Patent Description:
As a direct backlight to be mounted on a liquid crystal display apparatus, a backlight is known that uses a resin-made reflective plate that reflects light from a light source (for example, see PTL <NUM>). PTL <NUM> attempts to improve the contrast of emitted light with use of the reflective plate. Further conventional examples of liquid crystal display apparatuses and reflective plates thereof are described in PTL <NUM> or PTL <NUM>.

However, recently, a light-emitting device has been desired that achieves surface-emitted light having a more uniform luminance distribution while further enhancing the use efficiency of light from a light source despite a compact configuration.

It is therefore desirable to provide a light-emitting device that exhibits superior luminance contribution rate of a light source while reducing in-plane luminance unevenness despite a simple configuration, and a display apparatus and a lighting apparatus that include such a light-emitting device.

This desire is met by display apparatuses including light-emitting devices in accordance with the appended claims.

According to the light-emitting device of the embodiment of the invention, it is possible to achieve both improvement in uniformity of the in-plane luminance and improvement in luminance contribution rate of each of the light sources without disturbing weight reduction. In other words, the light-emitting device makes it possible to efficiently emit the light with reduced in-plane luminance unevenness. Therefore, according to the display apparatus with use of the light-emitting device, it is possible to exhibit superior image expression. Further, according to the lighting apparatus with use of the light-emitting device, it is possible to perform more uniform illumination onto an object. It is to be noted that the effects of the disclosure are not limited to the effects described above, and may be any of the effects described hereinbelow.

Hereinafter, some examples and embodiments of the invention are described in detail with reference to the drawings. It is to be noted that the description is given in the following order.

A light-emitting device in which a thickness of a sloped section of a reflective plate is greater than a thickness of a top surface section of the reflective plate.

A light-emitting device in which a high-reflective film is formed on a sloped section of a reflective plate.

A light-emitting device in which an uneven structure is provided on a sloped section of a reflective plate.

Examples where a sloped section of a reflective plate is configured by a curved surface.

Examples where an uneven structure is formed on a top surface section of a reflective plate.

An example where top end edges of adjacent sloped sections of a reflective plate are made to come close to each other.

An example where light from a light source is subjected to wavelength conversion using a wavelength conversion sheet.

<FIG> is a schematic cross-sectional view of an overall configuration of a light-emitting device <NUM> according to a first example of the useful for understanding, but not forming part of the invention. <FIG> is an enlarged cross-sectional view of a configuration of a key part of the light-emitting device <NUM> illustrated in <FIG>. Further, <FIG> is an enlarged plan view of a planar configuration of a reflective plate <NUM> in the light-emitting device <NUM>. It is to be noted that <FIG> corresponds to a cross-section in the direction of an arrow taken along a line I-I illustrated in <FIG>. The light-emitting device <NUM> is used, for example, as a backlight that illuminates a transmissive liquid crystal panel from behind, or as a lighting apparatus indoors or at any other place.

The light-emitting device <NUM> includes a substrate <NUM> on which a plurality of light sources <NUM> are provided on a top surface 2S1, and the reflective plate <NUM> that is placed on the substrate <NUM>. The light-emitting device <NUM> may further include, for example, an optical sheet <NUM>, a stud <NUM> (see <FIG>), a drive circuit <NUM>, or any other relevant component part. The drive circuit <NUM> serves to drive, for example, the light sources <NUM>, and is provided on a rear surface 2S2 of the substrate <NUM>, for example.

In this specification, a direction of a distance connecting the substrate <NUM> and the optical sheet <NUM> is designated as a Z-direction (a front-back direction), and a horizontal direction and a vertical direction on principal surfaces (the widest surfaces) of the substrate <NUM> and the optical sheet <NUM> are designated as an X-direction and a Y-direction, respectively.

The plurality of light sources <NUM> are arranged on the top surface 2S1 of the substrate <NUM> in matrix, for example. The light source <NUM> is a point light source, and is specifically configured by a light-emitting diode (LED) that oscillates white light. The plurality of light sources <NUM> are disposed one by one at a plurality of openings <NUM> that are formed on the reflective plate <NUM>, for example.

