JP2002277864A - Display device and illuminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device which displays image of high quality with less luminance change in a range of wide visual angle. SOLUTION: A display device 100 is provided with an illuminating unit 110, which emits light having luminance unevenness according to an exit angle, a display element 130 which modulates light from the illuminating unit, a first light diffusing means 120 arranged between the illuminating unit and the display element, and a second light diffusing means 140 arranged on the side opposite to the first light diffusing means of the display element. The first light diffusing means 120 diffuses light, so that light luminance unevenness on a first face S1 perpendicular to the light exit face of the illuminating unit is reduced to a greater extent than that on the other faces, and the second light diffusing means 140 diffuses light so that light luminance unevenness on a second face S2, which is perpendicular to the light exit face of the illuminating unit and crosses the first face is reduced to a greater extent than that on the other faces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device having good viewing angle characteristics and an illuminating device used for the same, and more particularly, to an illuminating device that emits light having a bias in luminance according to an outgoing angle, a light diffusing unit, The present invention relates to a liquid crystal display device that realizes a wide viewing angle by utilizing the same.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used in OA equipment, in-vehicle televisions, video camera monitors, etc. because of their characteristics of being lightweight, thin, and low power consumption. In a liquid crystal display device, unlike a display device such as a CRT, a PDP (plasma display panel), or an EL (electroluminescence), the display element itself does not emit light. For this reason, in a transmissive liquid crystal display device, a planar illumination device called a backlight is provided on the back of the liquid crystal display device, and the liquid crystal display device controls the amount of transmitted illumination light from the backlight for each pixel. By doing so, an image is displayed.

As a liquid crystal display device (hereinafter, referred to as an LCD), a device using a twisted nematic (TN) type and a super twisted nematic (STN) type liquid crystal display element is known. These liquid crystal display elements include a liquid crystal layer in which liquid crystal molecules are twisted (twisted) between a pair of substrates, and a pair of polarizing plates disposed behind and in front of the liquid crystal layer with the liquid crystal layer interposed therebetween. . Of the illumination light from the backlight, the light (polarized light) transmitted through the rear polarizer and incident on the liquid crystal layer rotates in the polarization direction according to the alignment state of the liquid crystal molecules. The front polarizing plate functions to selectively transmit only light having a predetermined polarization direction. Therefore, if the alignment state of the liquid crystal molecules is controlled,
The amount of light transmitted through the front polarizing plate can be controlled.

However, in the LCD using the TN type or STN type liquid crystal display element, the image quality greatly changes depending on the angle at which the image is viewed (viewing angle). For example, the contrast greatly changes, and the brightness and color tone of the halftone change. Therefore, a normal image cannot be obtained.

[0005] The viewing angle dependence of the image quality differs depending on the direction (azimuth) in which the image is viewed. For example, when a halftone display is performed as shown in FIG. 21, the liquid crystal molecules LC1 at the center of the liquid crystal layer are tilted with respect to the substrate surface (the liquid crystal molecules LC1).
In the case of (2), the polarized light C incident on the substrate from a predetermined oblique direction on the surface S4 where the rotation operation (or the rising operation) of the liquid crystal molecules occurs occurs within the plane of S4. ) Is strongly influenced by the angle dependence of the birefringence of the liquid crystal molecules. For this reason, the change in the amount of light according to the viewing angle increases.

On the other hand, polarized light A in the front direction and polarized light B incident obliquely in a plane S3 perpendicular to the plane S4.
Always passes through the liquid crystal layer so as to cross the long axis of the liquid crystal molecules, and thus is weakly affected by the angle dependence of the birefringence of the liquid crystal molecules. For this reason, a change in the amount of light according to the viewing angle is reduced.

Therefore, when the observer observes the polarized lights A and B, the observer can stably observe the halftone display corresponding to the alignment state of the liquid crystal molecules. In addition, there is a problem that the display of the half tone similar to that when the polarized lights A and B are observed is not performed, and the inversion between the bright display and the dark display easily occurs.

On the other hand, in order to reduce the viewing angle dependency as described above and achieve a wide viewing angle, the directivity (parallelism) of the illumination light emitted from the illumination device is increased,
LCD with light diffusion means arranged in front of liquid crystal display element
(For example, described in JP-A-7-239467). In such an LCD, an image having a desired contrast, halftone, and color obtained by reducing the luminance of illumination light having a large incident angle incident on the liquid crystal display element is diffused using light diffusion means. This achieves a wide viewing angle.

