JP2006269364A - LED surface light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED surface light source device having a compact structure.
An LED surface light source device of the present invention includes a plurality of light guide plates having a wedge-shaped cross section formed by a horizontal upper emission surface and a slanted lower surface, and continuously arranged in a row. The plurality of LED array light sources 2 arranged along the thick side end face of each light guide plate, and arranged between the thick side end face of each light guide plate and each LED array light source, constitute each LED array light source A monochromatic light mixing member 4 that mixes monochromatic light emitted from an LED light source with different wavelengths and guides it to the end face on the thick side of each light guide plate, and the monochromatic light mixing member is in a direction perpendicular to the upper emission surface The LED array light source is disposed at a position offset in the vertical direction from the end surface on the thick side of the light guide plate.
[Selection] Figure 1

Description

  The present invention relates to an LED surface light source device, and more particularly, to an LED surface light source device that mixes monochromatic light from a plurality of LEDs (light emitting diodes) that emit monochromatic light of different wavelengths and uses it as white light.

  As a surface light source device for illumination of a display panel such as a liquid crystal panel, an LED surface light source device using a light emitting diode (LED) as a light source is known. In such an LED surface light source device, three types of LEDs that emit red (R), green (G), and blue (B) monochromatic light are used as a set, and the monochromatic light emitted from each LED is mixed. There is a type (hereinafter referred to as “RGB-LED surface light source device”) that produces white light.

  As such an RGB-LED surface light source device, an edge light system in which high-power LEDs are arranged in an array facing the end face of the light guide plate and light from the LEDs is incident on the end face of the light guide plate, a high output There is a direct method in which LEDs are two-dimensionally arranged directly below a diffusion plate and light is diffused by the diffusion plate. There has also been proposed a thin large surface light source in which wedge-shaped light guide plates are continuously arranged in a line, and a linear light source is disposed between the wedge light guide plates (see, for example, Patent Document 1).

JP 2001-312916 A

  The present invention has been made based on such a conventional technique.

  The RGB-LED surface light source device is a surface light source device that obtains white light by mixing three types of monochromatic light. Therefore, in order to mix monochromatic light, a predetermined mixing distance is provided downstream of the LED that is the monochromatic light source. It is necessary to secure.

  For this reason, in the edge light system, it is necessary to dispose the LED array light source away from the end face of the light guide plate in order to ensure a mixing distance, which increases the width of the display frame and increases the center of the display. This makes it difficult for light to reach the surface, and is not suitable for relatively large displays.

  On the other hand, in the direct method, the LED array light source is disposed rearward from the diffuser plate in order to ensure a mixing distance, which causes a problem that the display becomes thick. Some chip-type LEDs are encapsulated in a very small package, or one in which red, blue, and green LEDs are encapsulated in one package, and are connected in series. Light can be incident from a part of the end face of the light guide plate, but the allowable drive current is small and cannot be used as an actual large surface light source device. It is difficult to secure a sufficient mixing distance using a high drive current type LED that can be used for a large surface light source.

  The present invention has been made to solve such problems, and an object thereof is to provide an LED surface light source device having a compact structure.

  According to the present invention, a plurality of light guide plates having a wedge-shaped cross section constituted by a horizontal upper emission surface and an inclined lower side surface and continuously arranged in a row, and an end face on the thick side of each light guide plate A plurality of LED array light sources arranged along, a thick-side end face of each light guide plate and each LED array light source, and a wavelength emitted from the LED light sources constituting each LED array light source A monochromatic light mixing member that guides to the end face on the thick side of each of the light guide plates while mixing different monochromatic lights, and the monochromatic light mixing member has an inclined portion that is inclined with respect to a direction orthogonal to the upper emission surface. And an LED surface light source device characterized in that the LED array light source is disposed at a position offset in the vertical direction from the end surface on the thick side of the light guide plate.

  According to such a configuration, since the monochromatic light mixing member includes the inclined portion, the mixing distance is longer than the distance between the LED array light source and the end face on the thick side of the light guide plate. A long mixing distance can be ensured while suppressing the above. Further, mixing can be promoted by uniformly dispersing the diffusing agent in the monochromatic mixing member.

  According to another preferred aspect of the present invention, each of the LED array light sources includes a red LED that emits red monochromatic light, a green LED that emits green monochromatic light, and a blue LED that emits blue monochromatic light. Including.