The reflective plate <NUM> has a function of performing optical actions such as reflection, diffusion, and scattering of incident light. The reflective plate <NUM> includes a bottom surface section <NUM> where the openings <NUM> into which the respective light sources <NUM> are inserted are formed therein; a sloped section <NUM> that includes a surface <NUM> that is sloped relative to the substrate <NUM> while surrounding the openings <NUM>, and has a thickness T1; and a top surface section <NUM> that is coupled to a top end of the sloped section <NUM>, and has a thickness T2. Here, the thickness T1 of the sloped section <NUM> is greater than the thickness T2 of the top surface section <NUM> (<FIG>). The bottom surface section <NUM> is in contact with the top surface 2S1 of the substrate <NUM>, is coupled to a bottom end of the sloped section <NUM>, and has a thickness T3. The top surface section <NUM> is distant from the substrate <NUM>, and extends along the top surface 2S1, for example. The light source <NUM> includes a light-emitting point LP at a top end on an optical axis CL. The thickness T3 of the bottom surface section <NUM> is smaller than a distance L3 from the substrate <NUM> to the light-emitting point LP, in order not to block light travelling toward the sloped section <NUM> after being emitted from the light source <NUM>. It is to be noted that the thickness T1 is a dimension of the sloped section <NUM> in a direction orthogonal to the surface <NUM>; the thickness T2 is a dimension of the top surface section <NUM> in a direction orthogonal to a top surface <NUM> (a surface, of the top surface section <NUM>, facing the optical sheet <NUM>); and the thickness T3 is a dimension of the bottom surface section <NUM> in a direction orthogonal to the top surface 2S1.

As illustrated in <FIG>, in an X-Y plane, the opening <NUM>, a borderline K1 between the bottom surface section <NUM> and the sloped section <NUM>, and a borderline K2 between the sloped section <NUM> and the top surface section <NUM> each have a circular shape, for example. That is, the sloped section <NUM> has a shape of expanding in a mortar form from the substrate <NUM> toward the optical sheet <NUM>. However, a planar shape of each of the opening <NUM>, the borderline K1 between the bottom surface section <NUM> and the sloped section <NUM>, and the borderline K2 between the sloped section <NUM> and the top surface section <NUM> is not limited to the circular shape, and may take any other shapes such as an ellipse and a polygon. It is to be noted that, in the X-Y plane, center points of the opening <NUM> and the sloped section <NUM> surrounding the opening <NUM> may preferably coincide with the optical axis CL of the light source <NUM>.

For the reflective plate <NUM>, the bottom surface section <NUM>, the sloped section <NUM>, and the top surface section <NUM> may be preferably molded integrally through, for example, cutting-out machining of a plate-like member, or a molding process such as injection molding and thermal press molding. Examples of a constituent material for the reflective plate <NUM> include acrylic resin such as polycarbonate resin and polymethylmethacrylate resin (PMMA), polyester resin such as polyethylene terephthalate, amorphous copolymerized polyester resin such as a copolymer of methylmethacrylate and styrene (MS), polystyrene resin, and polyvinyl chloride resin.

Because the light-emitting device <NUM> is provided with the reflective plate <NUM>, light emitted from the light source <NUM> is reflected on the surface <NUM> of the sloped section <NUM> to proceed toward the optical sheet <NUM>, or the light that returns from the optical sheet <NUM> after being emitted from the light source <NUM> to reach the optical sheet <NUM> is reflected, diffused, or scattered on the sloped section <NUM>, the top surface section <NUM>, or the bottom surface section <NUM> to proceed toward the optical sheet <NUM>. Such an action allows the light-emitting device <NUM> with the reflective plate <NUM> mounted thereon to focus light on a region desired to be illuminated while enhancing front luminance with efficient use of light from the light source <NUM>, thus making it possible to achieve improvement of area contrast performance. Further, flattening of the luminance distribution in the X-Y plane is achieved to ensure that a boundary with respect to light from the other adjacent light source <NUM> does not appear obviously. In particular, in the present example, the sloped section <NUM> that directly reflects the light emitted from the light source <NUM> has the thickness T1 that is greater than the thickness T2 of the top surface section <NUM> and the thickness T3 of the bottom surface section <NUM>. Therefore, even in a case where the reflective plate <NUM> is configured using the above-described thermoplastic resin that is superior in workability and is relatively lightweight, a light component, of the light having entered the surface <NUM> of the sloped section <NUM>, transmitting the sloped section <NUM> is reduced, thus leading to further improvement of the light use efficiency.

For example, as illustrated in <FIG>, the optical sheet <NUM> is placed on top of heads of a plurality of studs <NUM> that are erected on the top surface <NUM> of the top surface section <NUM> of the reflective plate <NUM>. The optical sheet <NUM> is disposed to face the light source <NUM> and the reflective plate <NUM> in a manner of covering the plurality of light sources <NUM> in common. The top surface <NUM> and a rear surface <NUM> of the optical sheet <NUM> are held at a fixed distance L1 by the plurality of studs <NUM> (see <FIG>). The optical sheet <NUM> is configured to laminate, for example, a plurality of sheet-like members such as a diffusion plate, a diffusion sheet, a lens film, and a polarization split sheet. <FIG> illustrates such a plurality of sheet-like members as a single laminated structure as a whole. Providing such an optical sheet <NUM> allows the light emitted from the light source <NUM> in an oblique direction or the light outgoing from the reflective plate <NUM> in an oblique direction to rise in a front direction, which makes it possible to further enhance the front luminance.