Hereinafter, with reference to FIG.
A conventional image display device described in JP-A-239467 will be described. As shown in FIG. 13, a conventional image display device 400
Includes a lighting device 410 having a surface light source 411 and a prism film 414, a liquid crystal display element 430, and a wave lens film 440.

In the image display device 400, the prism film 414 has a surface on which the prism is formed,
1 is arranged on the side not opposed to 1 and refracts and reflects light, so that the emission angle characteristic of high directivity can be obtained in a direction defined by a direction x orthogonal to the direction y in which the ridgeline 414a of the prism extends on the light emission surface. To be expressed. That is, the illumination device 410 emits illumination light having improved parallelism as shown by an arrow U in the drawing on a surface parallel to the direction x among surfaces perpendicular to the light emission surface.

In the present specification, a plane perpendicular to the light exit plane of the illumination device as described above is referred to as a “vertical plane”. For example, as shown in FIG. 22, when the light LT having the azimuth angle φ and the emission angle θ is emitted from the light emission surface S _xy (xy plane), the light LT is referred to as “a vertical plane parallel to the direction Dφ (or (A vertical plane extending in the direction Dφ) ”. The direction D Ø are the direction defined by the azimuth angle φ in the plane S _xy, sometimes referred to as orientation D Ø. The “light emitting surface” refers to a virtual surface formed by regarding the entire surface from which light is emitted as a plane, even if the surface has irregularities due to the provision of a prism or the like. means.

The liquid crystal display element 430 displays an image by controlling the transmittance of the light emitted from the illumination device 410 for each pixel. However, since light with improved parallelism is incident, a desired contrast is obtained. , An image having a halftone and a color tone can be displayed. However, the liquid crystal display element 43
The display light emitted from 0 has high directivity emission angle characteristics on a vertical plane parallel to a direction x orthogonal to the ridge line 414a of the prism formed on the prism film 414. On the other hand, a wave lens film 440 is provided, and the direction in which the ridge line 414a of the prism extends and the direction 440a in which the ridge line of the wave lens extends substantially coincide with each other. Wave lens film 44
0 is a direction x orthogonal to the ridge line 440a of the wave lens.
Since it has the function of diffusing light in a vertical plane parallel to, the display light that has passed through the liquid crystal display element 430 is diffused so that its emission angle characteristics are reduced. Thus, the display device 400 displays an image having a desired display quality in a wide viewing angle range.

As shown in FIG. 14, an image display device 500 described in Japanese Patent Application Laid-Open No. Hei 8-304631 has a lighting device 510 comprising a light source 511, a light reflection sheet 512, a light guide 513, and a prism film 514. , Liquid crystal display element 530, lenticular lens film 54
0.

In the image display device 500, the prism film 514 is disposed so that the prism-forming surface faces the light guide 513, and the prism film 514 extends perpendicularly to the ridge line of the prism by refraction or reflection of the light by the prism. The liquid crystal display element 530 is irradiated with light having high directivity and emission angle characteristics with improved parallelism on the surface. The light transmitted through the liquid crystal display element 530 is the lenticular lens film 5
Due to 40, the light is diffused in a vertical plane perpendicular to the ridge line of the lenticular lens. As described above, the image display device 500 also displays an image having a desired display quality in a wide viewing angle range by substantially matching the direction of the ridge of the prism with the direction of the ridge of the lenticular lens.

Japanese Patent Application Laid-Open No. 2-118518 discloses a light source 611, a spherical mirror 612,
An image display device 600 including a lighting device 610 having a lens 614, a liquid crystal display element 630, and a light diffusing unit 640 is described.

In the image display device 600, the light source 611
Is refracted by the lens 614, so that the liquid crystal display element 630 is irradiated with light having improved parallelism on a vertical plane parallel to a direction x perpendicular to the direction y in which the lens 614 extends. Light that has passed through the liquid crystal display element 630 is diffused by the light diffusion means 640. This light diffusion means 64
Numeral 0 is composed of, for example, a wave lens film and functions to diffuse light on a vertical plane parallel to the direction x. Thus, the image display device 600 displays an image having a desired display quality in a wide viewing angle range. The lens 614
Can be a Fresnel lens.

[0017]

However, in the above-mentioned conventional image display device, a phenomenon has occurred in which the brightness of the display light decreases as the viewing angle increases in a specific direction on the image display surface. . Hereinafter, the reason will be described.

