JP4478873B2 - Surface light source device and image display device - Google Patents

Description

  The present invention relates to a technical field regarding a surface light source device and an image display device. More specifically, the present invention relates to a technical field for preventing uneven illumination without forming a diffusion plate in a predetermined shape and causing a decrease in luminance.

  The image display device includes, for example, a light source and a light modulation element that modulates the light emitted from the light source, and displays the image obtained by irradiating the light modulation element with the light emitted from the light source and modulating the light. There is something to do.

  In such an image display device, for example, a liquid crystal panel having a liquid crystal is used as a light modulation element, and a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED) is used as a light source. In some cases, a light source is disposed as a backlight on the back side of the light modulation element, and light emitted from the light source is modulated by the light modulation element to generate an image on the display panel.

  The backlight includes a so-called side edge type that is disposed on the side of a light guide plate (diffusion plate) provided on the back side of the display panel, and a so-called direct type that is disposed on the back side of the display panel. There is a type called.

  Side edge type backlights are widely used in notebook personal computers and the like that are particularly required to be thin. On the other hand, direct type backlights are widely used for television displays and the like because of the necessity of obtaining a bright image with high contrast and the necessity of maintaining high luminance even in long-term use.

  An example of a conventional image display device having a direct type backlight is shown below (see FIG. 11).

  As the backlight that is the light sources a, a,..., For example, a plurality of the cold cathode fluorescent lamps described above are used. The light sources a, a,... Are formed in a cylindrical shape that is long in one direction, and are attached to side portions c, c of a lamp housing b that forms a shallow box shape in which both ends in the longitudinal direction are opened in one direction. . In this way, the light sources a, a,... Attached to the lamp housing b are arranged at equal intervals in a parallel state in the lamp housing b.

  A diffusion plate e is attached to the lamp housing b so as to close the opening d. The diffusing plate e is formed of a transparent or milky white flat resin material, and has a function of diffusing light emitted from the light sources a, a,.

  Various optical sheets f, f, f are arranged at positions opposite to the light sources a, a,. The optical sheets f, f, and f have various functions such as a polarization function, a diffusion function, and a brightness enhancement function.

  For example, a liquid crystal panel (not shown) having a liquid crystal as a spatial light modulation element is disposed at a position on the opposite side of the diffusion plate e across the optical sheets f, f, and f.

  Thus, the image display device is configured by sequentially arranging the lamp housing b to which the liquid crystal panel, the optical sheets f, f, f, the diffusion plate e, and the light sources a, a,.

  By the way, in the image display device configured as described above, since the diffusion plate e is formed in a flat plate shape, the distance between each part of the diffusion plate e and the light sources a, a,. In contrast, the brightness of each part of the diffuser plate e is different, so that there is a problem that so-called illumination unevenness occurs due to the presence of a bright part and a dark part.

  That is, as shown in FIG. 12, the distance between each point A, B, C of the diffuser plate e and the light source a is the shortest distance between the point A and the light source a and increases as the distance from the point A increases. Since the luminous flux density decreases in inverse proportion to the square of the distance, the luminance at point A is maximized, the luminance decreases in order at points B and C, the portion at point A is the brightest, and the portions at point B and point C become darker in sequence. As a result, uneven illumination occurs.

  Therefore, as an image display device that prevents the occurrence of such illumination unevenness, surfaces that face the light source of the diffusion plate are alternately formed on the uneven surface, and the luminance in each part of the diffusion plate is made substantially uniform, so Some have been designed to prevent the occurrence (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2003-279978

  However, in the image display device described in Patent Document 1, the surface of the diffusion plate facing the light source is alternately formed on the uneven surface, and the thickness of the diffusion plate is uneven, There is a problem in that a light amount is lost as compared with a thin portion, and the light use efficiency is lowered.

  When such a loss of light intensity occurs, it becomes difficult to use for a television display or the like that needs to obtain a bright image as described above. For this reason, it is conceivable to use a high-luminance light source in order to improve the luminance. However, in this case, a new problem such as an increase in power consumption occurs.

