Illumination device

According to one embodiment, an illumination device includes a first light emitting element, a second light emitting element, an overcoat layer covering the first and second light emitting elements, a first transparent block disposed on the overcoat layer and overlapping the first light emitting element, a second transparent block disposed on the overcoat layer and overlapping the second light emitting element, and an optical sheet group disposed on the first transparent block and the second transparent block. A first side surface of the first transparent block and a second side surface of the second transparent block face each other. An air layer is interposed between the first side surface and the second side surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-134024, filed Aug. 19, 2021, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an illumination device.

BACKGROUND

A transmissive display device such as liquid crystal display devices comprises an illumination device overlapping a display panel. As the illumination device, a side-edge type illumination device comprising a light guide opposed to a display panel and light emitting elements arranged along a side surface of the light guide, and a direct type illumination device comprising light emitting elements arranged directly under a display panel are known.

On the other hand, local dimming is known as one of the control methods of an illumination device. When the illumination area of the minimum unit of local dimming is referred to as a segment, it is required that the areas of segments be reduced and the spread of light from each segment to the other adjacent segments be suppressed in order to achieve more precise local dimming.

DETAILED DESCRIPTION

In general, according to one embodiment, an illumination device includes, a circuit board, light emitting elements including a first light emitting element and a second light emitting element mounted on the circuit board, an overcoat layer being transparent and covering the circuit board and the light emitting elements, a first transparent block disposed on the overcoat layer and overlapping the first light emitting element, a second transparent block disposed on the overcoat layer, adjacent to the first transparent block, and overlapping the second light emitting element, and an optical sheet group disposed on the first transparent block and the second transparent block. A first side surface of the first transparent block and a second side surface of the second transparent block face each other. An air layer is interposed between the first side surface and the second side surface.

The disclosure is merely an example, and proper changes within the spirit of the invention which are easily conceivable by a person having ordinary skill in the art are included in the scope of the present invention as a matter of course. In addition, in some cases, in order to make the description clearer, the drawings may be produced more schematically than in the actual modes, but they are mere examples and do not limit the interpretation of the present invention. In the drawings, the reference symbols of the same or similar elements arranged sequentially may be omitted.

In the specification and drawings, the structural elements that have the same or similar functions as or to those described in connection with preceding drawings are denoted by the same reference symbols, and a detailed description thereof may be omitted.

In the present embodiment, a first direction X, a second direction Y, and a third direction Z are defined as illustrated in the drawings. The first direction X, the second direction Y, and the third direction Z are orthogonal to each other but may cross at an angle other than 90°. In the following description, viewing an X-Y plane defined by the first direction X and the second direction Y is referred to as planar view.

FIG.1is a schematic exploded perspective view of a display device DSP according to the present embodiment.

The display device DSP comprises an illumination device IL, a display panel PNL, a first polarizer PL1, and a second polarizer PL2. In the present embodiment, a liquid crystal display device is disclosed as an example of the display device DSP. The display panel PNL is, for example, a transmissive or transflective liquid crystal display panel. The display panel PNL is located between the first polarizer PL1and the second polarizer PL2.

The illumination device IL is opposed to the display panel PNL in the third direction Z. The illumination device IL emits light toward the display panel PNL and illuminates the display panel PNL. The illumination device IL of the example illustrated functions as a backlight unit of the display device DSP.

The display panel PNL comprises a first substrate SUB1, a second substrate SUB2, and a liquid crystal layer (not illustrated). The second substrate SUB2is opposed to the first substrate SUB1in the third direction Z. The liquid crystal layer is located between the first substrate SUB1and the second substrate SUB2. The display panel PNL comprises a display area DA where an image is displayed. The display area DA comprises pixels PX.

The pixels PX are arranged in a matrix in the first direction X and the second direction Y. Each of the pixels PX includes, for example, a red sub-pixel, a green sub-pixel, and a blue sub-pixel, although not described in detail. The sub-pixels each comprises a switching element, a pixel electrode connected to the switching element, and a common electrode opposed to the pixel electrode.

