Illuminating device and display apparatus

An illuminating device (200) according to the present invention is provided with: a substrate (4) having a surface, on which a plurality of light sources (3) are mounted; a housing (12), in which an opening is defined; a diffusion plate (9) that is disposed facing a bottom plate section (50) so as to close the opening; a duct (14) having an air inlet (23) and an air outlet (24); a fan (15) that generates an airflow in the duct (14); a first flow channel (P1); and a second flow channel (P2). The first flow channel (P1) communicates a space inside of the housing (12) closed by the diffusion plate (9) with the inside of the duct (14). The housing (12) is connected to, via a first opening (55) that is provided at the bottom plate section (50) or a side plate section (52), a venturi section (140) that is formed between the air inlet (23) and the air outlet (24) of the duct (14). Without being connected to the duct (14), the second flow channel (P2) communicates the inside and the outside of the housing (12) with each other via a second opening (56) that is provided at the bottom plate section (50) or the side plate section (52).

TECHNICAL FIELD

The present invention relates to an illuminating device, and a display apparatus equipped with the illuminating device.

BACKGROUND ART

There is a backlight as an example of an illuminating device. Such a backlight is used to illuminate a liquid-crystal panel in a liquid-crystal display as an example of a display apparatus. The backlight has light sources mounted on a substrate, and a housing that confines light emitted from the light sources. When the backlight is lit, the light sources of the backlight generate heat. Insufficient release of generated heat to the outside of the housing may cause the occurrence of a display defect of the liquid-crystal panel because liquid-crystal molecules filled in the liquid-crystal panel are denatured at high temperatures. In recent liquid-crystal display apparatuses, the luminance has particularly been increased. Increasing luminance arises a significant issue about heat dissipation because of an increase in the number of light sources used for the liquid-crystal display apparatuses, and in an amount of an input current into the light sources.

For example, Patent Literature 1 discloses a liquid-crystal display apparatus having the structure in which a substrate on which light sources as a heat source are mounted is attached to a metal bottom chassis as part of a housing.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

Increasing the number of light sources or an input current into the light sources to increase luminance of all the light sources causes, at the same time, an increase in a quantity of heat generated from all the light sources. In this case, in the heat dissipation structure of the liquid-crystal display apparatus of Patent Literature 1, a display defect may occur by a rise in temperature of the liquid-crystal panel or the like as a result of insufficient release, outside the housing, of heat from the substrate.

An object of the present invention is to provide an illuminating device capable of suppressing a rise in internal temperature of a housing, and a display apparatus including the illuminating device.

Solution to Problem

An illuminating device according to an aspect of the present invention includes a substrate, a housing, a diffusion plate, a duct, an air flow generator, a venturi section, a first flow channel, and a second flow channel. The substrate has a surface on which light sources are mounted. The housing has a bottom plate section that holds the substrate, and a side plate section that surrounds the bottom plate section. Here, an opening is defined by an end of the side plate section. The diffusion plate is disposed to face the bottom plate section and close the opening. The duct has an air inlet and an air outlet. The air flow generator generates an air flow inside the duct. The venturi section is formed between the air inlet and the air outlet of the duct such that an internal space of the housing closed with the diffusion plate communicates with an inside of the duct. The first flow channel is connected through a first opening provided at the bottom plate section or the side plate section. In the second flow channel, through a second opening provided at the bottom plate section or the side plate section, an outside of the housing is not connected to the duct but communicates with an inside of the housing.

A display apparatus according to an aspect of the present invention includes the illuminating device, a display panel, and an enclosure. The display panel has a display surface that displays an image. The display panel controls transmittance of light, incoming from an opposite surface of the display panel from the display surface through the diffusion plate, emitted from the light sources, thereby generating the image. The enclosure houses the display panel, the diffusion plate, the substrate, and the housing. The duct and the air flow generator are disposed between the bottom plate section and a facing section of the enclosure that faces the bottom plate section.

