. On the other hand, the input dial information and the like are sent to the liquid crystal drive circuit 93, and the liquid crystal display device 81 is driven by the liquid crystal drive circuit 93, and the dial information and the like are displayed on the liquid crystal display device 81.

FIG. 23 is a cross-sectional view according to the present invention.
And a portable information terminal 9 such as an electronic organizer or a portable personal computer having a liquid crystal display device 81 as shown in FIG.
4 is a perspective view, and FIG. 24 is a functional block diagram thereof.
When the cover 95 is opened, the portable information terminal 94 includes a key input section 96 and a liquid crystal display device 81. Inside the portable information terminal 94, a liquid crystal driving circuit 93, an arithmetic processing circuit 97, and the like are provided.
Thus, for example, when a ten key, a kana key, or the like is input from the key input unit 96, the input information is sent to the liquid crystal drive circuit 93 and displayed on the liquid crystal display device 81. Next, when a control key such as a calculation key is pressed, predetermined processing and calculation are executed in the calculation processing circuit 97, and the result is sent to the liquid crystal drive circuit 93 and displayed on the liquid crystal display device 81.

[Brief description of the drawings]

FIG. 1 is a plan view showing a surface light source device according to a prior application.

FIG. 2 is a diagram illustrating a problem of the surface light source device of the above.

FIG. 3 is a front view showing the structure of a conventional light emitting device.

FIG. 4 is a front view showing the structure of another conventional light emitting device.

FIG. 5 is a perspective view illustrating a light emitting device according to an embodiment.

FIGS. 6 (a), (b), (c), and (d) are diagrams for explaining a manufacturing procedure of the light-emitting element.

FIG. 7 is a front view illustrating a light emitting device according to another embodiment of the present invention.

FIG. 8 is a front view illustrating a light emitting device according to another embodiment of the present invention.

FIG. 9 is a front view illustrating a light emitting device according to still another embodiment of the present invention.

FIG. 10 is a front view showing a light emitting device according to still another embodiment of the present invention.

FIG. 11 is a front view showing a light emitting device according to still another embodiment of the present invention.

FIG. 12 is a front view showing a light emitting device according to still another embodiment of the present invention.

FIG. 13 is a front view illustrating a light emitting device according to another embodiment of the present invention.

FIG. 14 is a front view illustrating a light emitting device according to another embodiment of the present invention.

FIG. 15 is a diagram showing an example of an arrangement of red (R), green (G), and blue (B) LED chips arranged in a delta arrangement.

FIG. 16 is a front view showing a light emitting device according to still another embodiment of the present invention.

FIG. 17 is a front view of a bump-type LED chip.

FIG. 18 is a front view showing a light emitting device according to still another embodiment of the present invention.

FIG. 19 is a perspective view showing a surface light source device according to still another embodiment of the present invention.

FIG. 20 is an exploded perspective view of a liquid crystal display device using the surface light source device of the present invention.

FIG. 21 is a perspective view showing a mobile phone provided with a liquid crystal display device according to the present invention for a display.

FIG. 22 is a block diagram showing a configuration for driving a liquid crystal display device in the above mobile phone.

FIG. 23 is a perspective view showing a portable information terminal such as an electronic organizer provided with a liquid crystal display device according to the present invention for a display.

FIG. 24 is a block diagram showing a configuration for driving a liquid crystal display device in the portable information terminal of the above.

[Explanation of symbols]

 22a, 22, 22b Lead 23 LED chip 24 Pad 25 Bonding wire 26 Exterior resin

Claims (7)

[Claims] A plurality of leads are arranged, a luminous body is mounted on each lead, and at least a part of the luminous bodies and the leads are connected by a conductor wired in a direction different from an arrangement direction of the luminous bodies. A light-emitting element. 2. A light-emitting element having a plurality of leads arranged thereon and mounted with a light-emitting body so as to straddle between the leads, wherein at least a part of the light-emitting bodies is arranged in a direction different from the arrangement direction of the light-emitting bodies. A light-emitting element characterized by straddling between them. 3. A light emitting device comprising a plurality of leads arranged thereon, and a plurality of light emitting elements arranged in a plurality of rows on each lead and mounted. 4. The light emitting device according to claim 3, wherein the positions of the light emitters belonging to different rows are shifted from each other along the arrangement direction of the light emitters. 5. A light emitting device comprising: a plurality of leads; a light emitting body mounted on each lead; and at least a part of the light emitting body connected in parallel by a conductive wire. 6. A light-emitting element in which a plurality of leads are arranged, a light-emitting body is mounted on each lead, and the light-emitting body and the lead are connected by a conductive wire. A light-emitting element having a width smaller than a width of a part on which a body is mounted. 7. A surface light source device, wherein the light emitting element according to claim 1 is arranged to face a light incident end face of a light guide plate.