JP2006093015A - Flat lighting device and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve luminance while cumulative thickness of a diffuser and a prism sheet is not thicker than thickness of a light source device, a light shield does not stick to the surface part of the light guide plate other than an effective emission region of the light guide plate even if the light shield is pasted on a top part and either luminance deviation nor a luminance spot occurs. <P>SOLUTION: The light guide plate 4 is formed so that a flat surface part which serves the effective emission region L is thinner than the height of the light source device 5. The diffuser 6 disposed over the light guide plate 4 is formed longer than the effective emission region L of the light guide plate 4 in a direction from a reflection end-face part 4e to an incidence end-face part 4c. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, among the diffuser and prism sheet provided on the effective emission area of the light guide plate, the diffuser provided immediately above the light guide plate is lengthened from the reflection end surface portion of the light guide plate toward the incident end surface portion. The accumulated thickness of the light plate, diffuser, and prism sheet does not become thicker than the thickness of the light source, and even if a light shield is attached to the top of these, the light shield is not on the surface of the light guide plate outside the effective emission area of the light guide plate. The present invention relates to a flat illumination device that does not stick, does not generate luminance deviation or luminance unevenness, and can further improve luminance, and a liquid crystal display device using the flat illumination device.

As a conventional liquid crystal display device or flat illumination device, a diffuser (diffusion sheet), a prism sheet, a light shielding sheet, and a liquid crystal display are placed in this order toward the upper side of the light guide plate. And a size equal to the size including the light source disposed in close proximity to or in close proximity to the light guide plate and the incident end face portion of the light guide plate are known.
Japanese Patent Laid-Open No. 2002-296569

  In the above-described conventional liquid crystal display device and flat illumination device, since the height of the light source and the thickness of the light guide plate are equal, the diffuser (diffusion sheet) and the prism sheet placed above the light guide plate rather than the height of the light source Therefore, there is a problem that the flat lighting device becomes thicker by the accumulated thickness.

  Further, when the height of the light source is set to the maximum thickness (height), the diffuser (diffusion sheet) placed on the light guide plate and the prism sheet are accumulated on the thickness of the light guide plate. Difficult to be equal to the height of the light source. In addition, since the light source is higher (thick) than other cumulative heights, the light-shielding sheet cannot be applied flatly, which may cause wrinkles and the like, and there is a problem with respect to the generation of luminance and spots.

  Furthermore, the light guide plate has a wedge shape, and the thickness (height) of the incident end surface, which is the maximum height (maximum thickness) of the light guide plate, is made equal to the thickness (height) of the light source. When the thickness (height) of the diffuser (diffusion sheet) and the prism sheet is made to coincide with each other in the wedge-shaped taper portion, when the light shielding sheet is pasted, the light shielding sheet becomes the diffuser of the light guide plate and the prism. There is a problem that the sheet is stuck on the surface portion of the part where the sheet is not placed, a decrease in luminance or a luminance deviation occurs, or a variation in which the flat illumination device varies with respect to the luminance or the like.

  The present invention has been made to solve the above-described problems. A light source, an incident end surface portion that guides light from the light source, a reflection end surface portion positioned opposite to the incident end surface portion, and an output that emits light. A light guide plate comprising a surface and a back surface located opposite to the output surface; a diffuser that diffuses light emitted from the light guide plate; a prism sheet that condenses light emitted from the diffuser; and a prism sheet A light shielding body provided above, and a case for housing the light source, the light guide plate, the diffuser, the prism sheet, and the light shielding body. By making the diffuser immediately above the optical plate longer in the direction of the incident end surface from the reflection end surface of the light guide plate, the accumulated thickness of these light guide plate, diffuser and prism sheet does not become thicker than the thickness of the light source, Shading on top of these Even if it sticks, the light-shielding body does not stick to the surface of the light guide plate outside the effective emission area of the light guide plate, and no luminance deviation or luminance unevenness occurs, and the flat illumination device and the flat illumination device that can further improve the luminance An object of the present invention is to provide a liquid crystal display device using the above.

A flat illumination device according to claim 1 of the present invention includes a light source,
A light guide plate composed of an incident end face part that guides light from the light source, a reflection end face part located opposite to the incident end face part, an exit face that emits light, and a back face part located opposite to the exit face;
A diffuser that diffuses light emitted from the light guide plate;
A prism sheet that collects light emitted from the diffuser, and the like;
A light-shielding body provided above the prism sheet;
Including at least a light source, a light guide plate, a diffuser, a prism sheet, and a light shielding body;
In the light guide plate, at least the flat surface portion forming the effective emission area is thinner than the height of the light source,
The diffuser is made longer from the reflection end surface portion toward the incident end surface portion than the effective emission region of the light guide plate above the light guide plate.

