JP4430571B2 - LED surface light source device - Google Patents

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.

  An LED surface light source device using a light emitting diode (LED) as a light source is known as a backlight for illumination of a display panel such as a liquid crystal panel. 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 immediately below the diffusion plate and light is diffused by the diffusion plate.

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

  The RGB-LED surface light source device is a backlight that obtains white light by mixing three types of single-color light. Therefore, to mix the single-color light, a predetermined mixing distance is secured downstream of the LED that is the single-color light source. There is a need to.

  For this reason, in the edge light system, it is necessary to dispose the LED light source outward from the edge of the light guide plate in order to ensure a mixing distance, and the width of the display frame becomes wide and the center of the display reaches The problem is that light is difficult to reach and is not suitable for relatively large displays.

  On the other hand, in the direct system, the LED light source is disposed rearward from the diffuser plate in order to ensure a mixing distance, so that the display becomes thick.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide an LED surface light source device having a compact structure while ensuring a sufficient mixing distance.

  According to the present invention, an LED array light source group composed of LED modules that are configured by LED modules that emit monochromatic light of different wavelengths in a horizontal direction with respect to a light emitting surface is arranged horizontally, and arranged horizontally. A wedge-shaped cross-sectional shape having a top surface and a bottom surface inclined with respect to the top surface, and the end surface on the thick side faces the LED array light sources via the first monochromatic light mixing member. A wedge-shaped cross-sectional shape having a first light guide plate disposed in a horizontal direction, a lower surface disposed horizontally, and an upper surface disposed to be inclined with respect to the lower surface, and opposite to the first light guide plate And a second light guide plate having a thick-side end face opposed to each LED array light source via a second monochromatic light mixing member, and above the LED light source and the first and second monochromatic light mixing members A light shielding member disposed on the The light guide plate is disposed inclined lower surface, the LED surface light source device, characterized in that the second is configured to tilt the light guide plate to be parallel to the arranged upper surface is provided.

  According to such a configuration, the LED light source (or LED array light source) is arranged between the light guide plates, and the monochromatic light of different wavelengths from the LED light source passes through the monochromatic light mixing member and then from the end surface. The light enters the first or second light guide plate. That is, the monochromatic light is mixed while traveling in the direction along the surface of the light guide plate in the monochromatic light mixing member, and enters the light guide plate from the side. Therefore, it is possible to take a sufficient mixing distance while suppressing an increase in the thickness of the surface light source device. Further, it is possible to efficiently enter LED light of a type that emits light in all horizontal directions with respect to the light emitting surface.

  According to another preferred aspect of the present invention, the LED 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.

  According to another preferable aspect of the present invention, the light guide device further includes a light diffusing unit that covers an upper surface of the first light guide plate, and a light reflection unit that covers a lower surface of the second light guide plate.

  According to another preferred aspect of the present invention, there is provided a light deflecting unit that is disposed on the light diffusing unit and deflects the light diffused by the light diffusing unit in a direction orthogonal to the upper surface of the first light guide plate. ing.

  According to the LED surface light source device of the present invention, it is an object to provide an LED surface light source device having a compact structure while ensuring a sufficient mixing distance.

Hereinafter, an LED surface light source device according to an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view schematically showing the structure of an LED surface light source device 1 according to an embodiment of the present invention. As shown in FIG. 1, the LED surface light source device 1 includes an LED array light source constituted by a number of LED light sources 2, an upper surface 4 a disposed horizontally, and a lower surface 4 b disposed inclined with respect to the upper surface 4 a. A wedge-shaped cross-sectional shape including a first light guide plate 4 having a wedge-shaped cross-sectional shape, and a lower surface 6a disposed horizontally and an upper surface 6b disposed inclined with respect to the lower surface 6a. A second light guide plate 6 disposed on the opposite side of the first light guide plate 4 across the LED array light source is provided.

Each LED light source 2 includes a red LED 2a that emits red monochromatic light, a green LED 2b that emits green monochromatic light, and a blue LED 2c that emits blue monochromatic light. Each monochromatic light LED is a side emission type LED in which most of the light is emitted in the horizontal direction with respect to the light emitting surface. As an example of LED, there is a side emitter type of Luxeon Emitter of Lumileds.
A large number of LED light sources 2 are arranged in a row extending in the Z direction in FIG. 1, and constitute an LED array light source. The LED surface light source device 1 has a so-called tandem configuration in which such LED array light sources are arranged in parallel at predetermined intervals.