A display apparatus according to an aspect of the present invention includes the illuminating device, a display panel, and an enclosure. The display panel has a display surface that displays an image. The display panel controls transmittance of light, incoming from an opposite surface of the display panel from the display surface through the diffusion plate, emitted from the light sources, thereby generating the image. The enclosure houses the display panel, the diffusion plate, the substrate, and the housing. The air flow generator is disposed between the bottom plate section and a facing section of the enclosure that faces the bottom plate section. The duct is composed of fin-shaped projections formed on at least one of the bottom plate section, or the facing section.

Advantageous Effects of Invention

In the illuminating device and the display apparatus with the same according to an aspect of the present invention, the Venturi effect by the venturi section enables release, outside the housing, of the internal air of the housing warmed by the heat from the light sources, thereby suppressing a rise in internal temperature of the housing.

DESCRIPTION OF EMBODIMENTS

First Embodiment

FIG. 1is a cross-sectional view of a liquid-crystal display apparatus (display apparatus)100according to a first embodiment. The liquid-crystal display apparatus100includes a liquid-crystal panel (display panel)1that displays an image (including a moving image), a backlight (illuminating device)200that emits light toward the liquid-crystal panel1, and an enclosure that houses these components.

The backlight200includes light emitting diodes (LEDs)3as an example of light sources, a substrate4on which the LEDs3are mounted, and a back chassis5.

The LEDs3are disposed on a surface of the substrate4in rows and columns. The number of the LEDs mounted on the surface of the substrate4is set such that the number allows the desired luminance to be achieved. In the present embodiment, the pitch between the LEDs3is made sufficiently small in particular in order to realize the high-luminance liquid-crystal display apparatus100. Making the pitch between the LEDs3sufficiently small enables the realization of the high-luminance liquid-crystal display apparatus100and the suppression of non-uniform brightness in the liquid-crystal panel1.

The substrate4is preferably composed of metal with a high thermal conductivity such as aluminum from the viewpoint of heat dissipation. Here, in the present specification, the heat dissipation includes release of heat held by the liquid-crystal display apparatus100to the outside of the liquid-crystal display apparatus100. A rise in temperature of the liquid-crystal panel1is suppressed as a result of the heat dissipation. A copper foil patterns40is formed on the surface of the substrate4, and constitutes wiring for feeding an electric current to the LEDs3(seeFIG. 2). The wiring formed of the copper foil pattern40is electrically connected to an unillustrated driver circuit. The LEDs3convert electric power supplied from the driver circuit into light, thereby emitting light.

The back chassis5has a bottom plate section50, a side plate section52, an elongated section53, and a flange54. The bottom plate section50has a flat surface that is rectangular. The side plate section52is diagonally raised from peripheral edges of the bottom plate section50. The elongated section53is elongated from the side plate section52in parallel with the bottom plate section50. The flange54has a frame shape and is elongated from a peripheral edge of the side plate section52to spread parallel to the flat surface of the bottom plate section50.

Through holes51(seeFIG. 2) are formed at the bottom plate section50such that respective positions of the through holes51correspond to respective positions on the substrate4of optical axes of the LEDs3. Each of the through holes51is circular in shape in a plane perpendicular to a direction penetrating the bottom plate section50. The side plate section52is provided with a first opening55and second openings56which communicate the inside of the back chassis5with the outside of the back chassis5. For example, the first and second openings55and56have a slit shape and are extended over respective faces of the side plate section52. Alternatively, each of the first and second openings55and56may be, for example circular holes, or be formed at the bottom plate section50. Although the first opening55may be perpendicular to the side plate section52, it is preferable that the first opening55be inclined relative to the side plate section52so as to be along an air flow inside a duct14to be described later. The elongated section53is elongated from the side plate section52to the enclosure2, and separates an internal space of the enclosure2into an area forming the duct14and an area not forming the duct14. Note that the elongated section53may be formed separately from the back chassis5so as not to be part of the back chassis5.