  According to another preferred aspect of the present invention, the monochromatic light mixing member is located on the LED array light source side and extends in a direction perpendicular to the upper light exit surface of the light guide plate, and is located on the light guide plate side. And an exit portion that constitutes an inclined portion that extends with an inclination with respect to a direction orthogonal to the upper exit surface.

  According to another preferable aspect of the present invention, one end of the inclined portion is arranged to face the LED array light source, and the other end is connected to an end face on the thick side of the light guide plate.

  According to another preferred aspect of the present invention, the monochromatic light mixing member is located on the LED array light source side and extends in parallel with the upper exit surface of the light guide plate, and is located on the light guide plate side and the upper side. And an exit portion that constitutes an inclined portion that extends with an inclination with respect to a direction orthogonal to the exit surface.

  According to the LED surface light source device of the present invention, an LED surface light source device having a compact structure is provided.

Hereinafter, embodiments of the LED surface light source device of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of an LED surface light source device 1 according to a first embodiment of the present invention. As shown in FIG. 1, the LED surface light source device 1 has a so-called tandem configuration in which a plurality of surface light source device units 1a, 1b, and 1c having the same form are continuously arranged.

  Each surface light source device unit 1a, 1b, 1c is an LED that uses LEDs of a top emission type (including a type that emits light in a direction perpendicular to the light emitting surface and collimates with a lens) arranged in a row. An array light source 2 is provided. Each LED light source includes a plurality of red LEDs 2a that emit single-color red light, green LEDs 2b that emit green single-color light, and blue LEDs 2c that emit blue single-color light. Therefore, the LED surface light source device 1 of the present embodiment is an RGB-LED surface light source device.

  Each surface light source device unit 1 a, 1 b, 1 c further includes a monochromatic light mixing member 4 and a light guide plate 6. The monochromatic light mixing member 4 has a function of guiding monochromatic light having different wavelengths from the red LED 2a, green LED 2b, and blue LED 2c constituting the LED array light source 2 to the light guide plate 6 while mixing them.

The light guide plate 6 has a “wedge-shaped” cross-sectional shape including an upper emission surface 6 a arranged horizontally and a lower side surface 6 b inclined with respect to the upper emission surface 6 a. The side end surface 6c on the thick side of the light guide plate 6 is disposed so as to be inclined with respect to the direction orthogonal to the upper emission surface 6a. A row of LED array light sources 2 is arranged along the thick side end surface 6c with the monochromatic mixing member 4 interposed therebetween.
A prism portion 8 in which triangular prisms extending in the X direction in FIG. 1 are arranged in parallel is formed on the lower surface 6 b of the light guide plate 6. A silver vapor deposition reflection or white diffuse reflection plate 10 is disposed below the prism portion 8. Has been placed.

    The upper exit surface 6a of the light guide plate 6 is processed into a mat having a fine uneven shape on the mold by etching or blasting, and the mat 12 is transferred by injection molding. The average inclination angle of the mat 12 is about 2 to 6 °, and it is also possible to form a triangular casting prism extending in the Z direction corresponding to the angle. A prism sheet 14 is disposed above the mat 12. In the prism sheet 14, triangular prisms extending in the Z direction in FIG. 1 are arranged in parallel on the lower surface.

In the present embodiment, the mat surface formed on the light exit surface 6a of the light guide 6 has an average inclination angle θa in the range of 0.5 to 20 degrees to achieve a luminance uniformity within the light exit surface 6a. It is preferable from the point. This average inclination angle θa is more preferably in the range of 1 to 15 degrees, and more preferably in the range of 1.5 to 12 degrees. This is because when the average inclination angle θa of the mat surface is smaller than 0.5 degrees, the amount of light emitted from the light guide 6 tends to be small and sufficient luminance cannot be obtained, and when the average inclination angle θa is larger than 15 degrees. This is because a large amount of light is emitted in the vicinity of the end face, attenuation of the emitted light in the X direction within the emission surface 32 becomes significant, and the luminance uniformity on the emission surface 6a tends to decrease.
Thus, by setting the average inclination angle θa of the light guide 6 to 0.5 to 20 degrees, the angle of the peak light in the outgoing light luminous intensity distribution (in the XZ plane) of the light emitted from the outgoing face is the same as that of the light outgoing face. Light having a high directivity and having a directivity that is in the range of 50 to 80 degrees with respect to the normal line and the full width at half maximum of 10 to 40 degrees can be emitted from the light guide body 6, and the emission direction of the light is directed to the prism sheet. The surface light source device which can be efficiently deflected at 14 and has high luminance can be provided.