FIG. 16 shows a prism film 414 provided in the illumination device 410 of the image display device 400 (see FIG. 13) described in the above-mentioned Japanese Patent Application Laid-Open No. 7-239467. As described above, the illumination light from the surface light source 411 is efficiently refracted and reflected on a plane that is perpendicular to the light exit surface of the prism film 414 and extends in a direction perpendicular to the ridge line of the prism, and has high directivity. Is emitted.

On the other hand, the illumination light from the surface light source 411 is more likely to be reflected on a plane formed at a small angle with the light exit surface of the prism film 414 than on the plane, and the amount of light transmitted through the prism film 414 is reduced. this is,
This is because the apparent angle of the prism film 414 with respect to the illumination light increases, and the illumination light having a large incident angle on the light exit surface of the prism film 414 is easily reflected on the surface. Note that, in a plane formed by an angle smaller than the plane with the prism film 414 and larger than the plane, the amount of transmitted light is smaller than in the plane, and the amount of transmitted light is larger than in the plane.

As a result, even on a vertical surface extending in the direction of the ridge line of the prism (that is, a surface perpendicular to the light exit surface of the prism film 414 and parallel to the ridge line direction y of the prism), the emission angle is also large. As the size increases, the amount of emitted light decreases. As a result, even on a vertical surface extending in the ridge direction of the prism, the emitted light has a bias in luminance according to the emission angle.

As a specific example, FIGS. 17A and 17B show emission angle characteristics when "BEF (trade name)" manufactured by Sumitomo 3M Limited is arranged as the prism film 412 in the illumination device 410. FIG. . As shown in FIGS. 17A and 17B, it can be seen that the illuminating light has high directivity both on a vertical surface extending in a direction perpendicular to the ridge line of the prism and on a vertical surface extending in a direction parallel thereto. That is,
In any of these perpendicular surfaces orthogonal to each other, the brightness of the light emitted from the prism film 414 is biased according to the emission angle.

On the other hand, the wave lens film 440 is arranged such that the ridge of the wave lens is arranged in parallel with the ridge of the prism of the prism film 414, and diffuses light in a vertical plane extending in a direction perpendicular to the ridge, but diffuses the light in a vertical plane spreading in the ridge. Does not substantially diffuse light. Accordingly, the wave lens film 440 modulated by the liquid crystal display element 430 is used.
Has a desired contrast, halftone, and color tone, and in an azimuth perpendicular to the ridgeline of the wave lens, there is little change in the luminance of the display light according to the viewing angle, and the observer views the image well. However, in an azimuth parallel to the ridge line, as the viewing angle increases, the brightness of the display light decreases, and visual observation becomes difficult.

Also, Japanese Patent Application Laid-Open No. 7-239467 describes that the front surface (observer side surface) of a liquid crystal display element is
There is also disclosed an image display device in which two wave lens films are arranged such that the ridges of each wave lens are orthogonal to each other. In this case, the image displayed by the liquid crystal display device is diffused by two wave lens films in two perpendicular planes orthogonal to each other, so that the image can be observed at a constant luminance from any direction. . However, in this configuration, light from the surroundings is reflected and scattered by the two wave lens films, adversely affecting the image displayed on the liquid crystal display element, and significantly deteriorating the display quality of the image. Problems arise.

In the illumination device 510 of the image display device 500 disclosed in Japanese Patent Application Laid-Open No. Hei 8-304631, the output light is also high on a vertical surface that extends in a direction perpendicular to the ridge line of the prism due to the refraction and reflection of the prism of the prism film 514. The emission angle characteristic of the directivity is generated, and the light amount decreases as the emission angle increases even on a vertical surface extending in a direction parallel to the ridge line.

More specifically, FIG. 18 shows the emission angle characteristics of illumination light when "Diaart S165 (trade name)" manufactured by Mitsubishi Rayon Co., Ltd. is used for the prism film 514.
(A) and (b). FIG. 18 (a) and (b)
As can be seen from the figure, outgoing light has a very high directivity on a vertical surface extending in a direction orthogonal to the ridge line of the prism, and also has a high directivity on a vertical surface extending in a direction parallel to the ridge line. .

The image displayed after receiving the illumination light from the illumination device 510 and passing through the liquid crystal display element 530 is diffused by the lenticular lens film 540 in the direction orthogonal to the ridge line of the lenticular lens. Is displayed in a wide viewing angle range. However, in an azimuth parallel to the ridgeline of the lenticular lens, the luminance of the display light greatly changes according to the viewing angle, and it is difficult to observe an image if the viewing angle is large.