It is to be noted that, in the light-emitting device <NUM>, a width W1 between top ends of the sloped section <NUM> ranges, for example, from about <NUM> to about <NUM>; a width W2 between bottom ends of the sloped section <NUM> ranges, for example, from about <NUM> to about <NUM>; a distance L2 from the surface 2S1 of the substrate <NUM> to the top surface <NUM> of the top surface section <NUM> ranges, for example, from about <NUM> to about <NUM>; and a distance OD from the surface 2S1 of the substrate <NUM> to the rear surface <NUM> of the optical sheet <NUM> ranges, for example, from about <NUM> to about <NUM>.

Because the light source <NUM> is a point light source, the light emitted from the light source <NUM> spreads in all <NUM>-degree directions from the light-emitting point LP of the light source <NUM>, and finally passes through the optical sheet <NUM> to be observed as emission light on outer side of the optical sheet <NUM> (on side opposite to the light source <NUM>). Here, in the light-emitting device <NUM> of the present example, the reflective plate <NUM> includes the sloped section <NUM> and the top surface section <NUM>. Consequently, the light emitted from the light source <NUM> is oriented by the sloped section <NUM> toward a direction directly above the light source <NUM>, and is scattered moderately by the top surface section <NUM>. Further, in the reflective plate <NUM>, the thickness T1 of the sloped section <NUM> is set to be greater than the thickness T2 of the top surface section <NUM>. This reduces a light component, of the light emitted from the light source <NUM>, transmitting the sloped section <NUM>, thus leading to improvement of the reflection efficiency on the sloped section <NUM>. Meanwhile, for the top surface section <NUM> on which the light emitted from the light source <NUM> is not directly incident, even when the thickness T2 thereof is made smaller than the thickness T1 of the sloped section <NUM>, it is possible to suppress transmittance of incident light in the top surface section <NUM>. In such a manner, in the light-emitting device <NUM>, the thickness in the reflective plate <NUM> is varied depending on parts, thus making it possible to achieve weight reduction of the reflective plate <NUM> without sacrificing the reflection efficiency.

According to such a light-emitting device <NUM>, it is possible to achieve both improvement in the uniformity of the in-plane luminance and improvement in luminance contribution rate of each of the light sources <NUM> without disturbing whole weight reduction. In other words, it is possible to efficiently emit the light with reduced in-plane luminance unevenness despite a simple configuration. Thus, the use of the light-emitting device <NUM> in a display apparatus makes it possible to achieve enhanced contrast and enhanced luminance, thus allowing superior image expression to be exhibited. Further, the use of the light-emitting device <NUM> in a lighting apparatus makes it possible to perform more uniform illumination onto an object.

In the present example, for example, as in a reflective plate 3A as a first modification example illustrated in <FIG>, a high-reflective film <NUM> that covers the surface <NUM> of the sloped section <NUM> may be provided. The high-reflective film <NUM> is made of, for example, a material exhibiting higher reflectance than that of a constituent material for the reflective plate <NUM>, such as aluminum (Al) and silver (Ag), and is formed by means of, for example, a vapor-deposition technique and a non-electrolytic plating technique. According to the light-emitting device <NUM> with use of the reflective plate 3A, it is expected to further improve the luminance contribution rate of each of the light sources <NUM>.

Further, in the present example, for example, as in a reflective plate 3B as a second modification example illustrated in <FIG>, for example, a stepwise uneven structure <NUM> may be provided on the surface <NUM> of the sloped section <NUM>. According to the light-emitting device <NUM> with use of the reflective plate 3B, it is possible to moderately scatter the light from the light source <NUM> on the uneven structure <NUM> of the surface <NUM>, and thus it is expected to further improve the uniformity of the in-plane luminance.

In addition, in the present example, for example, as in a reflective plate 3C as a third modification example illustrated in <FIG>, a surface of the sloped section <NUM> may be configured by a curved surface <NUM>. In such a manner that the sloped section <NUM> has the curved surface <NUM>, it is possible to orient the light emitted from the light source <NUM> toward a direction directly above the light source <NUM>, for example. Therefore, according to the light-emitting device <NUM> with use of the reflective plate 3C, it is expected to further improve the luminance contribution rate of each of the light sources <NUM>. It is to be noted that the curved surface <NUM> is not limited to a concave surface such as a simple spherical surface illustrated in <FIG>, and may be alternatively a curved surface 36A formed of an aspherical surface as in a reflective plate 3D as a fourth modification example illustrated in <FIG>, for example. Further, as in these reflective plates 3C and 3D, even in a case where the sloped section <NUM> has the curved surfaces <NUM> and 36A, the maximum thickness T1 in the sloped section <NUM> may be preferably made greater than the thickness T2 of the top surface section <NUM>.