  Accordingly, it is an object of the surface light source device and the image display device of the present invention to overcome the above-described problems and prevent the occurrence of illumination unevenness without causing a decrease in luminance.

In order to solve the above-described problems, the surface light source device of the present invention includes a plurality of light sources arranged to be held by a lamp housing, a diffusion plate arranged to face the light sources and diffusing light emitted from the light sources, And an optical sheet disposed on the opposite side of the light source across the diffusion plate, and the diffusion plate is formed in a shape having a substantially uniform thickness with a plurality of recesses and a plurality of protrusions alternately continuous. Each part of the surface facing the light source of the diffuser plate is made to be a concave curved surface, and a light source having no radiant flux density anisotropy is used as the light source. The distance from the light source located closest to each part is set to be substantially the same distance, and a reflection surface formed in a planar shape for reflecting light emitted from the light source toward the diffusion plate is provided at a position facing the diffusion plate, Each part of the surface of the diffuser facing the light source and each of the parts In which the most to across the reflecting surface positioned near the light source a distance between the opposite side of the imaginary light source to substantially the same distance, and such luminance is substantially uniform in all parts of the surface facing the light source of the diffuser plate is there.

In order to solve the above-described problem, the image display device of the present invention has a plurality of light sources that are held and arranged in the lamp housing, and a diffusion plate that is arranged to face the light sources and diffuses the light emitted from the light sources. An optical sheet disposed on the opposite side of the light source with the diffusion plate interposed therebetween, and a spatial light modulation element disposed on the opposite side of the optical sheet with the diffusion plate interposed therebetween. The projections of the diffuser plate are alternately formed in a shape having a substantially uniform thickness, and the portions facing the light sources among the surfaces facing the light sources of the diffuser plate are concavely curved, so that the radiant flux density is different as the light source. Using a light source having no directivity, the distance between each part of the surface facing the light source of the diffuser plate and the light source located closest to each part is made substantially the same distance, and the light source is emitted to a position facing the diffuser plate. A plane that reflects light toward the diffuser The diffuser plate is provided with a reflection surface, and the distance between the light source and the imaginary light source on the opposite side across the reflection surface located closest to each part of the surface of the diffuser plate facing the light source is made substantially the same. The luminance of the entire surface of the surface facing the light source is substantially uniform .

  Therefore, in the surface light source device and the image display device of the present invention, the light transmittance in each part of the diffusion plate is substantially uniform, and the difference in the distance between each part of the diffusion plate and the light source is reduced.

The surface light source device of the present invention includes a plurality of light sources arranged to be held by a lamp housing, a diffusion plate arranged to face the light source and diffusing light emitted from the light source, and a light source of the light source sandwiched between the diffusion plates. An optical sheet disposed on the opposite side, wherein the diffusion plate is formed in a shape in which a plurality of recesses and a plurality of protrusions are alternately continuous and have a substantially uniform thickness, and the surface of the diffusion plate facing the light source Each part facing each light source has a concave curved surface , a light source having no radiant flux density anisotropy is used as the light source, and each part of the surface facing the light source of the diffuser and the light source located closest to each part Each part of the surface of the diffuser plate facing the light source is provided with a reflective surface formed in a flat shape that reflects the light emitted from the light source toward the diffuser plate at a position facing the diffuser plate. And the reflective surface located closest to each part Nde to approximately the same distance the distance between the opposite side of the imaginary light source and the light source, characterized in that as the luminance is substantially uniform in all parts of the surface facing the light source of the diffusion plate.

  Therefore, since the concave curved surface is positioned opposite to each light source, the difference in luminance at each part of the diffuser plate is reduced, the occurrence of uneven illumination is prevented, and the thickness of the diffuser plate is substantially uniform. The luminance can be improved without causing a decrease in the brightness.