Also in the illumination device 610 of the image display device 600 disclosed in Japanese Patent Application Laid-Open No. 2-118518, the emission angle characteristic of the illumination light has a very high directivity in a direction orthogonal to the ridge of the lens 614 and is parallel to the ridge. Directivity is provided in various directions.

The emission angle characteristics of the emitted light on the vertical surface extending in the ridge direction are different between the central portion where the thickness of the lens 614 is maximum and the end portion where the thickness of the lens 614 is minimum. This is because, as shown in FIG. 19, the inclination of the lens surface with respect to the horizontal plane PH is small at the center of the lens 614, and the illumination light easily passes through the lens 614, but the inclination of the lens surface increases as approaching the end P2 of the lens. This is because the incident angle of light on the lens surface increases, and the amount of illumination light decreases. FIGS. 20A and 20B show the emission angle characteristics of the illumination light after passing through the lens 614.
Shown in As shown in FIG. 20B, in the direction parallel to the ridge line of the lens, light having higher directivity is emitted at the end of the lens 614 than at the center.

An image formed by modulating the illumination light from the illumination device 610 with the liquid crystal display element 630 is diffused in one direction by light diffusion means 640 such as a wave lens film or a lenticular lens film to obtain a desired display quality. However, in an azimuth orthogonal to this azimuth, a change in luminance of the display light according to the viewing angle is large, and when the viewing angle is large, the luminance is significantly reduced. In addition, a change in luminance is observed differently between the center and the end of the lens. For this reason, when observing an image, a difference in the rate of decrease in luminance according to the viewing angle occurs between the center and the end of the screen, and an image having different luminance according to a position on the screen is observed.

As described above, in the conventional image display device, it is possible to modulate incident light to a desired state by making high directivity light incident on the liquid crystal display element. It has been difficult to properly observe emitted light (display light) in a wide viewing angle range in any direction.

The present invention has been made in order to solve the above-mentioned problem, and an object of the present invention is to provide a display device capable of displaying an image having a desired display quality in a wide viewing angle range in any direction. Aim.

Another object of the present invention is to provide a spread illuminating device suitably used in the above display device.

[0033]

According to the present invention, there is provided a display device, comprising: an illuminating device for emitting highly directional light having a bias in luminance according to an emission angle; and a light modulator for modulating light emitted from the illuminating device. A display element, a first light diffusing means disposed between the lighting device and the display element, and a first light diffusing means disposed on a side of the display element opposite to a side on which the first light diffusing means is disposed. A second light diffusing means, wherein the first light diffusing means has a first light diffusing means perpendicular to a light exit surface of the lighting device.
In the surface, the light is diffused so as to reduce the deviation of the luminance of the light than in the other surface, the second light diffusing means is perpendicular to the light emitting surface of the lighting device,
Further, the light is diffused on the second surface intersecting the first surface so as to reduce the unevenness of the luminance of the light as compared with the other surfaces.

[0034] In a preferred embodiment, the first surface and the second surface are substantially perpendicular to each other.

[0035] In a preferred embodiment, the first light diffusing means does not substantially reduce the deviation of the luminance of the light on the second surface.

[0036] In a preferred embodiment, the second light diffusing means does not substantially reduce the deviation of the luminance of the light on the first surface.

[0037] In a preferred embodiment, the light modulation angle of the display element on the first surface is wider than the light modulation angle on the second surface.

[0038] In a preferred embodiment, the display element includes a liquid crystal layer formed of a plurality of liquid crystal molecules that can assume a twisted arrangement state in a thickness direction, and a pair of polarizers sandwiching the liquid crystal layer.

In a preferred embodiment, the liquid crystal molecules located at the center in the thickness direction of the liquid crystal layer move in the second plane by applying a voltage.

[0040] In a preferred embodiment, the first diffusing means is formed of a light transmissive material, and refracts light transmitted through the first diffusing means at a light exit surface of the first diffusing means. Or it can be reflected.

In a preferred embodiment, the first diffusing means has a plurality of lenses extending parallel to each other.

[0042] In a preferred embodiment, the plurality of lenses extend along a first direction defined by a direction in which the first surface extends in an emission surface of the lighting device.

In a preferred embodiment, the first light diffusing means diffuses only light in a specific incident angle range on the second surface.