The flat illumination device according to claim 1 includes a light source,
A light guide plate composed of an incident end face part that guides light from the light source, a reflection end face part located opposite to the incident end face part, an exit face that emits light, and a back face part located opposite to the exit face;
A diffuser that diffuses light emitted from the light guide plate;
A prism sheet that collects light emitted from the diffuser, and the like;
A light-shielding body provided above the prism sheet;
Including at least a light source, a light guide plate, a diffuser, a prism sheet, and a light shielding body;
In the light guide plate, at least the flat surface portion forming the effective emission area is thinner than the height of the light source,
Since the diffuser is made longer above the light guide plate in the direction from the reflection end face to the incident end face than the effective emission area of the light guide plate, the diffuser provided on the effective emission area of the light guide plate and the light guide plate and the prism sheet The accumulated thickness does not become thicker than the thickness of the light source, and even if a light shield is attached to the top of these, the light shield does not stick to the surface portion of the light guide plate outside the effective emission area of the light guide plate, and luminance deviation or brightness Spots are not generated and the luminance can be further improved.

A liquid crystal display device according to claim 2 is a liquid crystal display body;
A light source;
It consists of an incident end face for guiding light from the light source, a reflection end face located opposite to the incident end face, an exit face for emitting light toward the liquid crystal display, and a back face located opposite to the exit face. A light guide plate;
A diffuser that diffuses light emitted from the light guide plate;
A prism sheet that collects light emitted from the diffuser, and the like;
A light-shielding body provided above the prism sheet;
Including at least a light source, a light guide plate, a diffuser, a prism sheet, and a light shielding body;
In the light guide plate, at least the flat surface portion forming the effective emission area is thinner than the height of the light source,
The diffuser is made longer from the reflection end surface portion toward the incident end surface portion than the effective emission region of the light guide plate above the light guide plate.

A liquid crystal display device according to claim 2 comprises a liquid crystal display body,
A light source;
It consists of an incident end face for guiding light from the light source, a reflection end face located opposite to the incident end face, an exit face for emitting light toward the liquid crystal display, and a back face located opposite to the exit face. A light guide plate;
A diffuser that diffuses light emitted from the light guide plate;
A prism sheet that collects light emitted from the diffuser, and the like;
A light-shielding body provided above the prism sheet;
Including at least a light source, a light guide plate, a diffuser, a prism sheet, and a light shielding body;
In the light guide plate, at least the flat surface portion forming the effective emission area is thinner than the height of the light source,
Since the diffuser is made longer above the light guide plate in the direction from the reflection end face to the incident end face than the effective emission area of the light guide plate, the diffuser provided on the effective emission area of the light guide plate and the light guide plate and the prism sheet The accumulated thickness does not become thicker than the thickness of the light source, and even if a light shield is attached to the top of these, the light shield does not stick to the surface portion of the light guide plate outside the effective emission area of the light guide plate, and luminance deviation or brightness Spots are not generated and the luminance can be further improved.

  Furthermore, the flat illumination device according to claim 3 and the liquid crystal display device according to claim 7 are characterized in that the light guide plate has an incident end face portion substantially equal to the height of the light source.

In the flat illumination device according to claim 3 and the liquid crystal display device according to claim 7, since the light guide plate has an incident end face portion substantially equal to the height of the light source, the effective emission region is obtained when the thickness of the light guide plate is uniform. A large shading can be taken and a light-shielding body can be pasted without distortion.
When the light guide plate has a wedge shape, the prism sheet can be accommodated in the effective emission area, and the diffuser can be accommodated outside the effective emission area inside the incident end face. For this reason, it does not become the height of the light source finally, and the light shielding body does not stick to the surface portion of the light guide plate outside the effective emission region.

  Further, in the flat illumination device according to claim 4 and the liquid crystal display device according to claim 8, the prism sheet is substantially equal to the effective emission region in the length direction from the reflection end surface portion to the incident end surface portion of the light guide plate. Features.

