JPH1153919A - Semiconductor planar light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To emit high brightness intermediate color or a mixed color for a semiconductor planar light source. SOLUTION: A fluorescent cover 8 to which phosphor has been applied is adhered to other main surface 1b of a light guide plate 1. Wavelength of irradiated light from a semiconductor light-emitting element 4 is converted via phosphors and discharged from the light guide plate 1. Brightness reduction due to converted wavelength can be suppressed to the minimum because light diffusion because of the phosphors inside the sufficiently thin film-shaped fluorescent cover 8 being comparatively small. Light having a wavelength different from that of the light emitted from a commercially available semiconductor light-emitting element can be obtained by means of the fluorescent cover 8. Lights of different wavelengths can be extracted easily by changing the fluorescent cover 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar light source using a semiconductor light emitting device, and more particularly, to a semiconductor planar light source that converts the wavelength of light emitted from the light emitting device and emits the light to the outside of a light guide plate.

[0002]

2. Description of the Related Art A light emitting device in which a light emitting diode chip fixed on a substrate is sealed with a transparent resin is known. For example, in a light emitting diode disclosed in Japanese Patent Publication No. Sho 60-43040, a recess is formed at the center of the top surface of the insulating block, and one end of each is located at the bottom of the recess.
A light emitting diode substrate is bonded to the bottom of the recess of the support base on which the two metal layers are formed. The electrode of the light emitting diode and the end of the metal layer located at the bottom of the recess are connected by a thin metal wire, and only the recess of the light emitting diode is sealed with a transparent resin. In Japanese Utility Model Laid-Open No. 4-114080, a plurality of first and second wiring conductors having light reflectivity are provided along the longitudinal direction of an insulating substrate, and light is emitted to each of the first and second wiring conductors. A light emitting display device in which a light emitting element and a second or first wiring conductor are connected via a fine lead wire after fixing the element, and the light emitting element and the fine lead wire are covered with a light transmitting resin body filled in a concave portion is disclosed. Have been.

A known planar light source using a semiconductor element is as follows.
As shown in FIGS. 4 and 5, a plate-shaped light guide plate (1) made of an acrylic resin or a polycarbonate resin, and a light-emitting element assembly (1) arranged on a pair of opposed side surfaces (1c) of the light guide plate (1). 2). Each of the pair of light emitting element assemblies (2) includes a printed circuit board (3), a plurality of semiconductor light emitting elements (light emitting diode chips) (4) fixed to the printed circuit board (3), and an epoxy-based material having optical transparency. A plurality of resin sealing bodies (5) made of resin or the like and covering each semiconductor light emitting element (4) and fixed to the printed circuit board (3)
And One main surface (1a) of the light guide plate (1)
Is subjected to graining (matting) and a light-reflective film (6) is adhered to the entire surface. The other main surface (1b) of the light guide plate (1) is mirror-finished, and a strip-shaped light-reflective film (7) is adhered to the periphery. Although not shown, a pair of lead electrodes formed at both ends in the longitudinal direction of the back surface of the printed circuit board (3) are electrically connected to an anode electrode and a cathode electrode of the semiconductor light emitting element (4).
The plurality of resin sealing bodies (5) include a pair of inclined surfaces (5a, 5b) inclined with respect to the printed circuit board (3) and a flat portion (5a) formed between the pair of inclined surfaces (5a, 5b). 5c), and a pair of adjacent resin sealing bodies (5) are formed so as to protrude from the printed circuit board (3) at a certain interval from each other.

As shown in FIGS. 4 and 5, a light guide plate (1)
A plurality of recesses (1 g) separated from each other by a certain distance in the width direction
Are intermittently formed on the side surface (1c) of the light guide plate (1).
Each of the concave portions (1g) on the side surface (1c) of the light guide plate (1)
Slope (1d, 1e) and adjacent slope (1d, 1e)
And a flat surface (1f) formed between them. Flat side surface (1h) of light guide plate (1) between adjacent concave portions (1g)
Is formed. When the light emitting element assembly (2) is mounted on the side surface (1c) of the light guide plate (1), the resin sealing body (5) is arranged in the recess (1g), and one main surface (1) of the light guide plate (1) is provided. 1
a) and a resin sealing body (5) parallel to the other main surface (1b)
One side surface and the other side surface are substantially flush with one main surface (1a) and the other main surface (1b) of the light guide plate (1), respectively, and function as an extension of the light guide plate (1). A strip-shaped light-reflective film (7) is attached to one side and the other side of the resin sealing body (5) and the main surface (1b) between the adjacent concave portions (1g) of the light guide plate (1). The resin sealing body (5) can be fixed to the light guide plate (1).