The illumination device according to the present invention is a planar illumination device that emits light having a bias in luminance according to an emission angle, and emits light on a first surface perpendicular to a light emission surface of the illumination device. In addition to having a luminance deviation depending on the angle, the second surface perpendicular to the light exit surface of the illumination device and intersecting with the first surface is more dependent on the exit angle than on the first surface. Light with reduced luminance bias is emitted.

In a preferred embodiment, the lighting device comprises:
In the second surface, light is diffused so as to reduce the unevenness in luminance of light as compared with other surfaces, and the first surface is diffused.
In the aspect, there is provided a light diffusing unit that does not substantially reduce the deviation of the luminance of the light.

Further, the display device of the present invention comprises the above-mentioned spread illuminating device, a display element capable of modulating light emitted from the spread illuminating device, and a light diffusing light transmitted through the display device. Diffusing means, wherein the light diffusing means diffuses the light on the first surface so as to reduce the unevenness of the luminance of the light as compared with the other surface.

The operation of the present invention will be described below.

In the image display device of the present invention, the highly directional light emitted from the illumination device is diffused in the first vertical plane by the first diffusing means, and then is incident on the display element. An image is displayed by diffusing the light modulated into the state in the second vertical plane by the second diffusing means. With this configuration, the display light is diffused on both the first vertical plane and the second vertical plane that intersect each other, so that the luminance according to the viewing angle is obtained even when the display light is observed from any direction. And a relatively bright image can be observed. In the present invention, the first and second diffusion means are not provided on the emission side surface of the display element, but are arranged so as to sandwich the display element. Does not occur to lower the image quality. Further, the light incident on the display element is diffused in the first vertical plane by the first diffusion means, but if this diffusion direction is appropriately selected, the diffused light can be transmitted to the display element at a desired level. Therefore, it is possible to realize a wide viewing angle without deteriorating the quality of an image.

In this specification, the term "light modulation angle of the display element" means that when the light is incident on the display element at various angles, the display element converts the incident light into a desired state (that is, in the front direction). In contrast to the display when the light is modulated, a bright display and a dark display are not reversed, and a similar image can be displayed). For example, in the case of a TN type or STN type display element, particularly in the case of performing a halftone display, there are certain factors such as the twist of the liquid crystal molecules (the direction of the helix, the start position of the helix of the liquid crystal molecules) and the refractive index anisotropy of the liquid crystal molecules. Light incident at an angle of incidence greater than the angle is not modulated to the desired state. In this specification, when light is not modulated to a desired state even at a relatively small incident angle on a surface substantially perpendicular to the incident surface of the display element, the light modulation angle is said to be narrow, and is relatively large. When light is modulated to a desired state even at an incident angle, the light modulation angle is said to be wide. Note that the term “light modulation” includes light amplitude modulation, light phase modulation, light deflection, and the like, and broadly means an optical function capable of controlling the magnitude of the luminance of emitted light.

[0050]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 shows an image display device (liquid crystal display device) 100 according to Embodiment 1. The image display device 100 includes an illuminating device 110 that emits highly directional light having a bias in luminance according to an emission angle, a first light diffusing unit 120 that diffuses light in a predetermined plane, The liquid crystal display device 130 includes a liquid crystal display element 130 that can modulate a desired state for each pixel, and a second light diffusion unit 140 that diffuses light in a predetermined plane. The liquid crystal display element 130
It is sandwiched between the first light diffusion means 120 and the second light diffusion means 140.

In this embodiment, a conventional TN type liquid crystal display element is used as the liquid crystal display element 130. That is, the liquid crystal display element 130 includes a liquid crystal layer formed of a plurality of liquid crystal molecules that can assume a twisted alignment state in the thickness direction, and a pair of polarizing plates disposed so as to sandwich the liquid crystal layer. I have. In the liquid crystal display element 130, by controlling the voltage applied to the liquid crystal layer for each pixel, the light transmittance of the pixel region is changed, whereby a desired image can be displayed.

The lighting device 110 includes a plurality of light sources 111,
It comprises a light reflection sheet 112, a light diffusion plate 113, and directivity control means 114. As the directivity control unit 114 of the illumination device 110, for example, a prism film “BEF” manufactured by Sumitomo 3M Limited can be used. The low directivity light having low luminance angle dependency is emitted from the plurality of light sources 111, and the directivity is given by the directivity control unit 114 to the illumination light.