  The first light guide plate 4 is disposed such that the thick end surface 4 c faces one side surface of each LED array light source 2 via the first monochromatic light mixing member 8. On the other hand, the second light guide plate 6 is disposed so that the thick end surface 6 c faces the other side surface of each LED array light source 2 via the second monochromatic light mixing member 10.

  As shown in FIG. 1, the first and second light guide plates 4, 6 are arranged with an inclined lower surface 4 b of the first light guide plate 4 and an inclined second light guide plate 6 adjacent thereto. The upper surface 6b is disposed in parallel with the air layer 12 having a constant thickness. The light guide plates 4 and 6 contain a small amount of diffusing agent. In this embodiment, about 0.5 to 10 ppm of titanium oxide particles are dispersed.

  In each monochromatic light mixing member 8, 10, the LED array light source and the thick side end surfaces 4 c, 6 c of the first and second light guide plates 4, 6 have the same width (length in the Z direction in FIG. 1), Further, the length of the monochromatic light having different wavelengths from the red LED 2a, the green LED 2b, and the blue LED 2c constituting the LED light source 2 is mixed and then incident on the first or second light guide plates 4 and 6 (in the X direction in FIG. 1). Length).

One side surface 8 a of the first monochromatic light mixing member 8 is optically adhered to the thick side surface 4 c of the first light guide plate 4. Further, the other side surface 8 b of the first monochromatic light mixing member 8 is disposed adjacent to one side surface of each LED array light source 2 so as to face each other.
On the other hand, one side surface 10 a of the second monochromatic light mixing member 10 is optically brought into close contact with the thick side surface 6 c of the second light guide plate 6. Further, the other side surface 10 b of the second monochromatic light mixing member 10 is disposed so as to be adjacent to and opposed to the other side surface of each LED array light source 2.

  The first and second light guide plates 4 and 6 and the first and second monochromatic light mixing members 8 and 10 are all made of a transparent resin such as PMMA (polymethyl methacrylate). Furthermore, the first and second monochromatic light mixing members 8 and 10 contain more light diffusing material than the light guide plates 4 and 6. In this embodiment, about 1 to 100 ppm of titanium oxide particles are dispersed.

  The LED surface light source device 1 further includes a reflective (light-shielding) film 14 disposed so as to cover the LED array light source and the first and second monochromatic light mixing members 8 and 10, and both surfaces are silver-deposited or white diffused. It is a reflection and has a strong light shielding effect on the back surface.

  In the LED surface light source device 1 of the present embodiment, a diffusion film and a diffusion sheet 16 are disposed so as to cover the entire surface light source. The diffusion sheet 16 has a function of making the joints of the light guide plates inconspicuous and deflecting light in a direction perpendicular to the 4a surface of the light guide plate 4. Further, on the diffusion sheet, an upward prism sheet 18 in which triangular prisms extending in the Z direction in FIG. 1 are arranged in parallel is disposed.

  Further, a silver vapor deposition reflection or white diffuse reflection plate 22 is disposed on the lower surface 6 a of the second light guide plate 6.

Next, the operation of the LED surface light source device 1 will be described.
Of the monochromatic light emitted toward the side as indicated by the arrows from the monochromatic colors 2a, 2b, and 2c constituting each LED light source 2, the component toward the thick end surface 4c of the first light guide plate 4 is the first component. The light enters the first monochromatic light mixing member 8 from the other end face 8 b of the monochromatic light mixing member 8. The incident monochromatic light is mixed into white light while propagating through the first monochromatic light mixing member 8 toward the first light guide plate 4. Next, the light enters the first light guide plate 4 from the thick end surface 4 c of the first light guide plate 4. While propagating through the monochromatic light mixing member 8, the component that attempts to escape upward is reflected by the reflecting material 14, and the component that attempts to escape downward is reflected by the reflecting plate 22 and returned to the first monochromatic light mixing member 8.

  Of the white light that enters the first light guide plate 4 and propagates through it, the light that exceeds the critical angle determined by the refractive index of the light guide plate 4 and air is sequentially emitted from the upper surface 4a of the first light guide plate 4. Further, the light is further diffused by the diffusion film or diffusion sheet 16 on the surface 4a, and is deflected by the upward prism sheet 18 in the direction orthogonal to the upper surface 4a, that is, the front direction of the LED surface light source device 1.