In the planar light source shown in FIGS. 4 and 5, light emitted from each semiconductor light emitting element (4) of the pair of light emitting element assemblies (2) is applied to a flat surface via a resin sealing body (5). (1f)
After being introduced into the light guide plate (1) from the side surface (1c) including the inclined surfaces (1d, 1e) and reflected on the light reflective film (6), the other main surface (1b) of the light guide plate (1) ) Is emitted to the outside of the light guide plate (1). The emission color of this planar light source is determined by the intrinsic emission wavelength of the semiconductor light emitting element (4). For example, if a GaAlP-based, GaP-based, and GaN-based semiconductor light-emitting element (4) is used, the emission color is: They are red, green and blue, respectively. If a GaAs-based semiconductor light emitting device (4) is used, an infrared light emitting planar light source can be obtained.

[0006]

In recent years, in order to distinguish various display states with different light-emitting colors, it has been desired to realize a planar light source that emits light in an intermediate color of red, green, and blue, or a mixed color such as white. I have. In view of the above, an object of the present invention is to provide a semiconductor planar light source that can emit such intermediate colors or mixed colors and has high luminance.

[0007]

A semiconductor planar light source according to the present invention comprises a plate-like light guide plate (1) and a light emitting element assembly (1) attached to at least one side (1c) of the light guide plate (1). 2), a light-reflective film (6) fixed to one main surface (1a) of the light guide plate (1), and a fluorescent cover (6) fixed to the other main surface (1b) of the light guide plate (1). 8). The light emitting device assembly (2) includes a substrate (3) and a plurality of semiconductor light emitting devices (4) fixed to an upper surface of the substrate (3).
And a plurality of resin sealing bodies (5) formed on the upper surface of the substrate (3) so as to cover the semiconductor light emitting element (4) and abut on the side surface (1c). The fluorescent cover (8) contains a phosphor that absorbs light passing through the fluorescent cover (8) and generates light having a wavelength different from the wavelength of the absorbed light. Light emitted from the semiconductor light emitting element (4) is introduced into the light guide plate (1) from the side surface (1c), and then directed into the fluorescent cover (8), and further passes through the fluorescent material of the fluorescent cover (8). The light is then wavelength-converted and emitted from the other main surface (1b) side of the light guide plate (1).

[0008] Since the phosphor is added to the fluorescent cover (8) and is not added to the resin sealing body (5) and the light guide plate (1), the fluorescent substance is added to the inside of the resin sealing body (5) and the light guide plate (1). There is no light scattering by the phosphor. Further, since the light scattering by the phosphor is relatively small in the sufficiently thin film-like fluorescent cover (8), a decrease in luminance due to wavelength conversion can be suppressed to a minimum. With the fluorescent cover (8), light having a different wavelength from the light generated from a commercially available semiconductor light emitting element can be extracted. Also, the fluorescent cover (8) can be easily replaced to extract light of different wavelengths.