The first polarizer PL1is attached to the first substrate SUB1, and the second polarizer PL2is attached to the second substrate SUB2. The first polarizer PL1and the second polarizer PL2overlap the whole area of the display area DA in the third direction Z.

The illumination device IL is configured to illuminate at least the whole area of the display area DA of the display panel PNL. The display panel PNL is configured to display an image by selectively transmitting light emitted from the illumination device IL.

FIG.2is a schematic exploded perspective view of the illumination device IL according to the present embodiment.

The illumination device IL comprises a circuit board1, light emitting elements2, an overcoat layer3, a transparent block layer4, and an optical sheet group5.

The circuit board1comprises a circuit for driving the light emitting elements2, electrodes and various lines for mounting the light emitting elements2, etc.

The light emitting elements2are mounted on the circuit board1.

The overcoat layer3is located above the circuit board1and the light emitting elements2.

The transparent block layer4is located above the overcoat layer3. The transparent block layer4is composed of transparent blocks, which will be described in detail later.

The optical sheet group5is located above the transparent block layer4. For example, the optical sheet group5includes a diffusion sheet5A, a wavelength conversion sheet5B, a prism sheet5C, and a polarizing sheet5D. The diffusion sheet5A, the wavelength conversion sheet5B, the prism sheet5C, and the polarizing sheet5D are stacked in this order in the third direction Z. The optical sheet group5may not include at least one sheet of the above four sheets and may further include another sheet.

The circuit board1, the light emitting elements2, the overcoat layer3, the transparent block layer4, and the optical sheet group5are accommodated in a case10. The case10comprises a rear bezel11, a front bezel12, and a frame13. The rear bezel11and the front bezel12are formed of metallic materials, for example, aluminum or stainless steel.

The rear bezel11comprises a bottom plate11a, a pair of side plates11b, and a pair of side plates11c. The bottom plate11a, the pair of side plates11b, and the pair of side plates11care integrally formed.

The pair of side plates11beach extends in the second direction Y and is opposed in the first direction X. The pair of side plates11ceach extends in the first direction X and is opposed in the second direction Y. The pair of side plates11band the pair of side plates11care, for example, provided perpendicularly to the bottom plate11a.

The frame13is formed into a rectangular shape and provided along the pair of side plates11band the pair of side plates11c. The frame13is formed of, for example, a resin material.

The circuit board1, the overcoat layer3, the transparent block layer4, and the optical sheet group5are stacked in this order in the rear bezel11in the third direction Z. The front bezel12is coupled to the rear bezel11. The circuit board1, the overcoat layer3, the transparent block layer4, and the optical sheet group5are thereby held between the rear bezel11and the front bezel12.

The front bezel12comprises a rectangular opening OP. The display panel PNL illustrated inFIG.1is attached to the front bezel12with adhesive such as double-sided tape. At this time, the first polarizer PL1illustrated inFIG.1overlaps the opening OP.

FIG.3is a plan view illustrating the circuit board1, on which the light emitting elements2are mounted, and the transparent block layer4.

The light emitting elements2are arranged in a matrix in the first direction X and the second direction Y on an upper surface (mounting surface)1A of the circuit board1. The light emitting elements2are denoted by circles of solid lines in the figure, which do not represent their exact shapes. The pitch P1between the light emitting elements2arranged in the first direction X is constant, and the pitch P2between the light emitting elements2arranged in the second direction Y is constant. The pitch P1is equal to the pitch P2and is, for example, 6 mm.

In the present specification, the minimum unit of local dimming drive control is referred to as a driven unit6. Driven units6are denoted by quadrangles of alternate long and short dashed lines in the figure, which do not represent their exact shapes. To be specific, each of the driven units6comprises at least one light emitting element2and is configured to control the luminance of the at least one light emitting element2independently. In the example illustrated inFIG.3, each of the driven units6comprises one light emitting element2.