In the present specification, the term “outward” means a direction away from the member in question, and the term “inward” means a direction opposite thereto (e.g., a direction of the center of gravity of the member). Unless stated otherwise, surfaces facing outward and inward in each of members constituting the display apparatus100are called external and internal surfaces, respectively. For example, a surface, facing outward relative to the back chassis5, of the bottom plate section50is called an external surface of the bottom plate section50, and a surface facing an opposite direction thereto (opposite surface) is called an internal surface of the bottom plate section50. Similarly, a surface, facing outward relative to the hack chassis5, of the side plate section52is called an external surface of the side plate section52, and an opposite surface thereto is called an internal surface. In the present embodiment, the substrate4is disposed outside the bottom plate section50of the back chassis5, The substrate4is screwed to and held by the bottom plate section50of the back chassis5.

Thermal insulation7that is sheet insulation is adhered to the external surface of the bottom plate section50of the back chassis5except respective places in which the through holes51are formed (seeFIG. 2). The thermal insulation7is disposed between the back chassis5and the substrate4, thereby suppressing thermal conduction from the substrate4to the back chassis5.

A reflection sheet13that reflects light is adhered to almost the entire internal surface of the bottom plate section50of the back chassis5except respective places in which the through holes51are formed (seeFIG. 2). The plate member6is stacked on the bottom plate section50from the inside of the back chassis5and closes the through holes51(seeFIG. 2). Specifically, the plate member6is placed on the internal surface of the bottom plate section50of the hack chassis5through the reflection sheet13. The plate member6is, for example one rectangular plate. Alternatively, plate members6may be disposed side by side on the bottom plate section50of the back chassis5. The plate member6is made of a resin material such as transparent acrylic, and has optical permeability. The plate member6may be fixed to the back chassis5by screwing. Note that the plate member6may not be necessarily provided.

FIG. 2is a cross-sectional view depicting a configuration of part of the display apparatus100according to the present embodiment. The LEDs3are disposed inside their respective corresponding through holes51. The entire surface of the substrate4is in contact with the external surface of the bottom plate section50of the back chassis5(through the thermal insulation7). The present configuration is therefore effective from the viewpoint of dust prevention because there is substantially no gap between the back chassis5and the substrate4.

As illustrated inFIG. 1, a panel chassis8has a rectangular frame shape whose outline substantially equals that of the back chassis5, and is in contact with the back chassis5with their respective outer edges aligned.

A diffusion plate9has front and back surfaces (first and second surfaces) that are rectangular, and side surfaces surrounding the front and back surfaces. The diffusion plate9is disposed parallel to the bottom plate section50. Each entire side surface of the diffusion plate9is fitted in a corresponding groove formed at an inner periphery of the panel chassis8, and thereby the diffusion plate9is held by the panel chassis8. The diffusion plate9is made of, for example a transparent resin material such as acrylic containing a light diffusion material. Specifically, the “containing a light diffusion material” means manufacture by using material in which particles that can scatter light are dispersed.

The diffusion plate9diffuses, in the inside of the diffusion plate9, light struck on a back surface (surface close to the bottom plate section50of the back chassis5) of the diffusion plate9, and emits it from the front surface (surface close to the liquid-crystal panel1).

In the present specification, from the viewpoint of directions, term “front” means a direction from the liquid-crystal display apparatus100toward a user, namely an image display direction of the liquid-crystal display apparatus100, and “back” means an opposite direction thereto. Unless stated otherwise, a surface directed forward and a surface directed backward in members constituting the display apparatus100are called a first surface and a second surface, respectively. That is, the diffusion plate9diffuses, in the inside of the diffusion plate9, light struck on the second surface, and then emits it from the first surface.

An optical sheet laminate10is provided so as to face the first surface of the diffusion plate9. The optical sheet laminate10includes the laminated sheets which include one transparent diffusion sheet that diffuses incoming light to homogenize luminance, and two transparent prism sheets that align respective directions of rays of the incoming light in a single direction,

The liquid-crystal panel1is disposed to face the first surface of the panel chassis8to close the entire opening of the panel chassis8. A periphery on the second surface of the liquid-crystal panel1is in contact with the first surface of the panel chassis8. In the liquid-crystal panel1, a surface far from the back chassis5(i.e., the first surface of the liquid-crystal panel1) is a display surface that displays an image.