  In the flat illumination device according to claim 4 and the liquid crystal display device according to claim 8, the prism sheet is substantially equal to the effective emission region in the length direction from the reflection end surface portion to the incident end surface portion of the light guide plate. Light emitted from the region can be sufficiently condensed. For example, when the light guide plate has a wedge shape, the prism sheet can be accommodated in the effective emission region, so that it does not become thicker than the incident end surface portion of the light guide plate.

  Furthermore, the flat illumination device according to claim 5 and the liquid crystal display device according to claim 9 are characterized in that the diffuser is substantially equal to the length from the incident end surface portion to the reflection end surface portion of the light guide plate.

  In the flat illumination device according to the fifth aspect and the liquid crystal display device according to the ninth aspect, since the diffuser is substantially equal to the length from the incident end surface portion to the reflective end surface portion of the light guide plate, the incident end surface of the light guide plate and the light source Even at a place substantially equal to the height, it does not exceed the height of the light source, and the light shielding body can be prevented from sticking at places other than the effective emission region of the light guide plate.

  The flat illumination device according to claim 6 and the liquid crystal display device according to claim 10 are characterized in that the light shield has an opening in an effective emission region of the light guide plate and has a size equal to or greater than that of the light guide plate. To do.

In the flat illumination device according to claim 6 and the liquid crystal display device according to claim 10, the light shield has an opening in the effective emission region of the light guide plate and has a size equal to or greater than that of the light guide plate. When the length is equal to the length of the light guide plate, light leakage from the vicinity of the light source position can be blocked.
Moreover, when the light shielding body is longer than the length of the light guide plate, it is possible to block light leakage and outgoing light from places other than the effective light emission region of the light guide plate.

The flat illumination device according to claim 1 includes a light source,
A light guide plate composed of an incident end face part that guides light from the light source, a reflection end face part located opposite to the incident end face part, an exit face that emits light, and a back face part located opposite to the exit face;
A diffuser that diffuses light emitted from the light guide plate;
A prism sheet that collects light emitted from the diffuser, and the like;
A light-shielding body provided above the prism sheet;
Including at least a light source, a light guide plate, a diffuser, a prism sheet, and a light shielding body;
In the light guide plate, at least the flat surface portion forming the effective emission area is thinner than the height of the light source,
Since the diffuser is made longer above the light guide plate in the direction from the reflection end face to the incident end face than the effective emission area of the light guide plate, the diffuser provided on the effective emission area of the light guide plate and the light guide plate and the prism sheet The accumulated thickness does not become thicker than the thickness of the light source, and even if a light shield is attached to the top of these, the light shield does not stick to the surface portion of the light guide plate outside the effective emission area of the light guide plate, and luminance deviation or brightness Spots are not generated and the luminance can be further improved.

A flat illumination device according to claim 2 is a liquid crystal display,
A light source;
It consists of an incident end face for guiding light from the light source, a reflection end face located opposite to the incident end face, an exit face for emitting light toward the liquid crystal display, and a back face located opposite to the exit face. A light guide plate;
A diffuser that diffuses light emitted from the light guide plate;
A prism sheet that collects light emitted from the diffuser, and the like;
A light-shielding body provided above the prism sheet;
Including at least a light source, a light guide plate, a diffuser, a prism sheet, and a light shielding body;
In the light guide plate, at least the flat surface portion forming the effective emission area is thinner than the height of the light source,
Since the diffuser is made longer above the light guide plate in the direction from the reflection end face to the incident end face than the effective emission area of the light guide plate, the diffuser provided on the effective emission area of the light guide plate and the light guide plate and the prism sheet The accumulated thickness does not become thicker than the thickness of the light source, and even if a light shield is attached to the top of these, the light shield does not stick to the surface portion of the light guide plate outside the effective emission area of the light guide plate, and luminance deviation or brightness Spots are not generated and the luminance can be further improved.

In the flat illumination device according to claim 3 and the liquid crystal display device according to claim 7, since the light guide plate has an incident end face portion substantially equal to the height of the light source, the effective emission region is obtained when the thickness of the light guide plate is uniform. A large shading can be taken and a light-shielding body can be pasted without distortion.
When the light guide plate has a wedge shape, the prism sheet can be accommodated in the effective emission area, and the diffuser can be accommodated outside the effective emission area inside the incident end face. For this reason, it does not become the height of the light source finally, and the light shielding body does not stick to the surface portion of the light guide plate outside the effective emission region.