The transparent block layer4is composed of transparent blocks7. The transparent blocks7are arranged in a matrix in the first direction X and the second direction Y with extremely small gaps therebetween. Each of the transparent blocks7is disposed to correspond to one driven unit6. That is, one transparent block7is disposed to one driven unit6. In addition, each of the transparent blocks7overlaps one light emitting element2. The pitch between the transparent blocks7arranged in the first direction X is equal to the pitch P1of the light emitting elements2, and the pitch between the transparent blocks7arranged in the second direction Y is equal to the pitch P2of the light emitting elements2.

Each of the transparent blocks7is formed into a rectangular parallelepiped or cube and formed into a square shape in planar view. In addition, the lengths LX of the sides along the first direction X of the transparent blocks7are equal, and the lengths LY of the sides along the second direction Y of the transparent blocks7are also equal. The length LX is substantially equal to the pitch P1, and the length LY is substantially equal to the pitch P2. The transparent blocks7are made of resin such as acrylic resin or polycarbonate. The transparent blocks7may be made of glass.

FIG.4is a schematic cross-sectional view of the illumination device IL including the light emitting elements2and the transparent blocks7illustrated inFIG.3.FIG.4illustrates three light emitting elements21to23arranged in the first direction X of the light emitting elements2and three transparent blocks71to73arranged in the first direction X of the transparent blocks7.

The frame13is fixed to the side plates lib by double-sided tape T1. The frame13is also fixed to the side plates11cby double-sided tape, although not illustrated in the figure. The circuit board1, the overcoat layer3, and the transparent blocks7are disposed in an inner space surrounded by the frame13. The diffusion sheet5A, the wavelength conversion sheet5B, the prism sheet5C, and the polarizing sheet5D are disposed on the frame13. The sheet at the bottom of the optical sheet group5(i.e., the diffusion sheet5A in the example illustrated) is fixed to the frame13by double-sided tape T2.

The circuit board1is disposed on the bottom plate11aand fixed to the bottom plate11aby double-sided tape T3. The circuit board1is, for example, a flexible printed circuit board but may be a rigid printed circuit board.

The light emitting elements21to23are mounted on the circuit board1at regular pitches. A driven unit61comprises the light emitting element21. A driven unit62comprises the light emitting element22. A driven unit63comprises the light emitting element23. The luminance of the light emitting element21, the luminance of the light emitting element22, and the luminance of the light emitting element23are controlled independently in different driven units.

The light emitting elements2including the light emitting elements21to23are extremely small light emitting diodes (LEDs). Each of the light emitting elements2is, for example, a mini-LED with one side longer than 100 μm but shorter than 300 μm. The light emitting elements2are blue light emitting diodes which emit blue light.

The overcoat layer3directly covers the circuit board1and the light emitting elements21to23. That is, the overcoat layer3contacts the circuit board1and the light emitting elements21to23. The overcoat layer3is a transparent resin layer and has a sufficient thickness to cover the light emitting elements21to23.

For example, the overcoat layer3is formed of acrylic resin and has a thickness of 400 μm. An upper surface3A of the overcoat layer3is a substantially flat surface along the X-Y plane. The overcoat layer3prevents all the light emitting elements2including the light emitting elements21to23from falling off the circuit board1.

The transparent blocks7including the transparent blocks71to73are disposed on the overcoat layer3. As described above, each of the transparent blocks7overlaps one light emitting element2. In the example illustrated, the transparent block71overlaps the light emitting element21of the driven unit61, the transparent block72overlaps the light emitting element22of the driven unit62, and the transparent block73overlaps the light emitting element23of the driven unit63.

In addition, as described above, each of the transparent blocks7is a rectangular parallelepiped or a cube, and the side surfaces of the transparent blocks7are planes substantially perpendicular to the upper surface3A of the overcoat layer3. In the example illustrated, a side surface S1of the transparent block71and a side surface S2of the transparent block72are planes substantially parallel to each other and face each other with an air layer interposed therebetween. In addition, a side surface S3of the transparent block72and a side surface S4of the transparent block73are planes substantially parallel to each other and face each other with an air layer interposed therebetween.