Further, in the present example, for example, as in reflective plates 3E and 3F as a fifth modification example and a sixth modification example respectively illustrated in <FIG> and <FIG> and <FIG> and <FIG>, uneven structures 37A and 37B may be provided on the top surface <NUM> of the top surface section <NUM>. That is, the top surface <NUM> of the top surface section <NUM> may preferably have smaller glossiness than that of the surface <NUM> of the sloped section <NUM>. It is to be noted that the glossiness is to be measured using a gloss meter (see "Japan Industrial Standards JISZ <NUM>: Specular Glossiness - Methods of Measurement"). The uneven structure 37A illustrated in each of <FIG> and <FIG> is configured in such a manner that a plurality of hemispherical protrusions 28A are disposed on the top surface <NUM>. The uneven structure 37B illustrated in each of <FIG> and <FIG> is configured in such a manner that a plurality of quadrangular-pyramid-like protrusions 28B are disposed on the top surface <NUM>. It is to be noted that <FIG> and <FIG> illustrate respectively cross-sections of the reflective plates 3E and 3F, and <FIG> and <FIG> illustrate planar surfaces of the reflective plates 3E and 3F that are taken along a line VIIIA-VIIIA and a line VIIIB-VIIIB illustrated in <FIG> and <FIG>, respectively.

In such reflective plates 3E and 3F, light that returns from the optical sheet <NUM> after being emitted from the light source <NUM> to reach the optical sheet <NUM> is scattered moderately on the uneven structures 37A and 37B of the top surface <NUM> to proceed toward the optical sheet <NUM>. With such an action, according to the light-emitting device <NUM> with use of these reflective plates 3E and 3F, the front luminance is enhanced with efficient use of the light from the light source <NUM>, and flattening of the luminance distribution in the X-Y plane is achieved. It is to be noted that the uneven structure of the top surface <NUM> is not limited to any of the uneven structures respectively illustrated in <FIG> and <FIG> and <FIG> and <FIG>. For example, the uneven structure may be configured by disposing a plurality of conical protrusions 28C on the top surface <NUM>.

Further, in the present example, for example, as in a reflective plate <NUM> as a seventh modification example illustrated in <FIG>, the borderlines K2 that are top end edges of the adjacent sloped sections <NUM> may come close to each other. Such a reflective plate <NUM> is suitable for a case where the plurality of light sources <NUM> are disposed on the substrate <NUM> in higher density.

<FIG> is a schematic cross-sectional view of an overall configuration of a light-emitting device <NUM> according to an embodiment of the invention. In the foregoing first example, the description has been given on the example where the white LED is used as the light source <NUM>. In the present embodiment, however, description is given on an example where an LED (for example, a blue LED) that emits light other than the white light is used as the light source.

The light-emitting device <NUM> further includes a wavelength conversion sheet <NUM> and may further include a wavelength selection sheet <NUM>. The wavelength conversion sheet <NUM> and the wavelength selection sheet <NUM> are provided inside the optical sheet <NUM>, for example. Specifically, for example, the optical sheet <NUM> has a structure in which a diffusion plate <NUM>, a lens film <NUM>, a polarization split sheet <NUM>, and a protective sheet <NUM> are laminated in order from side closer to the substrate <NUM>, and the wavelength conversion sheet <NUM> and the wavelength selection sheet <NUM> are inserted between the diffusion plate <NUM> and the lens film <NUM>, for example.

The wavelength conversion sheet <NUM> improves color-producing properties, for example, by performing wavelength conversion of incident light from the light source <NUM> to emit the converted light. The wavelength conversion sheet <NUM> includes a phosphor (a fluorescent material) such as fluorescent pigment and fluorescent dye, or a luminant having a wavelength conversion action such as a quantum dot. The wavelength conversion sheet <NUM> may be made in such a manner that resin containing the above-described fluorescent material or luminant is processed in a sheet-like form, or is printed at a predetermined region on another transparent substrate. Alternatively, the wavelength conversion sheet <NUM> may be made in such a manner that a layer of the fluorescent material or luminant is sealed between two transparent films.

The wavelength conversion sheet <NUM> is excited by light at a first wavelength (hereinafter referred to as first-wavelength light) that is emitted from the light source <NUM> through a rear surface <NUM>, and performs the wavelength conversion under the principle of fluorescence emission, for example, to emit, from a top surface <NUM>, light at a second wavelength (hereinafter referred to as second-wavelength light) that is different from the first wavelength. Here, the first wavelength and the second wavelength are not particularly limited. However, for example, in the case of a display application, it is preferable that the first wavelength be blue light (for example, a wavelength ranging from about <NUM> to about <NUM>), and the second wavelength be red light (for example, a wavelength ranging from about <NUM> to about <NUM>) or green light (for example, a wavelength ranging from about <NUM> to about <NUM>). In other words, a light source 1B is a blue light source; in such a case, the wavelength conversion sheet <NUM> performs the wavelength conversion of the blue light into the red light or the green light.