  In the flat illumination device according to claim 4 and the liquid crystal display device according to claim 8, the prism sheet is substantially equal to the effective emission region in the length direction from the reflection end surface portion to the incident end surface portion of the light guide plate. Light emitted from the region can be sufficiently condensed. For example, when the light guide plate has a wedge shape, the prism sheet can be accommodated in the effective emission region, so that it does not become thicker than the incident end surface portion of the light guide plate.

  In the flat illumination device according to the fifth aspect and the liquid crystal display device according to the ninth aspect, since the diffuser is substantially equal to the length from the incident end surface portion to the reflective end surface portion of the light guide plate, the incident end surface of the light guide plate and the light source Even at a place substantially equal to the height, it does not exceed the height of the light source, and the light shielding body can be prevented from sticking at places other than the effective emission region of the light guide plate.

In the flat illumination device according to claim 6 and the liquid crystal display device according to claim 10, the light shield has an opening in the effective emission region of the light guide plate and has a size equal to or greater than that of the light guide plate. When the length is equal to the length of the light guide plate, light leakage from the vicinity of the light source position can be blocked.
Moreover, when the light shielding body is longer than the length of the light guide plate, it is possible to block light leakage and outgoing light from places other than the effective light emission region of the light guide plate.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
The present invention includes a case in which a light source is provided at or near the incident end surface portion of the light guide plate, and a diffuser, a prism sheet, and a light shield are positioned above the light guide plate and housed therein. Among the diffusers and prism sheets provided on the effective emission region of the light guide plate, by extending the diffuser provided immediately above the light guide plate from the reflective end surface portion of the light guide plate toward the incident end surface portion, these light guide plates and The accumulated thickness of the diffuser and the prism sheet does not become thicker than the thickness of the light source, and even if a light shield is attached to the top of these, the light shield is still attached to the surface portion of the light guide plate outside the effective emission area of the light guide plate. Therefore, the present invention provides a flat illumination device capable of further improving luminance without generating a luminance deviation or luminance unevenness, and a liquid crystal display device using the flat illumination device.

  1 is a schematic perspective view of a liquid crystal display device according to the present invention, FIG. 2 is a schematic cross-sectional view of a flat illumination device according to the present invention, and FIGS. 3 (a) and 3 (b) are guides of the flat illumination device according to the present invention. FIG. 4 is a perspective front view of the flat illuminating device according to the present invention, and FIG. 5 is a schematic plan view showing a measurement position at the time of luminance measurement in the light guide plate of the flat illuminating device according to the present invention. .

  As shown in FIG. 1, the liquid crystal display device 1 has a configuration in which a liquid crystal display body 2 is disposed on an upper part of a flat illumination device 3. The liquid crystal display 2 can be composed of a transmissive liquid crystal represented by a TFT or the like. When the liquid crystal display 22 is a TFT or the like, a large number of pixels corresponding to RGB are provided, and light is transmitted through an RGB filter by a light shutter function corresponding to RGB signals to provide information such as color images and characters. is doing. Further, the liquid crystal display 2 may be a transflective liquid crystal, and uses a backlight when the outside light is dark such as at night or when the light is shining such as sunlight.

  The flat illumination device 3 includes a reflector 10 below the case 9, and is configured by arranging a light guide plate 4, a diffuser 6, a prism sheet 7, and a light shield 8 in this order toward the top of the case 9. The light source 5 is provided in the vicinity of the side portion of the light guide plate 4.

  The light guide plate 4 is formed by molding with a transparent acrylic resin (PMMA), polycarbonate (PC) or the like having a refractive index of about 1.4 to 1.7. As shown in FIGS. 3A and 3B, the light guide plate 4 emits light from an incident end face portion 4c that guides light from the light source 5, a reflective end face portion 4e that faces the incident end face portion 4c, and the light. A front surface portion 4a, a back surface portion 4b opposite to the front surface portion 4a, a side surface portion 4f in contact with the reflection end surface portion 4e, the front surface portion 4a and the back surface portion 4b, and a side surface portion 4f in the direction of the incident end surface portion 4c. It consists of an inclined side surface portion 4g connected to the end surface portion 4c.

  Furthermore, as shown in FIG. 2 and FIG. 3A, the light guide plate 4 is different in thickness between the incident end surface portion 4c and the reflective end surface portion 4e, and the incident end surface portion 4c is thicker than the reflective end surface portion 4e. It has become. The back surface portion 4b is a flat surface, but the surface portion 4a is gradually thickened from the flat surface forming the effective emission region L toward the incident end surface portion 4c, and the inclined surface following the incident end surface portion 4c. Part 4d is formed. Although not shown here, the incident end face portion 4c is provided with irregularities such as prisms and lenses in order to diffuse light.