Here, the average inclination angle θa is measured in accordance with ISO 4287 / 1-1984 using a stylus type surface roughness meter, and the obtained inclination function f (x) is obtained by setting the coordinate in the measurement direction as x. To the following equations (1) and (2)
Δa = (1 / L) ∫ ₀ ^L | (d / dx) f (x) | dx (1)
θa = tan ⁻¹ (Δa) (2)
Can be obtained using Note that L is the measurement length, and Δa is the tangent of the average inclination angle θa.
In addition, as long as it is in the range of the said average inclination | tilt angle (theta) a instead of such a mat surface, it is good also as a lens surface which formed many lens rows extended in a Z direction. In this case, examples of the lens array to be formed include a prism array, a lenticular lens array, and a V-shaped groove.
The prism row formed on the lower surface 6b of the light guide 6 controls the directivity on the YZ plane of the light emitted from the light guide 6, and the apex angle is in the range of 85 to 110 degrees. It is preferable to do. This is because the light emitted from the light guide 6 can be appropriately condensed by setting the apex angle within this range, and the luminance as the planar light source device can be improved. Is in the range of 90-100 degrees.

In the present embodiment, the prism surface is formed with a large number of prism rows. However, lens rows other than the prism rows, such as lenticular lens rows and V-shaped grooves, may be formed so as to extend in the X direction. Moreover, you may form the top part or trough part, such as a prism row | line | column, in flat or a curved surface.
Further, in the present embodiment, a matte surface is formed on the exit surface 6a and a prism surface is formed on the lower surface 6b. Conversely, a prism surface is formed on the exit surface 6a, and the lower surface 6b is used as the mat surface. It may be a thing.

  Further, a minute amount of a diffusing agent is dispersed in the light guide body 6, and unevenness is provided on the 6 b surface as a mechanism for equalizing the emission amount of the light guide plate 6 in the XZ plane. Further, the diffusion film is formed on the light guide plate 6. Alternatively, a prism sheet in which triangular prisms extending in the Z direction are arranged in parallel may be arranged on the upper surface.

The monochromatic light mixing member 4 is positioned on the LED array light source 2 side and extends in a direction orthogonal to the upper emission surface 6 a of the light guide plate 6. The monochromatic light mixing member 4 is positioned on the light guide plate 6 side. And an inclined portion (outgoing portion) 4b extending obliquely with respect to the orthogonal direction.
The end surface 4c of the incident portion 4a of the monochromatic light mixing member 4 is disposed in parallel with the upper exit surface 6a of the light guide plate 6, and the LED array light source 2 is disposed to face the end surface 4c.
The end face 4 d of the emission part 4 b of the monochromatic light mixing member 4 is optically brought into close contact with the thick end face 6 c of the light guide plate 6. Here, “optically close” refers to a state where objects having optical transparency are in close contact with each other without forming an air layer therebetween.
As a result, the LED array light source 2 is disposed at a position offset in the vertical direction from the end surface 6 c on the thick side of the light guide plate 6.

  On the side surface 4e of the monochromatic light mixing member 4, a silver vapor-deposited reflective film or a white diffuse reflective film 16 is disposed as a reflective material.

  The monochromatic light mixing member 4 and the light guide plate 6 are formed of a transparent resin such as PMMA (polymethyl methacrylate). In this embodiment, the light guide plate 6 is set such that the length L of the upper surface 6a is 150 mm, the maximum thickness d1 is 2.2 mm, and the minimum thickness d2 is 0.7 mm. However, the present invention is not limited to this. It is not a thing. The width of the 4c surface of the monochromatic light mixing member 4 depends on the lens shape of the LED light source and the distance to the monochromatic light mixing member, but is set to 5.0 mm.

  The monochromatic light mixing member 4 and / or the light guide plate 6 may be configured to contain a diffusing agent and diffuse the light transmitted through the inside to promote mixing. Further, the end surface 4c of the incident portion 4a and the end surface 4d of the output portion 4b of the monochromatic light mixing member 4 may be processed into a mat or prism shape.

Next, the operation of the LED surface light source device 1 according to the first embodiment will be described.
As indicated by arrows in FIG. 1, the monochromatic light emitted upward from the light emitting portion 3 of each LED 2 a, 2 b, 2 c enters the monochromatic light mixing member 4 from the end face 4 c of the incident portion 4 a of the monochromatic light mixing member 4. . The monochromatic light incident on the monochromatic light mixing member 4 is reflected by the reflective film 16 and mixed while propagating through the monochromatic light mixing member 4 to become white light.