In the embodiment of the present invention, the light guide plate (1) is provided with a plurality of recesses (1g) separated from each other by a fixed distance in the width direction. The plurality of resin sealing bodies (5) are provided on the light guide plate (1).
Are fixed on the substrate (3) at a predetermined distance from each other in the width direction, and the semiconductor light emitting element (4) is embedded in the corresponding resin sealing body (5). Each of the resin sealing bodies (5) is arranged in the corresponding recess (1g) of the light guide plate (1). Each of the concave portions (1g) of the side surface (1c) of the light guide plate (1) has an inclined surface (1d, 1e) and a flat surface (1f) formed between adjacent inclined surfaces (1d, 1e). Have. Each of the resin sealing bodies (5) is formed on an inclined surface (1d, 1e) of the light guide plate (1).
And the inclined surfaces (5a, 5b) facing each other and the inclined surfaces (5a, 5b).
b) a flat surface (1f) of the light guide plate (1) formed during
And a flat surface (5c) facing the same. A fluorescent cover (8) is fixed to the other main surface (1b) of the light guide plate (1) with an adhesive of a light transmitting resin, and an air layer between the light guide plate (1) and the fluorescent cover (8) is formed. Removes relatively easily and improves luminous efficiency. Further, the resin sealing body (5) of the light emitting element assembly (2) is fixed to the side face (1c) of the light guide plate (1) with an adhesive of a light transmitting resin, and the resin sealing body (5) and the side face are bonded. (1
c) to remove the air layer relatively easily and improve the luminous efficiency.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a semiconductor planar light source according to the present invention will be described below with reference to FIGS. Figure 1
In FIG. 3, the same portions as those shown in FIGS. 4 and 5 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, in the semiconductor planar light source according to the present embodiment, a fluorescent cover (8) to which a phosphor is added is provided.
To the other main surface (1b) of the light guide plate (1). The resin sealing body (5) of the light emitting element assembly (2) is fixed to the side surface (1c) of the light guide plate (1) with an adhesive of a light transmitting resin,
The air layer between the resin sealing body (5) and the side surface (1c) can be removed relatively easily, and the luminous efficiency can be improved. The fluorescent cover (8) conforms to the planar shape of the light guide plate (1) and covers the entire other main surface (1b) of the light guide plate (1). A fluorescent cover (8) to which a phosphor is added is attached to the other main surface (1b) of the light guide plate (1), and light emitted from the semiconductor light emitting element (4) is transmitted through the fluorescent cover (8) to a wavelength. The light is changed and irradiated from the other main surface (1b) side of the light guide plate (1).

The fluorescent cover (8) includes a resin base material having elasticity and translucency, and a phosphor mixed in the resin base body and emitting fluorescence when excited by light emission of the semiconductor light emitting element (4). Including. The resin substrate is a translucent polyester resin,
Acrylic resin, urethane, nylon, silicone resin,
Vinyl chloride, polystyrene, bakelite, CR39
(Acrylic glycol carbonate resin) and the like. Urethane, nylon, and silicone resin impart a certain degree of elasticity to the fluorescent cover (8), so that it can be easily attached to the light guide plate (1).

The phosphor which emits fluorescence by being excited by the light emission of the semiconductor light emitting element (4) in the resin base material absorbs the light when irradiated with the light, and has a wavelength different from the wavelength of the light. The substrate is made of a metal such as zinc, cadmium, magnesium, silicon, yttrium and an oxide such as a rare earth element, a sulfide,
Selected from inorganic phosphors such as silicates and vanadates,
Those of copper, iron and nickel are unsuitable.

The activator is silver, copper, manganese, chromium, eurobium, cerium, zinc, aluminum, lead, phosphorus, arsenic, gold or the like, and a small amount of about 0.001% to several% is generally used. As a flux, sodium chloride, potassium chloride, magnesium carbonate, and barium chloride are used. In addition to the inorganic phosphors, organic phosphors such as fluorescein, eosin, oils (mineral oil), and commercially available fluorescent pigments and fluorescent dyes can be used.

Light emitted from the semiconductor light emitting element (4) of the light emitting element assembly (2) is introduced into the light guide plate (1) from the side surface (1c) through the resin sealing body (5), and the light is reflected. The light is reflected by the film (6) toward the other main surface (1b) of the light guide plate (1). The light emitted from the other main surface (1b) of the light guide plate (1) to the outside of the light guide plate (1) is irradiated to the fluorescent cover (8) to excite the phosphor in the fluorescent cover (8).