In the example illustrated, an air layer is interposed between the transparent blocks71to73and the diffusion sheet5A, but the diffusion sheet5A may contact the transparent blocks71to73.

The wavelength conversion sheet5B has the function of absorbing light emitted from the light emitting elements2and converting into light of a wavelength longer than that of the absorbed light. The wavelength conversion sheet5B is, for example, a phosphor sheet in which a phosphor is dispersed, and converts blue light emitted from the light emitting elements2into white light. The wavelength conversion sheet5B may include quantum dots as a light emitting material.

The prism sheet5C has the function of condensing light transmitted through the wavelength conversion sheet5B. The prism sheet5C comprises prisms on its surface opposed to the polarizing sheet5D. The prism sheet5C may be composed of two prism sheets, for example, one prism sheet comprising prisms extending in the first direction X and the other prism sheet comprising prisms extending in the second direction Y.

The polarizing sheet5D is, for example, a reflective polarizing film. The polarizing sheet5D transmits a polarization component having a predetermined polarization axis of light transmitted through the prism sheet5C.

In the above-described illumination device IL, an optical path in a case where the light emitting element22turns on will be explained. The optical path is denoted by arrows in the figure, which do not represent the exact optical path due to the scale of the figure.

Blue light emitted from the light emitting element22is transmitted through the overcoat layer3and incident on the transparent block72. Blue light propagated through the transparent block72is totally reflected by the interfaces between the transparent block72and the air layers. That is, in the example illustrated, blue light propagated through the transparent block72is reflected by each of the side surfaces S2and S3. On the other hand, light entering at an angle that does not satisfy the condition of total reflection, i.e., light entering at an angle smaller than the critical angle, of blue light propagated toward the side surfaces S2and S3is transmitted through the transparent block72.

Blue light totally reflected by the transparent block72is emitted from an upper surface72A of the transparent block72and diffused moderately in the diffusion sheet5A. Blue light transmitted through the diffusion sheet5A is converted into white light in the wavelength conversion sheet5B. Then, white light is condensed moderately in the prism sheet5C, and only a predetermined polarization component of white light is transmitted through the polarizing sheet5D.

In this manner, when the light emitting element22of the driven unit62turns on, light transmitted through the transparent block72corresponding to the driven unit62can form illumination light L directly above the driven unit62. In addition, the undesirable spread of light to the adjacent transparent blocks71and73can be suppressed. That is, the spread of the illumination light L to the areas directly above the adjacent driven units61and63is suppressed.

In short, when the illumination area of the minimum unit of local dimming is referred to as a segment, each of the transparent blocks7can form one segment in planar view of the illumination device IL. In addition, when one transparent block7is disposed for each of the driven units6, one segment is formed for each of the driven units6.

A case where no air layer is interposed between the transparent blocks71to73will be described herein as a comparative example. That is, in the comparative example, a single transparent block overlaps the light emitting elements21to23. In this case, blue light emitted from the light emitting element22is transmitted through the overcoat layer3, and then spreads in the transparent block72along an optical path indicated by dotted lines in the figure. That is, illumination light spreads to the areas directly above the adjacent driven units61and63, as well as the area directly above the driven unit62, which causes enlargement of segments. In addition, the undesirable spread of illumination light causes degradation in the luminance of illumination light in the area directly above the driven unit62.

In this manner, the present embodiment can achieve desired luminance in each segment and further enable precise local dimming, compared to the comparative example.

Moreover, the segments can be more ramified by making the pitches P1and P2of the light emitting elements2smaller and making the lengths LX and LY of each side of the transparent blocks7shorter.