The wavelength conversion sheet <NUM> desirably includes a quantum dot. The quantum dot is a particle with a long diameter ranging from about <NUM> to about <NUM>, and has a discrete energy level. An energy state of the quantum dot depends on a size thereof, and therefore a change in the size allows for free selection of an emission wavelength. Further, emission light of the quantum dot has a narrow spectrum width. A color gamut is expanded by combining light having such a steep peak. Therefore, the use of the quantum dot as a wavelength conversion material allows the color gamut to be expanded with ease. Moreover, the quantum dot has high responsiveness, thus allowing for efficient use of the light from the light source <NUM>. In addition, the quantum dot exhibits high stability. The quantum dot is, for example, a compound of a group <NUM> element and a group <NUM> element, a compound of a group <NUM> element and a group <NUM> element, or a compound of a group <NUM> element and a group <NUM> element, and examples of the quantum dot include CdSe, CdTe, ZnS, CdS, PdS, PbSe, and CdHgTe.

The wavelength selection sheet <NUM> is an optical member having a function of mainly transmitting the first-wavelength light (for example, the blue light) and shielding the second-wavelength light (the green light and the red light).

In the light-emitting device <NUM>, in a case where an LED that emits the blue light is used as the light source <NUM>, a blue reflective sheet may be further provided on the reflective plate <NUM>. Alternatively, blue coating may be applied onto the surface <NUM> and the top surface <NUM> of the reflective plate <NUM>.

In the light-emitting device <NUM>, the light emitted from the light source <NUM> spreads in all <NUM>-degree directions from the light-emitting point LP of the light source <NUM>, and is finally observed as emission light on outer side of the optical sheet <NUM> (on side opposite to the light source <NUM>). Here, the light-emitting device <NUM> of the present embodiment is provided with the wavelength conversion sheet <NUM> and the wavelength selection sheet <NUM>, and therefore the light emitted from the light source <NUM> exhibits a behavior given below. That is, the light (described as blue light LB here) that is emitted from the light source <NUM> enters the diffusion plate <NUM> of the optical sheet <NUM> directly, or enters the diffusion plate <NUM> of the optical sheet <NUM> after being reflected or scattered on the reflective plate <NUM>. The blue light LB having passed through the diffusion plate <NUM> passes through the wavelength selection sheet <NUM>, and thereafter enters the wavelength conversion sheet <NUM>. The blue light LB having entered the wavelength conversion sheet <NUM> from the rear surface <NUM> is converted into red light LR (or green light LG) to be outputted from the top surface <NUM>. However, in some cases, the output light may also include the blue light LB that is not converted into the red light LR (or the green light LG). The output light from the top surface <NUM> passes through the lens film <NUM>, the polarization split sheet <NUM>, and the protective sheet <NUM> sequentially. However, return light is present that returns to the wavelength selection sheet <NUM> without being outputted from the top surface <NUM>. The blue light LLB of the return light enters the wavelength selection sheet <NUM> once again, and is subjected to the action such as reflection and scattering by the reflective plate <NUM> to be recycled. Meanwhile, the red light LLR (or the green light LLG) of the return light is reflected by the wavelength selection sheet <NUM> to pass through the wavelength conversion sheet <NUM>, the lens film <NUM>, the polarization split sheet <NUM>, and the protective sheet <NUM> sequentially. In such a manner, the light-emitting device <NUM> allows only the blue light LLB to be recycled, which significantly improves the surrounding coloring at the time of driving of partial lighting without causing degradation in the luminance.

<FIG> illustrates an external appearance of a display apparatus <NUM> according to a third embodiment of the technology. The display apparatus <NUM> includes the light-emitting device <NUM>, is used as, for example, a flat-screen television, and has a configuration in which a tabular main body section <NUM> for image display is supported by a stand <NUM>. It is to be noted that the display apparatus <NUM> is used as a stationary type that is placed on a horizontal plane such as a floor, a shelf, and a rack, with the stand <NUM> attached to the main body section <NUM>. However, the display apparatus <NUM> is also usable as a wall-hanging type, with the stand <NUM> detached from the main body section <NUM>.