A bezel11has a frame shape with an L-shaped cross section, and is provided to cover an outer circumferential surface of the panel chassis8and a periphery of the liquid-crystal panel1. That is, the liquid-crystal panel1is sandwiched between the panel chassis8and the bezel11. Note that the back chassis5, the panel chassis8, and the bezel11constitute a housing12.

As illustrated inFIG. 1, the enclosure2has a substantially box shape, and houses the liquid-crystal panel1, the diffusion plate9, the substrate4, and the housing12. The enclosure2has a frame-shaped architrave section21in the front of the enclosure2. Herein, an opening22is formed at the architrave section21, and allows the display surface of the liquid-crystal panel1to be viewed from the outside. The back chassis5partitions the internal space of the enclosure2such that along with the enclosure2, the back chassis5defines a first space S1at a backward of the back chassis5(outside the back chassis5), and a second space S2at a frontward of the back chassis5(inside the back chassis5). Here, the second space S2on the front side includes an internal space of the housing12, which is defined by the bottom plate section50, the side plate section52, and the diffusion plate9.

A first air inlet (air inlet)23and an air outlet24are formed at the side surfaces of the enclosure2. The first air inlet23and the air outlet24communicate the first space S1in the enclosure2with the outside of the enclosure2. Second air inlets25are also formed at the side surfaces of the enclosure2. The second air inlets25communicate the second space S2in the enclosure2with the outside of the enclosure2. Each of the first air inlet23, the second air inlets25, and the air outlet24has, for example, a slit shape and is extended over a corresponding side surface of the enclosure2.

In the present embodiment, the duct14is formed between the bottom plate section50of the back chassis5, and a facing section26of the enclosure that faces the bottom plate section50. In other words, the first space S1in the enclosure2accords with an internal space of the duct14, and the duct14is elongated from the first air inlet23through the air outlet24.

A fan (air flow generator)15that generates an air flow inside the duct14is disposed in the first space S1in the enclosure2. In the present embodiment, the fan15is disposed in the vicinity of the first air inlet23in the duct14in order to draw, inside the duct14, air from the first air inlet23. The type of fan15may be, for example an axial fan, or alternatively a centrifugal fan.

In the duct14, the fan15generates an air flow by which the Venturi effect that actively expels the air in the housing12from the first opening55occurs around the first opening55. The section configured to cause the Venturi effect to occur is called a venturi section140.

A light path in the liquid-crystal display apparatus100having the above-described structure will be described. Light emitted from each of the LEDs3passes through a corresponding through hole51, and then travels inside the housing12. The light traveling inside the housing12enters the diffusion plate9from the second surface directly or indirectly after being reflected by the reflection sheet13. The light traveling inside the diffusion plate9is diffused and homogenized inside the diffusion plate9, and then emitted from the first surface. The light homogenized by the diffusion plate9enters the optical sheet laminate10. As stated above, the light traveling inside the optical sheet laminate10is further homogenized, while respective traveling directions of rays of the light are aligned with a normal direction to the optical sheet laminate10. The light emitted from the optical sheet laminate10enters the liquid-crystal panel1from the second surface of the liquid-crystal panel1. The liquid-crystal panel1controls optical transmittance per pixel unit according to an input signal from an unillustrated control circuit, thereby causing the display surface to display an image according to the input signal.

An air flow in the liquid-crystal display apparatus100having the above structure will also be described. The fan15generates an air flow in the duct14(i.e., the first space S1). Specifically, the air drawn inside the duct14from the first air inlet23flows toward the air outlet24to exit outside the duct14from the air outlet24. In the second space S2, while the air therein is being expelled from the first opening55toward the first space S1by the Venturi effect, the air being drawn from the second openings56flows toward the first opening55. Here, a flow channel of the air expelled from the first opening55so as to flow from the inside to the outside of the housing12is called a first flow channel P1, while a flow channel of the air drawn from each of the second openings56so as to flow from the outside to the inside of the housing12is called a second flow channel P2.