The thicknesses of the air layers interposed between the transparent blocks7, that is, the gaps G1and G2between the side surfaces facing each other, are greater than 0 μm. In order to ensure total reflection of light propagated through the transparent blocks7, the gaps G1and G2should be at least 20 μm or more. On the other hand, if the gaps between the adjacent transparent blocks7are too large, they may be recognized as black stripes. It is therefore preferable that the gaps G1and G2be 100 μm or less.

In addition, in order to suppress undesirable scattering or light leakage in each surface of the transparent blocks7, it is preferable that the side surfaces, the lower surfaces contacting the overcoat layer3, and the upper surfaces opposed to the diffusion sheet5A be each given a mirror finish.

In the explanation herein, for example, the light emitting element21corresponds to a first light emitting element, the light emitting element22corresponds to a second light emitting element, the transparent block71corresponds to a first transparent block, the transparent block72corresponds to a second transparent block, the side surface S1corresponds to a first side surface, and the side surface S2corresponds to a second side surface.

Another configuration example will be described next.

FIG.5is another plan view illustrating the circuit board1, on which the light emitting elements2are mounted, and the transparent block layer4. The light emitting elements2are denoted by circles of solid lines, the driven units6are denoted by quadrangles of alternate long and short dashed lines, and the transparent blocks7are denoted by quadrangles of solid lines.

The configuration example illustrated inFIG.5is different from the configuration example illustrated inFIG.3in that each of the driven units6comprises four light emitting elements2. In each of the driven units6, two light emitting elements2are arranged in the first direction X and two light emitting elements2are arranged in the second direction Y. These four light emitting elements2are, for example, electrically connected in series, and controlled together to have the same luminance.

In each of the driven units6, the pitch P1between the two light emitting elements2arranged in the first direction X is constant, and the pitch P2between the two light emitting elements2arranged in the second direction Y is constant. The pitch P1is equal to the pitch P2and is, for example, 6 mm.

In the two driven units6adjacent to each other in the first direction X, the pitch between the light emitting element2of one driven unit6and the light emitting element2of the other driven unit6is also equal to the above the pitch P1.

In the two driven units6adjacent to each other in the second direction Y, the pitch between the light emitting element2of one driven unit6and the light emitting element2of the other driven unit6is also equal to the above pitch P2.

The transparent blocks7are arranged in a matrix in the first direction X and the second direction Y with extremely small gaps therebetween. Each of the transparent blocks7is disposed to correspond to one driven unit6. That is, one transparent block7is disposed to one driven unit6. In addition, one transparent block7overlaps four light emitting elements2.

Each of the transparent blocks7is formed into a rectangular parallelepiped or cube, and formed into a square shape in planar view. In addition, the lengths LX of the sides along the first direction X of the transparent blocks7are equal, and the lengths LY of the sides along the second direction Y of the transparent blocks7are also equal. The length LX is substantially twice the pitch P1, and the length LY is substantially twice the pitch P2.

FIG.6is a schematic cross-sectional view of the illumination device IL including the light emitting elements2and the transparent blocks7illustrated inFIG.3.FIG.6illustrates six light emitting elements21to26arranged in the first direction X of the light emitting elements2and the three transparent blocks71to73arranged in the first direction X of the transparent blocks7.

The light emitting elements21to26are mounted at regular pitches on the circuit board1. The driven unit61comprises the light emitting elements21and22. The driven unit62comprises the light emitting elements23and24. The driven unit63comprises the light emitting elements25and26.

The overcoat layer3directly covers the circuit board1and the light emitting elements21to26.

The transparent blocks7including the transparent blocks71to73are disposed on the overcoat layer3. In the example illustrated, the transparent block71is disposed to correspond to the driven unit61and overlaps the light emitting elements21and22. The transparent block72is disposed to correspond to the driven unit62and overlaps the light emitting elements23and24. The transparent block73is disposed to correspond to the driven unit63and overlaps the light emitting elements25and26.