In this embodiment, a blue-emitting GaN-based semiconductor light-emitting device (4) having an emission peak near 430 to 480 nm is used. For example, the base material contains zinc sulfide and cadmium sulfide, and the activator is copper, and The agent comprises a phosphor consisting of barium chloride and potassium oxide. When the blue light emitted from the light emitting element (4) is emitted from the light guide plate (1) and irradiates the fluorescent cover (8), the phosphor in the fluorescent cover (8) has a wavelength around 430 to 480 nm. And emits light having an emission peak near 500 to 600 nm, so that the wavelength-converted light can be emitted to the outside of the fluorescent cover (8). Light that has passed through the fluorescent cover (8) without being wavelength-converted by the fluorescent material and transmitted through the fluorescent cover (8) is also emitted from the fluorescent cover (8), so that a mixed color of blue light emission and light of 500 to 600 nm wavelength-converted by the fluorescent material. Are observed from the fluorescent cover (8). That is, by using the fluorescent cover (8), light having a wavelength different from the light generated from a commercially available semiconductor light emitting device can be extracted. Light of different wavelengths can be extracted by changing the type of phosphor contained in the fluorescent cover (8) or by changing the content of the phosphor in the fluorescent cover (8). In the surface light source of the present embodiment,
Since the wavelength is converted by the sufficiently thin film-like fluorescent cover (8), light scattering in the fluorescent cover (8) is relatively small, and a decrease in luminance is suppressed to a minimum. In the planar light source of the present embodiment, the other main surface (1) of the light guide plate (1) is used.
Since b) is mirror-finished, there is an advantage that air hardly remains between the fluorescent cover (8) and the light guide plate (1).

It is conceivable that the light guide plate (1) itself contains a phosphor to obtain the same effect. However, if the light guide plate (1) contains a phosphor, the phosphor causes the light guide plate (1) to contain the same in the light guide plate (1). Light scattering is increased, and a defect that the light emission luminance is reduced occurs. However, in the present invention, the fluorescent substance is contained in the fluorescent cover (8), the resin sealing body (5) and the light guide plate (1).
Since it is not added in the inside, light scattering by the phosphor does not occur in the resin sealing body (5) and the light guide plate (1). Further, since the light scattering by the phosphor is relatively small in the sufficiently thin film-like fluorescent cover (8), a decrease in luminance due to wavelength conversion can be suppressed to a minimum. When the fluorescent cover (8) is attached to one main surface (1a) of the light guide plate (1), the light whose wavelength has been uniformly converted is converted to the light guide plate (1).
Cannot be taken out from the other main surface (1b).

A fluorescent cover (8) is applied to the other main surface (1b) of the light guide plate (1) by an adhesive (not shown) made of a light transmitting resin.
However, since the fluorescent cover (8) is mounted in close contact with the light guide plate (1) via the light-transmitting resin adhesive layer, external force such as vibration is applied to the fluorescent cover (8) after mounting. Also, the fluorescent cover (8) does not easily come off the light guide plate (1). Further, by attaching the fluorescent cover (8) to the other main surface (1b) of the light guide plate (1) with a light-transmitting resin adhesive, a gap between the light guide plate (1) and the fluorescent cover (8) can be obtained. The air layer can be removed relatively easily and the luminous efficiency can be improved.

In this embodiment, the following operation and effect can be obtained. <1> Since the phosphor is added to the fluorescent cover (8) and not added to the resin sealing body (5) and the light guide plate (1), the fluorescent substance is added to the inside of the resin sealing body (5) and the light guide plate (1). There is no light scattering by the phosphor. <2> Also, since the light scattering by the phosphor is relatively small in the sufficiently thin film-like fluorescent cover (8),
A decrease in luminance due to wavelength conversion can be minimized. <3> The fluorescent cover (8) can extract light having a wavelength different from the light generated from a commercially available semiconductor light emitting device. <4> Change the type of phosphor in the fluorescent cover (8),
Light of various wavelengths can be extracted by changing the content of the phosphor in the fluorescent cover. <5> Since the fluorescent cover (8) is mounted in close contact with the light guide plate (1) via the adhesive layer of the light-transmitting resin, even if external force such as vibration is applied to the fluorescent cover (8) after mounting. The fluorescent cover (8) does not easily come off the light guide plate (1). The embodiments of the present invention can be modified. For example,
A plurality of phosphors are arranged in a plurality of islands, meshes, or grids throughout the resin substrate of the fluorescent cover (8), or the fluorescent cover (8) is formed with a large number of holes ( 8a), light of a desired mixed color or intermediate color or mixed color of wavelength-converted light and wavelength-unconverted light can be extracted. The opposing light emitting element assemblies (so that the optical axes of the semiconductor light emitting element (4) on one side of the light guide plate (1) and the semiconductor light emitting element (4) on the other side are displaced in the horizontal direction and alternate. The semiconductor light emitting element (4) of 2) may be arranged. When the semiconductor light emitting elements (4) are arranged staggered in this way, no light and dark portions are generated in the light guide plate (1),
Light can be emitted uniformly. The light emitting element assembly (2) may be provided only on one side surface (1c) of the light guide plate (1). Further, the light reflective film (7) may be stuck on the upper surface of the fluorescent cover (8).