<FIG> represents an exploded view of the main body section <NUM> illustrated in <FIG>. The main body section <NUM> includes, for example, a front exterior member (bezel) <NUM>, a panel module <NUM>, and a rear exterior member (rear cover) <NUM> in this order from front side (viewer side). The front exterior member <NUM> is a frame-shaped member that covers a front peripheral part of the panel module <NUM>, and a pair of speakers <NUM> is disposed on lower side thereof. The panel module <NUM> is fixed to the front exterior member <NUM>. A power supply substrate <NUM> and a signal substrate <NUM> are mounted on a rear surface of the panel module <NUM>, and a mounting fixture <NUM> is fixed to the rear surface of the panel module <NUM>. The mounting fixture <NUM> serves to mount a wall-mounting bracket, components such as a substrate, and the stand <NUM>. The rear exterior member <NUM> covers the rear surface and side surfaces of the panel module <NUM>.

<FIG> is an exploded view of the panel module <NUM> illustrated in <FIG>. The panel module <NUM> includes, for example, a front housing (a top chassis) <NUM>, a liquid crystal panel <NUM>, a frame-shaped member (a middle chassis) <NUM>, an optical sheet <NUM>, a reflective plate <NUM>, a substrate <NUM>, a rear housing (a back chassis) <NUM>, and a timing controller substrate <NUM> in this order from the front side (viewer side).

The front housing <NUM> is a frame-shaped metallic component that covers a front peripheral part of the liquid crystal panel <NUM>. The liquid crystal panel <NUM> includes, for example, a liquid crystal cell 122A, a source substrate 122B, and a flexible substrate 122C such as a chip on film (COF) that couples these component parts. The frame-shaped member <NUM> is a frame-shaped resin-made component that holds the liquid crystal panel <NUM> and the optical sheet <NUM>. The rear housing <NUM> is a metallic component made of iron (Fe) or any other meal material that accommodates the liquid crystal panel <NUM>, the frame-shaped member <NUM>, and the light-emitting device <NUM>. The timing controller substrate <NUM> is also mounted on a rear surface of the rear housing <NUM>.

In the display apparatus <NUM>, image display is performed by causing the liquid crystal panel <NUM> to selectively transmitting the light from the light-emitting device <NUM>. Here, the display apparatus <NUM> includes the light-emitting device <NUM> that achieves improvement in uniformity of the in-plane luminance distribution as described in the first example, thus leading to improvement in the display quality of the display apparatus <NUM>.

It is to be noted that, in the above-described embodiment, the description has been given on a case where the display apparatus <NUM> includes the light-emitting device <NUM> according to the first example. However, the display apparatus <NUM> may include the light-emitting device <NUM> according to the second embodiment as an alternative to the light-emitting device <NUM>.

Hereinafter, description is given on examples of application of the display apparatus <NUM> as described above to electronic apparatuses. Examples of the electronic apparatuses include a television, a digital camera, a notebook personal computer, a mobile terminal apparatus such as a mobile phone, and a video camera. In other words, the above-described display apparatus is applicable to electronic apparatuses in every field that display externally inputted image signals or internally generated image signals as images or video pictures.

<FIG> illustrates an external appearance of a tablet terminal apparatus to which the display apparatus <NUM> of the foregoing embodiment is applicable. <FIG> illustrates an external appearance of another tablet terminal apparatus to which the display apparatus <NUM> of the foregoing embodiment is applicable. Each of these tablet terminal apparatuses includes, for example, a display section <NUM> and a non-display section <NUM>, and the display section <NUM> is configured by the display apparatus <NUM> of the foregoing embodiment.

Each of <FIG> illustrates an external appearance of a tabletop lighting apparatus to which any of the light-emitting devices <NUM> and <NUM> of the foregoing embodiments is applicable. Each of these lighting apparatuses includes, for example, an illuminating section <NUM> attached to a support post <NUM> that is provided on a base <NUM>. The illuminating section <NUM> is configured by any of the light-emitting devices <NUM> and <NUM> according, respectively, to the foregoing first example and second embodiments. It is possible for the illuminating section <NUM> to take any shape such as a tubular shape illustrated in <FIG> and a curved surface shape illustrated in <FIG>, by configuring components such as the substrate <NUM>, the reflective plate <NUM>, and the optical sheet <NUM> in curved shapes.

<FIG> illustrates an external appearance of an indoor lighting apparatus to which any of the light-emitting devices <NUM> and <NUM> of the foregoing embodiments is applicable. The lighting apparatus includes an illuminating section <NUM> that is configured by any of the light-emitting devices <NUM> and <NUM> according to the foregoing embodiments, for example. The appropriate number of the illuminating sections <NUM> are disposed at appropriate spacing intervals on a ceiling 850A of a building. It is to be noted that the illuminating section <NUM> may be installed not only on the ceiling 850A, but also on a wall 850B or a floor (not illustrated in the diagram) depending on the intended use.