The side surface S1of the transparent block71and the side surface S2of the transparent block72are planes substantially parallel to each other and face each other with the air layer interposed therebetween. In addition, the side surface S3of the transparent block72and the side surface S4of the transparent block73are planes substantially parallel to each other and face each other with the air layer interposed therebetween.

In the example illustrated, the air layer is interposed between the transparent blocks71to73and the diffusion sheet5A, but the diffusion sheet5A may contact the transparent blocks71to73.

This configuration example also can achieve the same advantages as those described above. In addition, since light emitting elements2overlap one transparent blocks7, the segment formed by one transparent block7can have high luminance. Moreover, if the pitch between the light emitting elements2is equal to that of the configuration example illustrated inFIG.3, the area of each of the transparent blocks7increases approximately fourfold in planar view, and the segments can be enlarged.

FIG.7is another plan view illustrating the circuit board1, on which the light emitting elements2are mounted, and the transparent block layer4. The light emitting elements2are denoted by circles of solid lines, the driven units6are denoted by quadrangles of alternate long and short dashed lines, and the transparent blocks7are denoted by quadrangles of solid lines.

The configuration example illustrated inFIG.7is different from the configuration example illustrated inFIG.5in that the driven units6and the transparent blocks7are staggered. For example, regarding the arrangement of the transparent blocks7, the transparent blocks7arranged in the first direction X are shifted by half the pitch in the second direction Y. Each of the transparent blocks7is adjacent to the surrounding six transparent blocks7.

Each of the transparent blocks7is disposed to correspond to one driven unit6and overlaps four light emitting elements2.

This configuration example also can achieve the same advantages as those described above. In addition, when forming an illumination area having a curved edge, the edge can be smoothed.

FIG.8is another plan view illustrating the circuit board1, on which the light emitting elements2are mounted, and the transparent block layer4. The light emitting elements2are denoted by circles of solid lines, the driven units6are denoted by quadrangles of alternate long and short dashed lines, and the transparent blocks7are denoted by quadrangles of solid lines.

The configuration example illustrated inFIG.8is different from the configuration example illustrated inFIG.5in that transparent blocks7are disposed for each of the driven units6. For example, a driven unit6A in the figure comprises four light emitting elements2A,2B,2C, and2D. That is, the luminance of each of the light emitting elements2A,2B,2C, and2D are controlled in the same driven unit6A.

For the driven unit6A, four transparent blocks7A,7B,7C, and7D are disposed. The transparent block7A overlaps the light emitting element2A, the transparent block7B overlaps the light emitting element2B, the transparent block7C overlaps the light emitting element2C, and the transparent block7D overlaps the light emitting element2D.

From another point of view, each of the transparent blocks7is disposed to extend over light emitting elements2of driven units6. For example, the transparent block7A in the figure is disposed to extend over four driven units6A,6E,6F, and6G. In addition, the transparent block7A overlaps the light emitting element2A of the driven unit6A, a light emitting element2E of the driven unit6E, a light emitting element2F of the driven unit6F, and a light emitting element2G of the driven unit6G. That is, the luminance of each of the four light emitting elements2overlapping one transparent block7is controlled independently in different driven units.

In this configuration example, when the light emitting elements2A,2B,2C, and2D of the driven unit6A turn on, light emitted from the light emitting elements2A,2B,2C, and2D propagates through the four transparent blocks7A,7B,7C, and7D and forms illumination light. That is, the segment corresponding to the area of four transparent blocks7can be formed by turning on one driven unit6.

Thus, this configuration example also can achieve the same advantages as those described above and can form large segments with low energy consumption.

In the configuration example illustrated inFIG.8, for example, the light emitting element2A corresponds to a first light emitting element, the light emitting element2B corresponds to a second light emitting element, the transparent block7A corresponds to a first transparent block, and the transparent block7B corresponds to a second transparent block.

FIG.9is another cross-sectional view of the illumination device IL including the light emitting elements2and the transparent blocks7illustrated inFIG.3.