The effects derived from the operation of the liquid-crystal display apparatus100stated above will be described.

As stated above, although displaying an image through the liquid-crystal display apparatus100needs to supply electric power to the LEDs3to be lit, part of the electric power supplied to the LEDs3is released inside the housing12as heat. The configuration of the present embodiment defines the first and second flow channels P1and P2as stated above, thereby making it possible to generate an air flow from the second openings56toward the first opening55such that air is drawn inside the housing12from the second openings56, and then expelled outside the housing12from the first opening55. The configuration therefore enables release, outside the housing12, of the internal air of the housing12heated by the heat from the LEDs3, thereby suppressing a rise in internal temperature of the housing12. The above configuration enables generation of an air flow inside the housing12without providing another fan15inside the housing12in particular. It is therefore possible to prevent enlargement of the housing12and improve heat dissipation ability.

In the present embodiment, the substrate4on which the LEDs3are mounted is disposed outside the housing12. The heat held by the LEDs3forming a heat source is transferred to the substrate4disposed outside the housing12. A rise in internal temperature of the housing12is therefore suppressed. The embodiment is also configured such that the respective optical axes of the LEDs3are positioned in the respective through holes51in the bottom plate section50of the housing12. Therefore, even if the substrate4is disposed outside the housing12, light emitted from each of the LEDs3passes through a corresponding through hole51in the bottom plate section50of the housing12, and then enters the inside of the housing12.

Also, in the present embodiment, the plate member6makes it possible to suppress the occurrence of a turbulent flow in the internal space S2of the housing12, namely a sudden change in the air flow from the second openings56toward the first opening55. In other words, it is possible to rectify the air flow in the internal space S2of the housing12. It is therefore possible to efficiently release the internal air of the housing12heated by the heat from the light sources, thereby suppressing a rise in the internal temperature of the housing12.

Various variations of the present embodiment will hereinafter be described with reference toFIGS. 3A to 4B.

FIG. 3Ais a cross-sectional view depicting a first variation of the plate member6inFIG. 2. A plate member6in the present variation contains a light scattering material. Here, the plate member6containing the light scattering material means that the plate member6is manufactured by curing a material in which particles that allow light to be scattered are dispersed.

The present variation makes it possible to successfully diffuse light inside a housing12to homogenize luminance of a liquid-crystal panel1as a result of the plate member6containing the light scattering material. Here, the plate member6containing the light scattering material means that optical scattering particles are dispersed in the material of the plate member6.

FIG. 3Bis a cross-sectional view depicting a second variation of the plate member6inFIG. 2. A plate member6in the present variation has an embossed surface that is an opposite surface of the plate member6from a surface of the plate member6facing a bottom plate section50.

The present variation makes it possible to successfully diffuse light inside a housing12to homogenize luminance of a liquid-crystal panel1as a result of the plate member6having a front surface that is embossed.

FIG. 3Cis a cross-sectional view depicting a third variation of the plate member6inFIG. 2. In the present variation, a plate member6is provided with optical diffusing lens structures on a front surface of the plate member6, each of which is formed along the optical axis of a corresponding LED3of LEDs3. Here, each optical diffusing lens structure means a structure having a function of diffusing light.

The present variation makes it possible to successfully diffuse light inside a housing12to further homogenize luminance of a liquid-crystal panel1as a result of the plate member6being provided with the optical diffusing lens structures.

FIG. 4Ais a schematic illustration depicting a first variation of the duct14on the back surface of the back chassis5inFIG. 1. In the present variation, fin-shaped projections57are formed on a bottom plate section50. The projections57constitute a folded structure in a duct14. The fin-shaped projections57are elongated from the bottom plate section50to a facing section26of an enclosure2facing the bottom plate section50, and in contact with the facing section26. That is, the duct14in the present variation is composed of the projections57between the bottom plate section50and the facing section26. Although not shown, a first air inlet23is formed at the proximal end of the duct14from a fan15, while an air outlet24is formed at the distal end of the duct14from the fan15. A venturi section140is formed at a position away from the fan15(proximal to the air outlet24).