  White light enters the light guide plate 6 from the end surface 4 d of the emission part 4 b of the monochromatic light mixing member 4 through the thick end surface 6 c of the light guide plate 6, and propagates inside the light guide plate 6. The white light is reflected by the prism 8 formed on the lower side 6 b of the light guide plate 6 and the reflection plate 10 provided below the light, and is deflected in the direction of the upper emission surface 6 a of the light guide plate 6. The light exceeding the critical angle exits from the upper exit surface 6a. The prism sheet 14 deflects the light in the direction orthogonal to the upper exit surface 6a.

  According to the LED surface light source device 1 of the present embodiment described above, the monochromatic light mixing member that mixes (mixes) monochromatic light into white light is inclined with respect to the direction orthogonal to the upper emission surface 6 a of the light guide plate 6. And an inclined portion (exit portion) 4b extending. That is, since a part of the monochromatic light mixing member is arranged to be inclined with respect to the thickness direction of the surface light source device, the position where the LED array light source 2 is offset in the vertical direction from the end surface on the thick side of the light guide plate It is possible to use a high-power LED with a large package and to take a long mixing length sufficient to produce white. Therefore, the thickness of the LED surface light source device can be suppressed.

  Further, each monochromatic light emitted from each LED 2 a, 2 b, 2 c is efficiently mixed by the monochromatic light mixing member 4 and becomes white light. It can radiate | emit uniformly from the whole from the upper output surface 6a.

Next, an LED surface light source device according to a second embodiment of the present invention will be described.
FIG. 2 is a schematic cross-sectional view showing the configuration of the LED surface light source device 20 according to the second embodiment of the present invention. As shown in FIG. 2, the LED surface light source device 20 of the second embodiment basically has the same configuration as the LED surface light source device 1 of the first embodiment. Therefore, in FIG. 2, the same parts as those in FIG.

The differences between the LED surface light source device 20 of the second embodiment and the LED surface light source device 1 of the first embodiment are the light emission direction from the LED array light source 2 and the shape of the monochromatic light mixing member.
As shown in FIG. 2, the LED surface light source device 20 is a top emission type used in the LED surface light source device 1 of the first embodiment (a type that emits light in a direction perpendicular to the light emitting surface and is collimated by attaching a lens). LED array light source 22 using a side emission type LED (a type that emits light in a direction horizontal to the light emitting surface) is used instead of LED array light source 2 using LEDs.

  In the LED surface light source device 20, a monochromatic light mixing member 24 having a trapezoidal cross-sectional shape is used. In the LED surface light source device 20, the monochromatic light mixing member 24 is disposed so as to be inclined and extend with respect to a direction orthogonal to the upper emission surface 6 a of the light guide plate 6. In addition, the trapezoidal monochromatic light mixing member 24 has a lower base 24 a disposed so as to face the LED array light source 22, and an upper base 24 b optically attached to the end face 6 c on the thick side of the light guide plate 6.

Each LED array light source 22 includes a red LED 22a that emits red monochromatic light, a green LED 22b that emits green monochromatic light, and a blue LED 22c that emits blue monochromatic light. The light emitting portion 23 of each LED array light source 22 uses an LED module having a lens design that emits monochromatic light toward the side (in a direction horizontal to the light emitting surface) as indicated by arrows in FIG. Yes.
Each LED array light source 22 is configured so that the emitted monochromatic light is incident on the lower base 24b of the monochromatic light mixing member 24 disposed to be inclined with respect to the direction orthogonal to the upper emission surface 6a of the light guide plate 6 from a substantially vertical direction. (Fig. 2). A reflector 25 is disposed on the back and top surfaces of the LED array light source 22.
As a result, the rows of the LED array light sources 22 are arranged at positions offset in the vertical direction from the end surface 6 c on the thick side of the light guide plate 6.

  According to the LED surface light source device 20 of the present embodiment described above, the monochromatic light mixing member that mixes (mixes) monochromatic light into white light is inclined with respect to the direction orthogonal to the upper emission surface 6 a of the light guide plate 6. Therefore, the LED array light source 2 can be arranged at a position offset in the vertical direction from the end surface on the thick side of the light guide plate, and a long mixing length sufficient to make white is used by using a large high-power LED of the package. It becomes possible to take. Therefore, the thickness of the LED surface light source device can be suppressed.