[0020]

As described above, according to the present invention, it is possible to obtain a semiconductor planar light source which emits light of a high luminance intermediate color or mixed color.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor planar light source according to the present invention.

FIG. 2 is a plan view of a semiconductor planar light source according to the present invention.

FIG. 3 is a cross-sectional view of a semiconductor planar light source according to the present invention in which a fluorescent cover is formed in a mesh shape having many holes.

FIG. 4 is a plan view of a conventional semiconductor planar light source.

FIG. 5 is a side view of FIG. 4;

[Explanation of symbols]

(1) ··· Light guide plate, (1a) ··· One main surface, (1)
b) the other main surface, (1c) the side surface, (1d, 1
e) ··· Sloped surface, (1f) ··· Flat surface, (1g) ···
Recess, (2) light emitting element assembly, (3) printed circuit board, (4) semiconductor light emitting element, (5) resin encapsulation, (5a, 5b) inclined surface, 5c)
・ Flat surface, (6,7) ・ ・ Light reflective film,
(8) ・ ・ Fluorescent cover,

Continuing on the front page (72) Inventor Satoshi Honda 3-6-3 Kitano, Niiza City, Saitama Prefecture Within Sanken Electric Co., Ltd. (72) Inventor Hiroyuki Kawae 3-6-3 Kitano 3-6 Kitano, Niiza City, Saitama Prefecture Inside Electric Co., Ltd.

Claims (5)

[Claims] 1. A plate-shaped light guide plate (1), and the light guide plate (1)
A light emitting element assembly (2) attached to at least one side surface (1c) of the light guide plate; a light reflective film (6) fixed to one main surface (1a) of the light guide plate (1); A fluorescent cover (8) fixed to the other main surface (1b) of the light plate (1), wherein the light-emitting element assembly (2) is provided on a substrate (3) and an upper surface of the substrate (3); Plural fixed semiconductor light emitting devices (4)
And the substrate (3) covering the semiconductor light emitting device (4).
A plurality of resin sealing bodies (5) formed on the upper surface of the substrate and abutting on the side surface (1c), wherein the fluorescent cover (8) absorbs and absorbs light passing through the fluorescent cover (8). The semiconductor light-emitting element (4) contains a phosphor that emits light having a wavelength different from that of the light, and the light emitted from the semiconductor light-emitting element (4) is introduced into the light guide plate (1) from the side surface (1c). The light is directed into the fluorescent cover (8), and the wavelength is converted through the phosphor of the fluorescent cover (8) and emitted from the other main surface (1b) side of the light guide plate (1). Semiconductor planar light source. 2. The light guide plate (1) includes a plurality of recesses (1g) spaced apart from each other by a predetermined distance in a width direction, and the plurality of resin sealing bodies (5) are arranged in a width direction of the light guide plate (1). Are fixed to the substrate (3) at a predetermined distance from each other, and the semiconductor light emitting elements (4) are embedded in the corresponding resin sealing bodies (5), respectively. 2. The semiconductor planar light source according to claim 1, wherein the light guide plates are arranged in the corresponding recesses (1g) of the light guide plate (1). 3. Each of the recesses (1g) in the side surface (1c) of the light guide plate (1) is formed between the inclined surface (1d, 1e) and the adjacent inclined surface (1d, 1e). Flat surface (1
f), and each of the resin sealing bodies (5) has an inclined surface (5a, 5b) facing the inclined surface (1d, 1e) of the light guide plate (1).
And a flat surface (5c) formed between the inclined surfaces (5a, 5b) and facing the flat surface (1f) of the light guide plate (1).
The semiconductor planar light source according to claim 2, comprising: 4. The semiconductor according to claim 1, wherein said fluorescent cover (8) is fixed to said other main surface (1b) of said light guide plate (1) with an adhesive of a light transmitting resin. Surface light source. 5. The light emitting element assembly (2) on the side surface (1c) of the light guide plate (1) with an adhesive of a light transmitting resin.
The semiconductor planar light source according to any one of claims 1 to 4, wherein the resin sealing body (5) is fixed.