The present variation enables an increase of the overall length of the duct14by one or more turns, thereby improving the effect of forced air cooling by an air flow in the duct14. The air flow in the duct14is necessary for exhibiting the Venturi effect in the venturi section140, and itself contributes to cooling the inside of the duct14and the vicinity of the duct14. Increasing the overall length of the duct14as shown by the structure of the present variation enables securing of a long flow channel for forced air cooling, thereby improving the cooling effect.

FIG. 4Bis a schematic illustration depicting a second variation of the duct14on the back surface of the back chassis5inFIG. 1. A duct14in the present variation may be divided into two parts. Two (pair of) fans15are accordingly provided, and first air inlets23, air outlets24, and venturi sections140are also provided one pair each. The effect by the present variation is similar to that by the first variation. Note that unlike the structure shown inFIGS. 4A and 4B, the duct14may have a swirl structure as a whole.

Instead of the present variation, fin-shaped projections may be formed on the facing section26of the enclosure2. In this case, the fin-shaped projections are elongated to the bottom plate section50and in contact with the bottom plate section50. Alternatively, fin-shaped projections may be formed on both the bottom plate section50and the facing section26of the enclosure2. In this case, projections on the bottom plate section50and projections on the facing section26are elongated such that their respective tips are in contact with each other.

Second Embodiment

FIG. 5is a cross-sectional view of a liquid-crystal display apparatus100according to a second embodiment. The liquid-crystal display apparatus100according to the present embodiment illustrated inFIG. 5has a back chassis5whose structure is different from that of the first embodiment. The embodiment has a similar configuration to that of the liquid-crystal display apparatus100according to the first embodiment inFIGS. 1 and 2, other than the configuration of the back chassis5. Therefore, the same components as those shown inFIGS. 1 and 2are denoted by the same reference numerals, and description thereof is omitted.

In the present embodiment, the back chassis5is separated into a first chassis58and a second chassis59in a side plate section52.

The first chassis58has a flange54, and the side plate section52, and an end of the side plate section52is bent parallel to a bottom plate section50. The second chassis59has the side plate section52, the bottom plate section50, and an elongated section53, and the end of the side plate section52are bent parallel to the bottom plate section50. The present embodiment differs from the first embodiment in that no through holes51are provided at the bottom plate section50and a substrate4is disposed inside a housing12. Specifically, the substrate4is disposed, with a reflection sheet13adhered to a surface of the substrate4, above an internal surface of the bottom plate section50, and screwed to the bottom plate section50.

In addition, a plate member6in the present embodiment is disposed parallel to the bottom plate section50between the first chassis58and the second chassis59. The reflection sheet13is also sandwiched between the plate member6and the side plate section52of the second chassis59.

A spacer16is provided between the first chassis58and the second chassis59, and the first chassis58and the second chassis59are separated from each other. The first chassis58and the second chassis59are screwed to each other through the plate member6, the reflection sheet13, and the spacer16.

In the present embodiment, gaps provided by the spacer16between the first chassis58and the second chassis59form a first opening55and a second opening56.

The substrate4may be disposed inside the housing12like the present embodiment. It is thereby possible to eliminate additional processing such as providing the through holes51in the bottom plate section50, and providing the first and second openings55and56in the side plate section52.

FIG. 6is a cross-sectional view of a liquid-crystal display apparatus100according to a variation of the second embodiment. In the present variation, a plate member6is disposed inside a first chassis58so as to face a diffusion plate9. That is, the present variation is provided with two plate members6.

The two plate members6may be provided like the present variation. The two plate members6enables improvement in rectification of an air flow from a second opening56toward a first opening55.