In these lighting apparatuses, illumination is performed through the light from the light-emitting devices <NUM> and <NUM>. Here, the lighting apparatuses include any of the light-emitting devices <NUM> and <NUM> that improve the uniformity of the in-plane luminance distribution, thus leading to improvement of illumination quality.

In the light-emitting device <NUM> according to the foregoing first example, luminance of light from the single light source <NUM> to be measured that was observed directly above the light source <NUM> was determined by simulation. Here, a comparison was made between a case where the thickness T1 of the sloped section <NUM> was set to <NUM> (Experimental Example <NUM>-<NUM>) and a case where the thickness T1 of the sloped section <NUM> was set to <NUM> (Experimental Example <NUM>-<NUM>). The thickness T2 of the top surface section <NUM> was set to <NUM> in both of these examples. The result is illustrated in <FIG>. In <FIG>, a horizontal axis denotes positions in the X-Y plane (<FIG>), and a vertical axis denotes the luminance. As seen from <FIG>, luminance determined in Experimental Example <NUM>-<NUM> (a curve line 17L1) was higher than luminance determined in Experimental Example <NUM>-<NUM> (a curve line 17L2). That is, it was confirmed that the luminance achieved from the light-emitting device <NUM> was enhanced by increasing the thickness of the sloped section.

Next, in the light-emitting device <NUM> with use of the reflective plate <NUM> illustrated in <FIG>, in a case where the single light source <NUM> to be measured, and other thirty-six light sources <NUM> equivalent to three rounds around the single light source <NUM> (six in a first round, twelve in a second round, and eighteen in a third round) were turned on, the luminance contribution rate and overall average luminance of the light source <NUM> to be measured that were observed directly above the light source <NUM> were determined by simulation. Further, the in-plane luminance distribution at the time when all of the above-described light sources <NUM> were turned on was determined by simulation.

In the light-emitting device <NUM> with use of the reflective plate 3C illustrated in <FIG>, a simulation similar to that of Experimental Example <NUM>-<NUM> was performed. Here, dimensions were specified such that the width W1 was <NUM>, the width W2 was <NUM>, the distance L2 was <NUM>, and a depth T4 of a slant surface <NUM> was <NUM> (a curvature R of the slant surface <NUM> was <NUM>).

With the exception that the depth T4 of the slant surface <NUM> was set to <NUM>, any other conditions were similar to those of Experimental Example <NUM>-<NUM>. Under such conditions, the luminance contribution rate and overall average luminance of the light source <NUM> to be measured were determined by simulation. Further, the in-plane luminance distribution at the time when all of the light sources <NUM> were turned on was determined by simulation.

The simulation result of each Experimental Example is summarized in <FIG>. As illustrated in <FIG>, as compared with Experimental Example <NUM>-<NUM> with use of the reflective plate <NUM> having the flat surface <NUM>, directly-overhead luminance contribution rate was improved in Experimental Examples <NUM>-<NUM> and <NUM>-<NUM> with use of the reflective plate 3C having the slant surface <NUM> that is formed as a curved surface. In other words, the light-collecting effect was obtained by causing curvature in the slant surface of the sloped section, thus leading to improvement of the directly-overhead luminance contribution rate. Therefore, it was found that causing curvature in the slant surface of the sloped section was expected to be utilized as a technique of improving the contrast performance. Further, in Experimental Example <NUM>-<NUM>, it was found that variations in the in-plane luminance were reduced as compared with Experimental Examples <NUM>-<NUM> and <NUM>-<NUM>. It is to be noted that the in-plane luminance distribution in <FIG> indicates that a part occupied by a deep color has higher luminance than that of a part occupied by a light color. Further, the directly-overhead luminance contribution rate as is defined here refers to a rate of the luminance at the time when one light source or a block of light sources is turned on in a case where the luminance at the time when all light sources are turned on is specified as <NUM>%. The numerical values of the directly-overhead luminance contribution rate and the average luminance in <FIG> are standardized under the condition that the result of Experimental Example <NUM>-<NUM> is defined as <NUM>.

A sample of the light-emitting device <NUM> that includes a reflective plate corresponding to the reflective plate 3E of the fifth modification example of the first example was produced, and the luminance distribution thereof was evaluated. Here, the in-plane luminance distribution was observed in a case where any single light source <NUM>, and other thirty-six light sources <NUM> equivalent to three rounds around the single light source <NUM> (six in a first round, twelve in a second round, and eighteen in a third round) were turned on. The top surface of a top surface section of the reflective plate was subjected to a cutting process to achieve scattering close to complete scattering. As a result, according to the present Experimental Example, it was confirmed that so-called particulate variability was reduced, and a difference in the luminance between a region directly above a light source and a clearance region of light sources was decreased, as compared with the case of a reflective plate with the flat top surface of the top surface section. Further, in the present experimental example, it was confirmed that the distance OD was reducible by about <NUM>%, which was suitable for reduction in a thickness of a light source device, in comparison with a typical structure with no use of a reflective plate.