  Here, the height (thickness) of the light source 5 is set to the maximum height, and even if the light guide plate 4 and the diffuser 6 and the prism sheet 7 provided above the light guide plate 4 are included, the height is equal to or higher than the light source 5. The flat illuminating device 3 is made thin, and can contribute to the thinning of the liquid crystal display device 1. However, the incident end face portion 4c of the light guide plate 4 is the same as the reflective end face portion 4e. A rectangular shape thinner than the height (thickness) of the light source 5 as a whole may be used. That is, the light guide plate 4 only needs to be formed so that the flat surface portion forming the effective emission region L is at least thinner than the height (thickness) of the light source 5.

In the light guide plate 4, the light incident from the incident end face portion 4 c travels into the light guide plate 4 in a range where the refraction angle γ satisfies 0 ≦ | γ | ≦ Sin ⁻¹ (1 / n). For example, since the refractive index of acrylic resin, which is a resin material used for the general light guide plate 4, is about n = 1.49, the light incident from the incident end face portion 4c falls within the range of the refraction angle γ = ± 42 °. is there.

  Further, the light incident on the light guide plate 4 within the range of the refraction angle γ = ± 42 ° is Sin α = (1 / n) at the boundary surface between the light guide plate 4 and the air layer (refractive index is n = 1). Can represent the critical angle. For example, since the refractive index of acrylic resin, which is a resin material used for the general light guide plate 4, is about n = 1.49, the critical angle α is about α = 42 °.

  Further, although not shown, the light guide plate 4 is provided with uneven processing such as an arc shape or a groove shape on the front surface portion 4a and the back surface portion 4b. Therefore, as described above, the light from the light source 5 is guided into the light guide plate 4 from the incident end surface portion 4c of the light guide plate 4, and the light existing in the light guide plate 4 is flat with the thickness of the light guide plate 4 being constant. If there is no unevenness such as an arc shape or a groove shape, light does not leak from the light guide plate 4 to the outside. And the light which exists in the light-guide plate 4 is reflected and refracted by uneven | corrugated | grooved parts, such as the above-mentioned circular arc shape or groove shape, and the light or circle by which some light was deflected by reflection angle by reflection. Light reaching an uneven portion such as an arc shape or a groove shape is refracted at the emission surface portion (surface portion 4 a), and light can be emitted from the surface portion 4 a (output surface portion) of the light guide plate 4.

  As shown in FIG. 1, the light guide plate 4 has a plurality of protrusions 4 h other than the direction toward the light source 5 for positioning purposes and fixing. These protrusions 4 h are inserted into holes 9 c provided on the outer peripheral inner wall surface of the case 9.

  The diffuser 6 is formed by applying transparent beads having different refractive indexes to the surface of a transparent sheet-like base material such as polyethylene terephthalate (PET), acrylic resin (PMMA), or polycarbonate (PC), and the like. The light that has entered through is refracted by the beads and diffuses in all directions.

  Further, the diffuser 6 has fine irregularities on the front and back surfaces of these base materials, and diffuses one light beam in a random direction when the light passes through the diffuser 6, so that the luminance of the light emitted from the light guide plate 4 is increased. The emitted light is made uniform so as not to notice the difference.

  Further, as shown in FIG. 2, the diffuser 6 has an incident end face portion 4c of the light guide plate 4 which is longer than the length of the effective emission region L of the flat illumination device 3 corresponding to the effective emission region where the liquid crystal display device 1 is observed. It is long in the direction. That is, the diffuser 6 only needs to be formed longer in the direction of the incident end surface portion 4c of the light guide plate 4 than the length of the effective emission region L, and the length from the incident end surface portion 4c of the light guide plate 4 to the reflection end surface portion 4e. It can also be formed approximately equal to. As a result, when the light shielding body 8 provided on the uppermost portion where the members necessary for the flat illumination device 3 such as the prism sheet 7 are overlapped, the light shielding body 8 is directly attached to the inclined surface portion 4d (surface portion 4a) of the light guide plate 4. ) So as not to stick to the portion, and no luminance deviation or luminance unevenness is generated, and the luminance can be further improved.