Third Embodiment

FIG. 7is a cross-sectional view of a liquid-crystal display apparatus100according to a third embodiment. The liquid-crystal display apparatus100according to the present embodiment illustrated inFIG. 7has a back chassis5whose configuration is different from that of the first embodiment. The present embodiment has a similar configuration to that of the liquid-crystal display apparatus100according to the first embodiment inFIGS. 1 and 2, other than the configuration of the back chassis5. Therefore, the same components as those shown inFIGS. 1 and 2are denoted by the same reference numerals, and description thereof is omitted.

In the present embodiment, the back chassis5is separated into a first chassis58and a second chassis59in the side plate section52.

The first chassis58has a flange54and the side plate section52. An end of the side plate section52is bent parallel to a bottom plate section50. The second chassis59has a rectangular plate shape with the bottom plate section50and an elongated section53. Specifically, part of the bottom plate section50is the elongated section53. In the present embodiment, like the first embodiment, through holes51are provided at the bottom plate section50and a substrate4is disposed outside a housing12. Specifically; the substrate4is disposed outside the bottom plate section50with a reflection sheet13adhered to a surface of the bottom plate section50, and screwed to the bottom plate section50.

A spacer16is provided between the first chassis58and the second chassis59, and the first chassis58and the second chassis59are separated from each other. The first chassis58and the second chassis59are screwed to each other through a plate member6, the reflection sheet13, and the spacer16.

In the present embodiment, gaps provided by the spacer16between the first chassis58and the second chassis59form a first opening55and a second opening56.

The second chassis59may be a simple plate member like the present embodiment. That is, the back chassis5may be formed by a simple configuration.

FIG. 8is a cross-sectional view f a liquid-crystal display apparatus100according to a variation of the third embodiment. A plate member6in the present variation is disposed inside a first chassis58so as to face a diffusion plate9. That is, the present variation includes two plate members6.

Two plate members6may be provided like the present variation. The two plate members6enables improvement in rectification of an air flow from a second opening56toward a first opening55.

Preferable embodiments of the present invention are shown below.

An illuminating device according to an embodiment of the present invention includes a substrate, a housing, a diffusion plate, a duct, an air flow generator, a venturi section, a first flow channel, and a second flow channel. The substrate has a surface on which light sources are mounted. The housing has a bottom plate section that holds the substrate, and a side plate section that surrounds the bottom plate section. Herein, an opening is defined by an end of the side plate section. The diffusion plate is disposed to face the bottom plate section, and closes the opening. The duct has an air inlet and an air outlet. The air flow generator generates an air flow inside the duct. The venturi section is formed between the air inlet and the air outlet of the duct such that an internal space of the housing closed with the diffusion plate communicates with an inside of the duct. The first flow channel is connected through a first opening provided at the bottom plate section or the side plate section. In the second flow channel, through a second opening provided in the bottom plate section or the side plate section, an outside of the housing is not connected to the duct but communicates with an inside of the housing.

In this configuration, the first flow channel is provided such that the internal space of the housing communicates with the venturi section in the duct through the first opening. The air flow is generated in the duct by the air flow generator. The Venturi effect accordingly occurs in the first flow channel such that the internal air of the housing is expelled outside the housing from the first opening along with the air flow in the duct. In the second flow channel, the internal space of the housing does not communicate with the inside of the duct through the second opening, and the Venturi effect does not occur unlike the above. The internal air of the housing is therefore not expelled outside the housing from the second opening. In other words, in the second flow channel, air outside the housing is drawn inside the housing from the second opening. Thus, it is possible to generate an air flow from the second opening toward the first opening such that in the internal space of the housing, air is drawn inside from the second opening and then expelled outside from the first opening. It is therefore possible to release, outside the housing, the internal air of the housing heated by heat from the light sources, thereby suppressing a rise in internal temperature of the housing. The above configuration enables generation of an air flow inside the housing without providing any air flow generator inside the housing in particular, thereby preventing enlargement of the housing and improving heat dissipation ability.

In one aspect, the duct may have one or more turns.

This configuration enables an increase of the overall length of the duct by the one or more turns, thereby improving the effect of forced air cooling by an air flow in the duct. The air flow in the duct is necessary for exhibiting the Venturi effect in the venturi section, and itself contributes to cooling the inside of the duct and the vicinity of the duct. Therefore, increasing the overall length of the duct like the above configuration enables securing of a long flow channel for forced air cooling and improvement in cooling effect.