A sample of the light-emitting device <NUM> according to the foregoing second embodiment was produced (Experimental Example <NUM>-<NUM>). Further, a sample of a light-emitting device that removed the wavelength selection sheet <NUM> from the configuration of the light-emitting device <NUM> was produced (Experimental Example <NUM>-<NUM>).

For each of the samples in these Experimental Examples <NUM>-<NUM> and <NUM>-<NUM>, the in-plane luminance distribution was measured. The results are illustrated in <FIG>. In <FIG>, a horizontal axis denotes a distance [mm] from a light emission center of the light source1, and a vertical axis denotes a luminance level (a relative value). Further, in <FIG>, a curved line 19L1 indicates a luminance distribution of Experimental Example <NUM>-<NUM>, and a curved line 19L2 indicates a luminance distribution of Experimental Example <NUM>-<NUM>. As illustrated in <FIG>, in a case where the wavelength selection sheet <NUM> was provided (Experimental Example <NUM>-<NUM>), a luminance increase of about <NUM>% was observed as compared with a case where the wavelength selection sheet <NUM> was not provided (Experimental Example <NUM>-<NUM>).

In addition, for each of the samples in these Experimental Examples <NUM>-<NUM> and <NUM>-<NUM>, the chromaticity distribution in an in-plane direction was measured at the time when turning on only the single light source <NUM> configured by an LED. The results are illustrated in <FIG>. In <FIG>, a horizontal axis denotes a distance [mm] from a light emission center of the light source1, and a vertical axis denotes chromaticity x. In <FIG>, a horizontal axis denotes a distance [mm] from a light emission center of the light source1, and a vertical axis denotes the chromaticity x. Further, in each of <FIG>, a curved line 20L1 indicates a chromaticity distribution of Experimental Example <NUM>-<NUM>, and a curved line 20L2 indicates a chromaticity distribution of Experimental Example <NUM>-<NUM>. As illustrated in <FIG>, in a case where the wavelength selection sheet <NUM> was provided (Experimental Example <NUM>-<NUM>), the steepness of chromaticity variation at the time of turning on the single light source <NUM> was reduced, thus leading to further improvement of the screen display quality, as compared with a case where the wavelength selection sheet <NUM> was not provided (Experimental Example <NUM>-<NUM>).

The disclosure has been described heretofore with reference to the embodiments, the modification examples, and the experimental examples thereof; however, the disclosure is not limited to the foregoing embodiments, modification examples, and experimental examples, and may be modified in a variety of ways. For example, a material and a thickness of each member described in the foregoing embodiments, modification examples, and experimental examples are not limited thereto, and any other material and thickness may be used, provided they fall within the scope of the claim. Further, the shape of a surface of the sloped section in the reflective plate, and the uneven structure of a top surface of the top surface section are not limited to those in the foregoing embodiments, modification examples, and experimental examples.

Further, for example, in the foregoing embodiments, the description has been given on the case where the light source <NUM> is an LED; however, the light source <NUM> may be configured by a device such as a semiconductor laser.

Additionally, for example, in the foregoing embodiments, modification examples, and experimental examples, the description has been given by citing, as a specific example, configurations of the light-emitting device <NUM> and the display apparatus <NUM> (the television); however, it is unnecessary to provide all of the components, or other components may be provided.

Claim 1:
A display apparatus (<NUM>) including a light-emitting device (<NUM>), the light-emitting device (<NUM>) comprising
a substrate (<NUM>) on which a light source (<NUM>) is provided, wherein
the light source (<NUM>) is configured to emit first-wavelength light other than white light, and
the light source (<NUM>) includes a light-emitting point (LP);
a wavelength conversion sheet (<NUM>) configured to perform wavelength conversion of the first-wavelength light into a second-wavelength light different from the first wavelength; and
a reflective member (<NUM>, 3A, 3B, 3C, 3D) comprising a resin, wherein the reflective member is placed on the substrate and includes
an opening (<NUM>) into which the light source (<NUM>) is inserted,
a sloped section (<NUM>) having a first thickness (T1), and the first thickness (T1) is a dimension of the sloped section (<NUM>) in a direction orthogonal to a sloped surface (<NUM>),
a bottom surface section (<NUM>) coupled to a bottom end of the sloped section (<NUM>),
wherein the bottom surface section (<NUM>) has a second thickness (T3),
the first thickness (T1) is greater than the second thickness (T3),
the light source (<NUM>) has a first distance (L3) from the substrate (<NUM>) to the light-emitting point (LP) of the light source, and
the second thickness (T3) is smaller than the first distance (L3).