And since the brightness | luminance was made substantially uniform in all the parts of the surface which faces the light source of a diffuser plate, generation | occurrence | production of illumination nonuniformity can be prevented reliably.

That is, a light source having no radiant flux density anisotropy is used as the light source, and the distance between each part of the surface of the diffusion plate facing the light source and the light source located closest to each part is set to be approximately the same distance. The occurrence of unevenness can be prevented with a high probability.

In addition, a reflection surface formed in a planar shape that reflects light emitted from the light source toward the diffusion plate at a position facing the diffusion plate is provided, and each part of the surface of the diffusion plate facing the light source and the nearest part of each part Since the distance between the light source and the imaginary light source on the opposite side across the reflecting surface is set to be substantially the same distance, it is possible not only to prevent uneven illumination with a higher probability, but also to reduce the thickness of the surface light source device. .

In the invention described in claim 2 , since a gap is formed between the optical sheet and the diffusion plate, it is difficult to visually recognize the shape of the diffusion plate from the outside, and the optical sheet is diffused through the air layer. Since the plate is opposed to the light, it is difficult for the light to travel in an unnecessary direction, and it is difficult to cause inconveniences such as a decrease in light use efficiency.

In the invention described in claim 3 , since the reflection surface for reflecting the light emitted from the plurality of light sources is formed on the housing and the plurality of light sources are attached to the reflection surface, the light emitted from the light source Since most of the light is directly incident on the diffuser plate, the shape of the diffuser plate can be designed with little consideration of the light reflected and incident on the diffuser plate, and the design can be facilitated. .

The image display apparatus according to the present invention includes a plurality of light sources arranged to be held by a lamp housing, a diffusion plate arranged to face the light sources and diffusing light emitted from the light source, and a light source sandwiched between the diffusion plates. An optical sheet disposed on the opposite side and a spatial light modulator disposed on the opposite side of the optical sheet with the diffusion plate interposed therebetween, wherein the diffusion plate includes a plurality of recesses and a plurality of protrusions alternately arranged. Use a light source that does not have radiant flux density anisotropy as a light source. The distance between each part of the surface of the diffuser plate facing the light source and the light source located closest to each part is made substantially the same distance, and the light emitted from the light source is reflected toward the diffuser plate at a position facing the diffuser plate. A flat reflecting surface is provided and expanded. The distance between each part of the surface facing the light source of the plate and the light source opposite to the imaginary light source on the opposite side across the reflecting surface located closest to each part is made substantially the same distance, and in all parts of the surface facing the light source of the diffusion plate The brightness is made substantially uniform .

  Therefore, since the concave curved surface is positioned opposite to each light source, the difference in luminance at each part of the diffuser plate is reduced, the occurrence of uneven illumination is prevented, and the thickness of the diffuser plate is substantially uniform. The luminance can be improved without causing a decrease in the brightness.

And since the brightness | luminance was made substantially uniform in all the parts of the surface which faces the light source of a diffuser plate, generation | occurrence | production of illumination nonuniformity can be prevented reliably.

That is, a light source having no radiant flux density anisotropy is used as the light source, and the distance between each part of the surface of the diffusion plate facing the light source and the light source located closest to each part is set to be approximately the same distance. The occurrence of unevenness can be prevented with a high probability.

In addition, a reflection surface formed in a planar shape that reflects light emitted from the light source toward the diffusion plate at a position facing the diffusion plate is provided, and each part of the surface of the diffusion plate facing the light source and the nearest part of each part Since the distance between the light source and the imaginary light source on the opposite side across the reflecting surface is set to be substantially the same distance, it is possible not only to prevent uneven illumination with a higher probability, but also to reduce the thickness of the surface light source device. .

In the invention described in claim 5 , since a gap is formed between the optical sheet and the diffusion plate, it is difficult to visually recognize the shape of the diffusion plate from the outside, and the optical sheet and the diffusion are diffused through an air layer. Since the plate is opposed to the light, it is difficult for the light to travel in an unnecessary direction, and it is difficult to cause inconveniences such as a decrease in light use efficiency.