In one aspect, through holes may be formed at the bottom plate section of the housing. The substrate is held by the bottom plate section of the housing outside the housing such that respective optical axes of the light sources correspond to the through holes.

In this configuration, the substrate on which the light sources are mounted is disposed outside the housing. Therefore, heat generated from the light sources is released outside the housing, and a rise in internal temperature of the housing is suppressed. Also, the respective axes of the light sources correspond to the through holes in the bottom plate section of the housing. Therefore, even if the substrate is disposed outside the housing, light emitted from each of the light sources passes through a corresponding through hole in the bottom plate section of the housing, and then enters the inside of the housing to strike a lighting target.

In one aspect, a plate member may be disposed to face the diffusion plate in the internal space of the housing.

In this configuration, the plate member makes it possible to suppress the occurrence of a turbulent flow in the internal space of the housing, namely a sudden change in the air flow from the second opening toward the first opening. In other words, it is possible to rectify the air flow in the internal space of the housing. It is therefore possible to release, outside the housing, the internal air of the housing heated by heat from the light sources, thereby suppressing a rise in internal temperature of the housing.

In one aspect, the plate member may contain a light scattering material.

This configuration makes it possible to successfully diffuse light inside the housing to homogenize luminance of the lighting target as a result of the plate member containing the light scattering material.

In one aspect, the plate member may have an embossed surface that is an opposite surface of the plate member from a surface of the plate member superposed on the bottom plate section.

This configuration makes it possible to successfully diffuse light inside the housing to homogenize luminance of the lighting target as a result of the plate member being provided with the embossed surface.

In one aspect, the plate member may be provided with optical diffusing lens structures, each of which is formed at a position along the optical axis of a corresponding light source of the light sources, on an opposite surface of the plate member from a surface of the plate member superposed on the bottom plate section.

This configuration makes it possible to successfully diffuse light inside the housing to homogenize luminance of the lighting target as a result of the plate member being provided with the optical diffusing lens structures.

A display apparatus according to an embodiment of the present invention includes the illuminating device, a display panel and an enclosure. The display panel has a display surface that displays an image. The display panel controls transmittance of light, incoming from an opposite surface of the display panel from the display surface through the diffusion plate, emitted from the light sources, thereby generating the image. The enclosure houses the display panel, the diffusion plate, the substrate, and the housing. The duct and the air flow generator are disposed between the bottom plate section and a facing section of the enclosure that faces the bottom plate section.

In this configuration, the structure of the illuminating device makes it possible to suppress a rise in internal temperature of the housing by heat generated from the light sources, thereby suppressing a rise in temperature of the display panel.

A display apparatus according to an embodiment of the present invention includes the illuminating device, a display panel and an enclosure. The display panel has a display surface that displays an image. The display panel controls transmittance of light, incoming from an opposite surface of the display panel from the display surface through the diffusion plate, emitted from the light sources, thereby generating the image. The enclosure houses the display panel, the diffusion plate, the substrate, and the housing, The air flow generator is disposed between the bottom plate section and a facing section of the enclosure that faces the bottom plate section. The duct is composed of fin-shaped projections formed on at least one of the bottom plate section, or the facing section.

In this configuration, the structure of the illuminating device makes it possible to suppress a rise in internal temperature of the housing by heat generated from the light sources, thereby suppressing a rise in temperature of the display panel. In addition, because the duct is composed of the fin-shaped projections formed on at least one of the bottom plate section, or the facing section, it is possible to form the duct by using the existing configuration without any new additional configuration.

Although as stated above specific embodiments of the present invention and variations thereof have been described, the present invention is not limited to the above embodiments, and may be implemented with various variations within the scope of the present invention. For example, an appropriate combination of contents of individual embodiments may be provided as an embodiment of the present invention.

REFERENCE SIGNS LIST

25Second air inlet

50Bottom plate section

52Side plate section