  As shown in FIG. 1, the diffuser 6 has a plurality of protrusions 6 b other than the direction toward the light source 5 for positioning purposes and fixing. These protrusions 6 b are inserted into holes 9 c provided on the outer peripheral inner wall surface of the case 9.

  The prism sheet 7 is configured by forming a shape such as a fine prism or lens array on the front and back surfaces of a transparent polyester resin base material with an acrylic resin layer. In addition, the prism sheet 7 may have a shape such as a fine prism or lens array formed on the front or back surface of a transparent acrylic resin or polycarbonate. In the prism sheet 7, the light incident from the light guide plate 4 through the diffuser 6 is condensed when passing through the prism sheet 7. Thereby, the emitted light from the prism sheet 7 can be brightened.

  Further, the prism sheet 7 is formed in a size substantially equal to the effective emission region L with respect to the length direction from the reflection end surface portion 4 e to the incident end surface portion 4 c of the light guide plate 4. In this example, the prism sheet 7 is cut (die cut) to the size of the effective emission area L of the flat illumination device 3 corresponding to the effective emission area where the liquid crystal display device 1 is observed. As shown in FIG. 1, the prism sheet 7 has a plurality of protrusions 7 b other than the direction toward the light source 5 for positioning purposes and fixing. These protrusions 7 b are inserted into holes 9 c provided on the outer peripheral inner wall surface of the case 9.

  Further, in the example of FIG. 1, two prism sheets 7 are used, and once condensed in the horizontal direction, the light is condensed again in the vertical direction to emit light with higher luminance.

  The light shielding body 8 is formed by printing or applying black ink or the like on the surface of a transparent sheet-like substrate such as polyethylene terephthalate (PET), acrylic resin (PMMA), or polycarbonate (PC). An acrylic adhesive is applied to the back surface. Moreover, the light shielding body 8 may not be transparent (for example, white), and can prevent the base material itself from firing and transmitting light. The light shielding body 8 has an opening 8 b in the effective emission region L, and is formed with a dimension at least equal to or larger than the surface portion 4 a of the light guide plate 4.

  Specifically, as shown by the hatched portion in FIG. 4, the light shield 8 of this example has a shape like a frame edge and has an opening 8 b that has nothing in the effective emission region L, and is connected to the light source 5. It is formed to be able to be accommodated in the case 9 with a size that covers the optical plate 4. As a result, portions other than the effective emission region L of the flat illumination device 3 corresponding to the effective emission region where the liquid crystal display device 1 is observed (diffuses other than the inside and part of the frame of the case 9, the light source 5, and the effective emission region L). The leakage light from the body 6 and the prism sheet 7) and the reflected light from the inside and part of the frame of the case 9, the light source 5, the diffuser 6 other than the effective emission region L, the prism sheet 7 and the like are not observed from the liquid crystal display device 1 side. Shield from light.

  In addition, the acrylic adhesive adhesive is apply | coated to the light-shielding body 8 of this example on both surface parts of the surface and a back surface, and the liquid crystal display body 2 is affixed and fixed by the adhesive adhesive of a surface.

  The light source 5 is configured by providing a conductive pattern on an injection or transfer mold type lead frame or an electrically insulating substrate, bonding a semiconductor light emitting element with a die bonder, and bonding to a conductive pattern with a bonding wire. be able to.

  When the light source 5 is an injection or transfer mold type, a lead frame made of a phosphor bronze material or the like in which a pattern is formed in a resin by insert molding is inserted to form a resin on the lead frame.

  The light source 5 is a high-luminance light-emitting element such as a quaternary compound or a compound such as InGaAlP, InGaAlN, or InGaN as a semiconductor light-emitting element.

  Further, in recent years, the liquid crystal display device 1 for color images has become mainstream, and white light is required as the emitted light from the flat illumination device 3, so that an RGB semiconductor light emitting element may be used. For the purpose of (thinning), it is preferable to employ pseudo white using a wavelength conversion material.

  Therefore, in a configuration using a wavelength conversion material, for example, a transparent adhesive mixed with a wavelength conversion material (YAG system) that is excited by blue emitted light from an InGaAlN semiconductor light emitting element and emits yellow or orange light is emitted from the semiconductor. It can be applied to the element and mixed with the blue light emission color of the semiconductor light emitting element itself and the light emission color such as yellow or orange from the wavelength conversion material to obtain a white light emission color.