Next, an LED surface light source device according to a third embodiment of the present invention will be described.
FIG. 3 is a schematic cross-sectional view showing the configuration of the LED surface light source device 30 according to the third embodiment of the present invention. As shown in FIG. 3, the LED surface light source device 30 of the third embodiment basically has the same configuration as the first LED surface light source device 1. Therefore, in FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

The difference between the LED surface light source device 30 of the third embodiment and the LED surface light source device 1 of the first embodiment is the direction of the LED array light source and the shape of the monochromatic light mixing member.
As shown in FIG. 3, the monochromatic light mixing member 34 of the LED surface light source device 20 is positioned on the LED array light source side and extends in parallel with the upper exit surface 6 a of the light guide plate 6, and is positioned on the light guide plate 6 side. And an inclined portion (exit portion) 34b extending obliquely with respect to the direction orthogonal to the upper exit surface 6a.

  Further, as the LED array light source 32, an LED array light source 32 using a top emission type LED (including a type that emits light in a direction perpendicular to the light emitting surface and that collimates with a lens) as in the first embodiment. Is used. The LED array light source 32 is configured so that the monochromatic light emitted upward from the LED from the light emitting portion 33 of each LED constituting the LED array vertically enters the end surface 34c of the incident portion 34 extending in the direction orthogonal to the upper emission surface 6a. , 90 degrees tilted. Further, the monochromatic light mixing member 34 includes an inclined portion (emission portion) 34 b extending inclined with respect to a direction orthogonal to the upper emission surface 6 a of the light guide plate 6. As a result, the row of LED array light sources 32 is arranged at a position offset in the vertical direction from the end surface 6 c on the thick side of the light guide plate 6.

  That is, since a part of the monochromatic light mixing member is arranged to be inclined with respect to the thickness direction of the surface light source device, the position where the LED array light source 2 is offset in the vertical direction from the end surface on the thick side of the light guide plate It is possible to use a high-power LED with a large package and to take a long mixing length sufficient to produce white. Therefore, the thickness of the LED surface light source device can be suppressed.

  The present invention is not limited to the above-described embodiment, and various changes and modifications can be made within the scope of the technical idea described in the claims.

It is sectional drawing which shows roughly the structure of the LED surface light source device by 1st Embodiment of this invention. It is a schematic sectional drawing similar to FIG. 1 which shows the LED surface light source device of 2nd Embodiment of this invention. It is a schematic sectional drawing similar to FIG. 1 which shows the LED surface light source device of 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,20,30 LED surface light source device 2,22,32 LED array light source 4,24,34 Monochromatic light mixing member 6 Light guide plate 8 Prism 10 Reflector 12 Mat 14 Prism sheet 16 Silver vapor deposition film or white diffuse reflection film 25 LED Light source reflector

Claims (5)

A plurality of light guide plates continuously arranged in a line with a wedge-shaped cross section constituted by a horizontal upper emission surface and an inclined lower side surface;
A plurality of LED array light sources disposed along the end face on the thick side of each light guide plate;
The light guide plate is disposed between the end face on the thick side of each light guide plate and each LED array light source, and mixed with monochromatic light having different wavelengths emitted from the LED light sources constituting each LED array light source. A monochromatic light mixing member that leads to the end face on the thick side,
The monochromatic light mixing member includes an inclined portion extending inclined with respect to a direction orthogonal to the upper emission surface,
The LED array light source is disposed at a position offset in the vertical direction from the end face on the thick side of the light guide plate,
An LED surface light source device. The LED surface light source device according to claim 1, wherein each of the LED array light sources includes a red LED that emits red monochromatic light, a green LED that emits green monochromatic light, and a blue LED that emits blue monochromatic light. . The monochromatic light mixing member is located on the LED array light source side and extends in a direction perpendicular to the upper light emitting surface of the light guide plate, and the direction located on the light guide plate side and perpendicular to the upper light emitting surface An exit portion that constitutes an inclined portion extending in an inclined manner,
The LED surface light source device according to claim 1 or 2. One end of the inclined portion is arranged to face the LED array light source, and the other end is connected to the end surface on the thick side of the light guide plate.
The LED surface light source device according to claim 1 or 2. The monochromatic light mixing member is located on the LED array light source side and extends in parallel with the upper light exit surface of the light guide plate, and is inclined with respect to a direction located on the light guide plate side and perpendicular to the upper light exit surface. An exit portion constituting an extending inclined portion,
The LED surface light source device according to claim 1 or 2.

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