The configuration example illustrated inFIG.9is different from the configuration example illustrated inFIG.4in that a transparent film8is attached to the transparent blocks7constituting the transparent block layer4. A transparent adhesive layer AD attaches the transparent blocks7and the transparent film8to each other. This suppresses a shift in the positions of the transparent blocks7with respect to each other. In addition, the transparent film8is fixed to the frame13by double-sided tape14. This suppresses a shift in the positions of the light emitting elements2and the transparent blocks7with respect to each other.

The optical sheet group5is stacked on the transparent film8.

The transparent blocks7and the transparent film8can be attached to each other also in the other configuration examples described above.

An experiment for measuring luminance in a case where light emitting elements turn on will be described next.

The experiment was carried out under the following conditions: nine driven units6are arranged in the first direction X, and the pitch between the light emitting elements2arranged in the first direction X of the driven units6is 6 mm.

In the present embodiment, the transparent blocks7are provided to correspond to the driven units6, respectively, as illustrated in the upper tier. The length of one side of the transparent blocks7is 12 mm.

In comparative example 1, each transparent block7is provided to correspond to three driven units6as illustrated in the middle tier. The length of one side of the transparent blocks7is 36 mm.

In comparative example 2, each transparent block7is provided to correspond to nine driven units6as illustrated in the lower tier.

In the present embodiment and comparative examples 1 and 2, the luminance in a case where only the two light emitting elements2of the central driven unit6turn on was measured.

FIG.10is a diagram illustrating the measurement results of the luminance. “A” in the figure represents the measurement result of the luminance in the present embodiment, “Cl” represents the measurement result of the luminance in comparative example 1, and “C2” is represents the measurement result of the luminance in comparative example 2.

When comparative examples 1 and 2 are compared, the luminance decreases at the boundaries between the transparent blocks7in comparative example 1. That is, it has been confirmed that the spread of illumination light to the adjacent transparent blocks7(or the spread of illumination light to the areas directly above the adjacent driven units6) can be suppressed by arranging the transparent blocks7.

In addition, when the present embodiment and comparative example 1 are compared, it has been confirmed that in the present embodiment, when the maximum luminance in the area directly above the turning on light emitting elements2is one, the luminance at the boundaries with the adjacent transparent blocks7is approximately ½, and the spread of illumination light can be further suppressed.

For reference, in the present embodiment and comparative examples 1 and 2, the luminance of illumination light in a case where all the light emitting elements2turn on was measured to confirm that equivalent luminance was achieved.

Furthermore, in the present embodiment and comparative examples 1 and 2, the color chromaticity of illumination light in a case where all the light emitting elements2turn on was measured to confirm that equivalent color chromaticity was achieved.

In the above-described embodiment, the case where the transparent blocks7are formed into a square shape in planar view has been described. However, the transparent blocks7may be formed into a rectangular shape, a polygonal shape other than a quadrangle, a circular shape, or an elliptical shape. Each of the side surfaces of the transparent blocks7is not limited to a plane and may be a curved surface.

Moreover, at least one of the double-sided tape T1to14may be replaced by another adhesive member.

All of the illumination devices and display devices that can be embodied by making design changes to the illumination devices and display devices described as the embodiments of the present invention as appropriate by a person having ordinary skill in the art also fall within the scope of the present invention as long as they are in keeping with the spirit of the present invention.

Various modifications are easily conceivable within the category of the ideas of the present invention by a person having ordinary skill in the art, and the modifications are also considered to fall within the scope of the present invention. For example, additions, deletions or changes in design of the structural elements, or additions, omissions or changes in condition of the processes conducted as appropriate by a person having ordinary skill in the art in the above embodiments fall within the scope of the present invention as long as they are in keeping with the spirit of the present invention.

In addition, the other advantages of the aspects described in the embodiments, which are obvious from the descriptions of the present specification, or which can be conceived as appropriate by a person having ordinary skill in the art, are considered to be achievable by the present invention as a matter of course.