  The light source 5 is provided in the vicinity so that the opening 5a faces the incident end surface portion 4c of the light guide plate 4 so as to contact the incident end surface portion 4c of the light guide plate 4, or the incident end surface portion 4c or side surface of the light guide plate 4 is disposed. The part 4f and the light source 5 are processed so that the light guide plate 4 and the light source 5 are fitted to each other.

  Case 9 is an insulating resin material such as modified polyamide, polyethylene terephthalate, nylon 46, aromatic polyester, or the like, and titanium oxide or the like for improving light reflectivity and light shielding properties. A white powder mixed with white powder is molded into a shape having an opening above by heat injection molding.

  Further, the case 9 may have a bottom portion, and has a shape of only a frame as in this example, and an opening hole 9b is formed in the portion that hits the bottom portion, and the reflector 10 is formed in the opening hole 9b. The leakage light from the light source 5 and the light guide plate 4 is returned again into the light guide plate 4 or reflected in the direction of the exit surface.

  Further, the case 9 has a plurality of positioning portions 9c made of slit-shaped grooves, holes, and the like on the outer peripheral inner wall surface. The positioning portions 9c are provided corresponding to the protrusions 4h of the light guide plate 4, the protrusions 6b of the diffuser 6, and the protrusions 7b of the prism sheet 7, respectively. And the protrusion part 4h of the light-guide plate 4, the protrusion part 6b of the diffuser 6, and the protrusion part 7b of the prism sheet 7 are each inserted in these positioning parts 9c. As a result, the light guide plate 4, the diffuser 6, and the prism sheet 7 are positioned and fixed to the case 9, and displacement can be prevented.

  The reflector 10 is made of a material that reflects completely, such as metal, and has a strength that can be used instead of the bottom of the case 9. In addition, the reflector 10 is applied to a position corresponding to the side surface portion 4 f of the flat illumination device 3, and is attached to and integrated with the bottom surface of the case 9.

  Thus, the thickness (height) of the light source 5 that is the maximum thickness (height) among the members incorporated in the flat illumination device 3 that emits light corresponding to the effective emission region actually observed of the liquid crystal display device 1 ( In accordance with (height), the accumulated total thickness (total height) of the diffuser 6 and the plurality of prism sheets 7 is set to be equal to or less than the thickness (height) of the light source 5. Therefore, only the incident end surface portion 4c of the light guide plate 4 is made equal to the thickness (height) of the light source 5, and the thicknesses of the other surface portion 4a and the back surface portion 4b are reduced, and the upper surface of the surface portion 4a. When the light diffuser 6 and the plurality of prism sheets 7 are accommodated in and the light shield 8 is pasted thereon, the light shield 8 adheres to the surface portion 4a of the light guide plate 4 to generate a luminance deviation or a luminance spot or luminance. The diffuser 6 is configured to extend to the vicinity of the incident end face portion 4c of the light guide plate 4 that does not exceed the thickness (height) of the light source 5 so as not to cause a decrease in the above. Thereby, even if the light shielding body 8 is attached, the light shielding body 8 is not attached to the surface portion 4a of the light guide plate 4. Therefore, luminance deviation and luminance unevenness do not occur, and the luminance can be further improved.

  Here, the results of luminance measurement of the flat illumination device of this example and the conventional flat illumination device are shown in Table 1 below. The measurement conditions were LED supply current: 15 mA / chip, aperture diameter: equivalent to 6.0φ, LED luminance: 1000 mcd, luminance meter: CCD surface spot measuring device. Further, as shown in FIG. 5, nine measurement points are selected from locations close to the light source, the distance between the centers of the measurement points parallel to the light source is 10.62 mm, and each measurement point in the depth direction of the light source is measured. The distance between the centers was 15.66 mm.

  As is clear from Table 1 above, the luminance deviation improved from 78.8% to 79.9%, and overall the luminance (minimum 2% to maximum 9%) could be increased.

  As described above, the liquid crystal display device and the flat illumination device according to the present invention include a light source, an incident end surface portion that guides light from the light source, a reflection end surface portion that is located opposite to the incident end surface portion, an exit surface that emits light, and an exit surface. A light guide plate comprising a back surface portion located opposite to the surface, a diffuser that diffuses light emitted from the light guide plate, a prism sheet that condenses light emitted from the diffuser, and the like, provided above the prism sheet A light-shielding body, and a light source, a light guide plate, a diffuser, a prism sheet, and a case for housing the light-shielding body. The diffuser provided on the upper side is elongated from the reflection end surface portion of the light guide plate toward the incident end surface portion. As a result, even if a light shielding body is attached to the uppermost part of the prism sheet or the like, the light shielding body does not adhere to the surface of the light guide plate outside the effective emission area of the light guide plate, and the accumulated thickness of the light guide plate, the diffuser, and the prism sheet Therefore, the brightness does not become thicker than the thickness of the light source, the brightness deviation and brightness spots do not occur, and the brightness can be further improved.