In the invention described in claim 6 , since the reflecting surface for reflecting the light emitted from the plurality of light sources is formed on the housing and the plurality of light sources are attached to the reflecting surface, the light emitted from the light sources Since most of the light is directly incident on the diffuser plate, the shape of the diffuser plate can be designed with little consideration of the light reflected and incident on the diffuser plate, and the design can be facilitated. .

  The best mode of the surface light source device and the image display device of the present invention will be described below with reference to the accompanying drawings. The best mode shown below was obtained by providing the image display device of the present invention with a liquid crystal panel as a spatial light modulation element for modulating light, and irradiating the liquid crystal panel with light emitted from a light source. The present invention is applied to an image display device that displays an image, and the surface light source device of the present invention is applied to a surface light source device used in such an image display device.

  The image display device 1 is, for example, a television device including a flat display, and includes a device main body 2 and speaker units 3 and 3 disposed on both sides of the device main body 2. It is supported by a stand 4 (see FIG. 1).

  A front panel 5 formed in a transparent flat plate shape is provided on the front surface of the apparatus body 2, and various parts such as a liquid crystal panel are disposed on the back side of the front panel 5.

  The apparatus main body 2 includes a surface light source device 6 and a liquid crystal panel 7 having a liquid crystal functioning as a spatial light modulation element. The surface light source device 6 is provided with light sources 8, 8,... As shown in FIG. A lamp housing 9, a diffusion plate 10, and optical sheets 11, 11, 11.

  As the light sources 8, 8,..., For example, a cold cathode fluorescent lamp (CCFL) is used, and the light sources 8, 8,... Are formed in a long cylindrical shape in one direction.

  The lamp housing 9 is formed in a shallow box shape opened to the front, and includes a bottom surface portion 9a and peripheral surface portions 9b, 9b,... Provided on the periphery of the bottom surface portion 9a. The inner surface (front surface) of the bottom surface portion 9a is formed as a reflection surface 9c that reflects light emitted from the light sources 8, 8,. The both end portions in the longitudinal direction of the light sources 8, 8,... Are attached to the circumferential surface portions 9b, 9b that are positioned to face each other.

  The light sources 8, 8,... Attached to the lamp housing 9 in this way are arranged at equal intervals in a state parallel to each other in the lamp housing 9.

  The diffusion plate 10 is made of a transparent or milky white resin material, for example, an acrylic resin or a polycarbonate resin, and the like, and the concave portions 12, 12,... And the protrusions 13, 13,. It is formed in a corrugated plate shape. Are aligned with the alignment direction of the light sources 8, 8,... (See FIGS. 2 and 3). The inner surface 10a of the diffusing plate 10, that is, the surface facing the light sources 8, 8,..., Has portions corresponding to the protrusions 13, 13,. , 12,... Are projected surfaces 12a, 12a,.

  The diffusion plate 10 is attached so as to close the opening 9d of the lamp housing 9 so that the concave curved surfaces 13a, 13a,... Face the light sources 8, 8,.

  Hereinafter, an example of a method for forming a specific shape of the diffusion plate 10 will be described (see FIGS. 4 and 5).

  First, of the light emitted from the light sources 8, 8,..., The light that is directly incident on the diffusion plate is considered (see FIG. 4). Are assumed to be light sources having no radiant flux density anisotropy, that is, light sources having a uniform light intensity distribution in all light emitting directions.

  Since the intensity of light emitted from the light sources 8, 8,... Decreases in inverse proportion to the square of the distance, as shown in FIG. A set of points equidistant from. For example, FIG. 4 shows an isoluminance surface Sa that is a set of points at a distance of radius Ra from the light sources 8, 8,.