  On the other hand, the component toward the thick end surface 6 c of the second light guide plate 6 enters the first monochromatic light mixing member 10 from the other end surface 10 b of the second monochromatic light mixing member 10. The incident monochromatic light is mixed into white light while propagating in the second monochromatic light mixing member 10 toward the second light guide plate 6. Next, the light enters the second light guide plate 6 from the thick end surface 6 c of the second light guide plate 6. While propagating through the monochromatic light mixing member 10, the component that attempts to escape upward is reflected by the reflecting material 14, and the component that attempts to escape downward is reflected by the reflecting plate 22 and returned to the second monochromatic light mixing member 10. .

  Of the white light that has propagated through the second light guide plate 6 and reached the surface 6a, the light that exceeds the critical angle determined by the refractive index of the light guide plate 6 and air passes through the air layer 12 and passes through the first light guide plate. 4 is incident. Further, the white light passes through the first light guide plate 4 and is emitted from the upper surface 4 a of the first light guide plate 4. The air layer 12 may be filled with a low refractive index resin.

    According to the LED surface light source device 1 of the present embodiment described above, each monochromatic light emitted from each of the LEDs 2a, 2b, 2c passes through the first and second monochromatic light mixing members in the lateral direction (in the final emission direction). Mixing while propagating in the orthogonal direction. Therefore, it is possible to take a sufficient mixing distance while suppressing the thickness of the surface light source (length along the emission direction). Further, it is possible to efficiently enter LED light of a type that emits light in all horizontal directions with respect to the light emitting surface.

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.
The LED surface light source device 1 of the above embodiment has a configuration in which the monochromatic light mixing member is separated from the light guide plate. However, the upper end of the light guide plate is covered with a light shielding material or the like, and this end is monochromatic light. The structure utilized as a mixing member may be sufficient.

  Further, the LED surface light source device 1 of the above-described embodiment has a configuration in which one prism sheet 18 is disposed above the diffusion film or the diffusion sheet 16, but the direction orthogonal to the prism of the prism sheet 18 (X direction). Alternatively, a prism sheet extending in the prism may be disposed above the prism sheet 18.

It is sectional drawing which shows roughly the structure of the LED surface light source device of one Embodiment of this invention.

Explanation of symbols

1 LED surface light source device 2 LED array light source 4 first light guide plate 4a (first light guide plate) upper surface 4b (first light guide plate) lower surface 4c (first light guide plate) thicker end surface 6 second light guide plate 6a Upper surface 6b (of the second light guide plate) Lower surface 6c (of the second light guide plate) End surface 8 on the thick side (of the second light guide plate) First monochromatic light mixing member 8a One end surface 8b (of the first monochromatic light mixing member) The other end face 10 (of the first monochromatic light mixing member) The second end face 10b (of the second monochromatic light mixing member) One end face 10b (of the second monochromatic light mixing member) The other end face 14 of the second monochromatic light mixing member Element)

Claims (4)

An LED array light source group in which LED array light sources composed of LED modules that emit monochromatic light of different wavelengths in a horizontal direction with respect to the light emitting surface are arranged in parallel at a predetermined interval;
Each of the LED arrays has a wedge-shaped cross-sectional shape including a horizontally disposed upper surface and a lower surface disposed to be inclined with respect to the upper surface, and a thick-side end surface via a first monochromatic light mixing member A first light guide plate disposed facing the light source;
A wedge-shaped cross-sectional shape having a horizontally arranged lower surface and an upper surface inclined with respect to the lower surface, and an end surface on the thick side opposite to the first light guide plate is a second monochromatic color A second light guide plate disposed facing the LED array light sources via a light mixing member;
A light shielding and reflecting member disposed above the LED light source and the first and second monochromatic light mixing members;
The first light guide plate is configured such that a lower surface disposed at an inclination is parallel to an upper surface disposed at an inclination of the second light guide plate.
An LED surface light source device. The LED 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 LED surface light source device according to claim 1. Light diffusing means for covering the upper surface of the first light guide plate;
A light reflecting means for covering the lower surface of the second light guide plate;
The LED surface light source device according to claim 1 or 2. A light deflecting unit disposed on the light diffusing unit and deflecting the light diffused by the light diffusing unit in a direction perpendicular to the upper surface of the first light guide plate;
The LED surface light source device according to any one of claims 1 to 3.

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