  Suitable for small mobile products such as liquid crystal display devices and flat lighting devices for backlights of this liquid crystal display device. Thin, light weight, high brightness, easy to see, and adequate for places with external light. A liquid crystal display device and a flat illumination device that can be provided can be provided.

1 is a schematic assembled perspective view of a liquid crystal display device according to the present invention. It is a schematic sectional drawing of the plane illuminating device which concerns on this invention. (A), (b) It is sectional drawing and front view of the light-guide plate of the planar illuminating device which concerns on this invention. It is a see-through | perspective front view of the plane illuminating device which concerns on this invention. It is a schematic plan view which shows the measurement point at the time of the brightness | luminance measurement shown in Table 1 in the light-guide plate of the planar illuminating device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Liquid crystal display body 3 Planar illuminating device 4 Light guide plate 4a Front surface part 4b Back surface part 4c Incident end surface part 4d Inclined surface part 4e Reflective end surface part 4f Side surface part 4g Inclined side surface part 4h Protrusion part 5 Light source 6 Diffuser 6b Protrusion Part 7 Prism sheet 7b Protruding part 8 Light shield 8b Opening 9 Case 9b Opening hole 9c Positioning part 10 Reflector L Effective emission area γ Refraction angle n Refractive index α Critical angle

Claims (10)

A light source;
A light guide plate comprising an incident end face for guiding light from the light source, a reflective end face located opposite to the incident end face, an exit face emitting the light, and a back face located opposite to the exit face When,
A diffuser for diffusing the light emitted from the light guide plate;
A prism sheet for condensing the light emitted from the diffuser,
A light shield provided above the prism sheet;
Including at least the light source, the light guide plate, the diffuser, the prism sheet, and the light shielding body.
In the light guide plate, at least a portion of a flat surface forming an effective emission region is thinner than the height of the light source,
The flat illuminating device characterized in that the diffuser is made longer from the reflective end face portion toward the incident end face portion than the effective emission region of the light guide plate above the light guide plate. A liquid crystal display,
A light source;
An incident end face that guides light from the light source, a reflective end face located opposite to the incident end face, an exit face that emits the light toward the liquid crystal display, and opposite the exit face A light guide plate composed of a back surface portion,
A diffuser for diffusing the light emitted from the light guide plate;
A prism sheet for condensing the light emitted from the diffuser,
A light shield provided above the prism sheet;
Including at least the light source, the light guide plate, the diffuser, the prism sheet, and the light shielding body.
In the light guide plate, at least a portion of a flat surface forming an effective emission region is thinner than the height of the light source,
The liquid crystal display device according to claim 1, wherein the diffuser is made longer from the reflection end face portion toward the incident end face portion than the effective emission region of the light guide plate above the light guide plate. The flat illumination device according to claim 1, wherein the light guide plate has the incident end surface portion substantially equal to a height of the light source. The flat illumination device according to claim 1, wherein the prism sheet is substantially equal to the effective emission region in a length direction of the incident end surface portion from the reflection end surface portion of the light guide plate. 2. The flat illumination device according to claim 1, wherein the diffuser is substantially equal to a length from the incident end surface portion to the reflective end surface portion of the light guide plate. The flat illumination device according to claim 1, wherein the light shield has an opening in an effective emission region of the light guide plate and has a size equal to or greater than that of the light guide plate. The liquid crystal display device according to claim 2, wherein the light guide plate has the incident end face portion substantially equal to a height of the light source. 3. The liquid crystal display device according to claim 2, wherein the prism sheet is substantially equal to the effective emission region in a length direction of the incident end surface portion from the reflection end surface portion of the light guide plate. The liquid crystal display device according to claim 2, wherein the diffuser is substantially equal to a length from the incident end surface portion to the reflective end surface portion of the light guide plate. The liquid crystal display device according to claim 2, wherein the light shielding body has an opening in an effective emission region of the light guide plate and has a size equal to or larger than the light guide plate.

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