  Next, of the light emitted from the light sources 8, 8,..., The light reflected by the reflecting surface 9c and incident on the diffusion plate is considered (see FIG. 5). Assuming that the light source (virtual light source) 8b, 8b,... Exists on the opposite side of the light source (real light source) 8, 8,. Consider an isoluminance surface Sb that is a set of points at a distance of radius Rb from 8b, 8b,. At this time, the distance La from the light sources 8, 8,... To the reflecting surface 9c and the distance Lb from the virtual light sources 8b, 8b,... To the reflecting surface 9c are the same, and the radius Rb = 2La (= La + Lb). ) + Ra.

  In this way, the isoluminance surface Sa and the isoluminance surface Sb are obtained. The distance from the light sources 8, 8,... To the isoluminance surface Sa and the light sources 8b, 8b,. Since the distances are greatly different, the luminance on the equiluminance surface Sa is higher than the luminance on the equiluminance surface Sb. Therefore, with respect to the luminance, the luminance on the isoluminous surface Sa is more dominant than the luminance on the isoluminous surface Sb, and in fact, the light from the light sources 8b, 8b,. Work in the direction of increasing. The luminance at an arbitrary point P when light is emitted from the light sources 8, 8,... Is the light emitted from the light sources 8, 8,. , 8,... Is calculated based on a sum total obtained by integrating the intensity distributions of light that is reflected from the reflecting surface 9c and incident on an arbitrary point P.

  When the isoluminance surface Sc relating to the light emitted from the light sources 8, 8,. . Therefore, by forming the diffusing plate 10 in a corrugated shape matching the isoluminance surface Sc, the luminance of each part in the diffusing plate 10 becomes uniform, and illumination unevenness when light is emitted from the light sources 8, 8,. Can be prevented.

  The diffusion plate is not limited to the shape as shown in FIG. 6. For example, in consideration of the isoluminance surface Sc, the diffusion plate 10 has an angular shape with a convex surface as shown in FIG. It is good also as the diffusion plate 10 'which has.

  The optical sheets 11, 11, and 11 are disposed between the diffusion plate 10 and the liquid crystal panel 7, and are disposed in a laminated state with a predetermined distance from the diffusion plate 10 (see FIGS. 2 and 3). . Therefore, the diffusing plate 10 and the optical sheet 11 positioned facing the diffusing plate 10 are in a non-contact state (see FIG. 3). The optical sheets 11, 11, and 11 have various functions, for example, a polarization function, a diffusion function, a brightness enhancement function, and the like.

  By providing a predetermined gap between the optical sheet 11 and the diffusing plate 10, it is difficult to visually recognize the shape of the diffusing plate 10 from the outside, and the optical sheet 11 and the diffusing plate 10 are opposed to each other through an air layer. For this reason, it is difficult for light to travel in an unnecessary direction, and it is difficult to cause inconveniences such as a decrease in light use efficiency.

  As described above, the surface light source device 6 is configured by disposing the lamp housing 9 and the optical sheets 11, 11, 11 holding the light sources 8, 8,. Is done. The lamp housing 9, the diffusing plate 10, the optical sheets 11, 11, and 11 and the liquid crystal panel 7 are held by, for example, a frame 14 arranged so as to surround them (see FIG. 3).

  As described above, in the image display device 1, the diffusion plate 10 has a plurality of recesses 12, 12,... And a plurality of protrusions 13, 13,. Each part formed in a shape having a thickness and opposed to each light source 8, 8,... Is formed as a concave curved surface 13a, 13a,.

  Therefore, since the concave curved surfaces 13a, 13a,... Are positioned facing the light sources 8, 8,..., The difference in luminance at each part of the diffuser plate 10 is reduced, and the occurrence of uneven illumination is prevented. Since the thickness of the diffusing plate 10 is substantially uniform, the luminance can be improved without reducing the light utilization efficiency.

  In addition, since the luminance in all parts of the inner surface 10a of the diffusion plate 10 is substantially uniform, it is possible to reliably prevent uneven illumination.

  Further, by setting the distance between the diffusion plate 10 and the light sources 8, 8,... To be substantially the same distance at each part of the diffusion plate 10, it is possible to prevent uneven illumination from occurring with a high probability.

  In addition, since the reflection surface 9c that reflects light emitted from the light sources 8, 8,... Is formed in a flat shape, the image display device 1 can be thinned.

  In the above, an example in which a cold cathode fluorescent lamp (CCFL) is used as a light source has been shown. However, the light source may be of other types, and for example, a light emitting diode (LED) is used as follows. It is also possible.

  In the following example using a light emitting diode as a light source, the only difference is that the arrangement of the light source and the shape of the diffusion plate are different from the example using the cold cathode fluorescent lamp described above. Only the portions that are different from the example described above will be described in detail, and the other portions will be denoted by the same reference numerals as the same portions in the above-described example, and description thereof will be omitted.

  The surface light source device 6A includes a lamp housing 9 to which light sources 8A, 8A,... Are attached, a diffusion plate 10A, and optical sheets 11, 11, and 11 (see FIGS. 8 and 9).

  As the light sources 8A, 8A,..., Light emitting diodes are used, and the light sources 8A, 8A,. The light sources 8A, 8A,... Attached to the lamp housing 9 are arranged at equal intervals vertically and horizontally.

  The diffusing plate 10A is formed in a uniform shape with thicknesses in which the recesses 12A, 12A,... And the protrusions 13A, 13A,. The inner surface 10b of the diffusing plate 10A, that is, the surface facing the light sources 8A, 8A,..., Has portions corresponding to the protrusions 13A, 13A,. , 12A,... Are projected surfaces 12b, 12b,.

  The diffusion plate 10A is attached so as to close the opening 9d of the lamp housing 9 so that the concave curved surfaces 13b, 13b,... Face the light sources 8A, 8A,.

  The light sources 8A, 8A,..., Which are light emitting diodes, are light sources having radiant flux density anisotropy in which the light intensity distribution is not uniform according to the emission direction.

  Therefore, after obtaining an isoluminance plane in consideration of the radiant flux density anisotropy, it is necessary to form the diffusion plate 10A having a shape corresponding to the isoluminance plane. By forming the diffusing plate 10A having a shape corresponding to such an equiluminance surface, it is possible to prevent uneven illumination when light is emitted from the light sources 8A, 8A,.

  Note that the diffusion plate 10A may also be a diffusion plate having an angular shape with convex surfaces that are similar in shape to the diffusion plate 10A, as with the diffusion plate 10 (see FIG. 7).

  When the light source 8A, 8A,... Is attached to the bottom surface portion 9a of the lamp housing 9, most of the light emitted from the light source 8A, 8A,. Since the light is incident, it is possible to design the shape and the like of the diffusing plate 10A with little consideration of the light reflected and incident on the diffusing plate 10A, and the design can be facilitated.

  In the above description, the liquid crystal panel 7 has been described as an example of the spatial light modulation element. However, the spatial light modulation element is not limited to the liquid crystal panel 7. It may be other than 7.

  Further, in order to prevent uneven illumination, as shown in FIG. 10, a material having a light shielding property or a material for reducing the transmittance is provided at a predetermined position on the inner surface or outer surface of the diffusion plate 10, 10 ′, 10A. It is also possible to use patterns 15, 15,... By dot printing or the like.

  The specific shapes and structures of the respective parts shown in the above-described best mode are merely examples of the implementation of the present invention, and the technical scope of the present invention is limited by these. It should not be interpreted in a general way.

2 to 10 show a best mode for carrying out the present invention, and this figure is a perspective view showing an image display device. FIG. It is a disassembled perspective view which shows the apparatus main body of an image display apparatus. It is sectional drawing which shows an apparatus main body. It is for demonstrating the method of forming the specific shape of a diffuser plate with FIG. 5, This figure is a conceptual diagram which shows the equiluminance surface about the light radiate | emitted from the light source and entered directly. It is a conceptual diagram which shows the isoluminance surface about the light radiate | emitted from a light source, reflected, and incident. It is a conceptual diagram which shows an example of an equiluminance surface with a diffusion plate. It is a conceptual diagram which shows another diffusion plate. FIG. 9 shows an example in which a light emitting diode is used as a light source together with FIG. 9, and this figure is an exploded perspective view showing the apparatus main body. It is sectional drawing which shows an apparatus main body. It is a rear view which shows the example which attached | subjected the pattern by printing. It is a disassembled perspective view which shows a part of example of the conventional image display apparatus. It is a conceptual diagram for demonstrating the cause of illumination nonuniformity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image display apparatus, 6 ... Surface light source device, 7 ... Liquid crystal panel (spatial light modulation element), 8 ... Light source, 8b ... Virtual light source, 9 ... Lamp housing, 9c ... Reflecting surface, 10 ... Diffusing plate, 10a ... Inner surface (Surface facing the light source), 11 ... optical sheet, 12 ... concave, 13 ... projection, 13a ... concave curved surface, 10 '... diffuser plate, 6A ... surface light source device, 8A ... light source, 10A ... diffuser plate, 10b ... inner surface (Surface facing the light source), 12A ... concave portion, 13A ... projection, 13b ... concave curved surface

Claims (6)

A plurality of light sources arranged and held in a lamp housing;
A diffusing plate that is disposed facing the light source and diffuses the light emitted from the light source;
An optical sheet disposed on the opposite side of the light source across the diffusion plate,
The diffusion plate is formed in a shape having a plurality of concave portions and a plurality of protrusions alternately and having a substantially uniform thickness, and each portion facing the light source among the surfaces facing the light source of the diffusion plate is a concave curved surface. the way,
Using a light source having no radiant flux density anisotropy as the light source,
The distance between each part of the surface of the diffuser plate facing the light source and the light source located closest to each part is approximately the same distance,
A reflecting surface formed in a planar shape for reflecting light emitted from the light source toward the diffusion plate is provided at a position facing the diffusion plate, and each part of the surface of the diffusion plate facing the light source and the position closest to each part The distance between the light source and the imaginary light source on the opposite side across the reflective surface
A surface light source device characterized in that the luminance of all parts of the surface of the diffusion plate facing the light source is substantially uniform . The surface light source device according to claim 1, wherein a gap is formed between the optical sheet and the diffusion plate. Forming a reflective surface for reflecting light emitted from a plurality of light sources in the housing;
The surface light source device according to claim 1, wherein the plurality of light sources are attached to a reflection surface. A plurality of light sources arranged and held in a lamp housing;
A diffusing plate that is disposed facing the light source and diffuses the light emitted from the light source;
An optical sheet disposed on the opposite side of the light source across the diffusion plate;
A spatial light modulator disposed on the opposite side of the optical sheet with a diffusion plate in between,
The diffuser plate is formed in a shape in which a plurality of concave portions and a plurality of protrusions are alternately continuous and have a substantially uniform thickness, and each portion facing the light source among the surfaces facing the light source of the diffuser plate has a concave curved surface. the way,
Using a light source having no radiant flux density anisotropy as the light source,
The distance between each part of the surface of the diffuser plate facing the light source and the light source located closest to each part is substantially the same distance,
A reflecting surface formed in a planar shape for reflecting light emitted from the light source toward the diffusion plate is provided at a position facing the diffusion plate, and each part of the surface of the diffusion plate facing the light source and the position closest to each part The distance between the light source and the imaginary light source on the opposite side across the reflective surface
An image display device characterized in that the luminance of all parts of the surface of the diffusion plate facing the light source is substantially uniform . The image display device according to claim 4 , wherein a gap is formed between the optical sheet and the diffusion plate. Forming a reflective surface for reflecting light emitted from a plurality of light sources in the housing;
The image display device according to claim 4 , wherein the plurality of light sources are attached to a reflection surface.

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