The first light diffusing means 120 and the second
As the light diffusing means 140, for example, a known lenticular lens sheet (for example, a UCS sheet manufactured by Dai Nippon Printing Co., Ltd.) can be used. A lenticular lens film that is thinner than a lenticular lens sheet and can be formed integrally with another optical member may be used. Note that the ridge direction of the second light diffusion means (second lenticular lens film or sheet) 140 and the ridge direction of the prism film (directivity control means) 114 are arranged substantially in parallel, and the first light diffusion means ( The ridge direction of the first lenticular lens film or sheet (120) is arranged orthogonal to these. Here, as illustrated, the direction in which the ridge line of the first lenticular lens film 120 extends is defined as the x direction, and the direction in which the ridge line of the lenticular lens of the second lenticular lens film 140 (and the prism of the prism film 114) extends (x The direction perpendicular to the direction) is defined as the y direction. A direction orthogonal to these directions x and y is defined as a z direction. In the present embodiment, the x direction and the y direction are orthogonal.

FIGS. 2A and 2B show the lighting device 11.
Of the illumination light emitted from the illumination device 11 and the illumination device 11
FIG. 9 shows the emission angle characteristics of light after the illumination light from 0 is diffused by the first lenticular lens film 120. FIG. FIG. 2A shows the light exit surface (xy) of the prism film 114.
The exit angle characteristic on a vertical plane (xz plane) extending in a direction x perpendicular to the ridge line of the prism of the prism film 114 among the planes perpendicular to the plane (plane) is shown. FIG. 2B shows emission angle characteristics on a vertical plane (yz plane) extending in a direction y parallel to the ridge line of the prism.

As shown in FIG. 2A, the lighting device 110
Has high directivity emission angle characteristics on a vertical plane (xz plane or second plane) spread in the x direction by the action of the prism film 114 provided as a directivity control unit. Here, as the luminance,
The relative luminance when the luminance in the front direction is 1 is shown. In addition, as described above, light having a large incident angle is easily reflected on the surface of the prism film 114.
As shown in (1), the illumination light from the illumination device 110 has directivity also on a vertical plane (yz plane or first plane) extending in the y direction.

On the other hand, the light emitted from the first lenticular lens film 120 has reduced directivity on the yz plane, as shown in FIG. 2B. This is because the first lenticular lens film 120 has an effect of diffusing light on a vertical plane (yz plane) extending in a direction y perpendicular to the ridge line of the lenticular lens so as to reduce a deviation in luminance according to the emission angle. Because it has. Also, the first lenticular lens film 120
Does not practically diffuse light on a vertical plane (xz plane) that spreads in a direction parallel to the ridge line, so that the emitted light has high directivity on this vertical plane as shown in FIG. As a result, the first lenticular lens film 1
The illumination light emitted from 20 has an emission angle characteristic of high directivity in the xz plane, but has an emission angle characteristic in which the luminance changes slowly in the yz plane.

FIG. 3 is a diagram schematically showing a change in directivity of light passing through the liquid crystal display device 100. As shown in the drawing, the emitted light from the illumination device 110 has high directivity on both the vertical plane (second plane) S2 extending in the x direction and the vertical plane (first plane) S1 extending in the y direction. Have. Further, the first lenticular lens film 120 diffuses the illumination light so as to reduce the unevenness of the luminance on the first surface S1. At this time, the illumination light is not diffused on the second surface S2. As a result, light having relatively high parallelism on the second surface S2 and relatively low parallelism on the first surface S1 is irradiated from the first lenticular lens film 120 to the liquid crystal display element 130. .

The liquid crystal display element 130 displays an image by controlling the transmittance of incident light for each pixel. However, since the liquid crystal display element 130 of the present embodiment is a TN-type liquid crystal display element, as shown in FIG.
The effect of light modulation also differs depending on the light incident direction (azimuth). Hereinafter, the liquid crystal display element 130 will be described with reference to FIG.
A description will be given of the light modulation action in the first embodiment.

Normally, the liquid crystal display device is set so as to display a desired image in the front direction, so that the polarization A of the liquid crystal molecules from the front direction of the liquid crystal display element is modulated to a desired state. The orientation state is controlled. In this state, the liquid crystal molecules L located at the center in the thickness direction of the liquid crystal layer are
Polarized light B incident obliquely in a plane S3 perpendicular to the plane S4 where C1 rises is modulated similarly to the polarized light A even when the incident angle is relatively large. Accordingly, an incident angle range in which the liquid crystal display element can perform light modulation on the surface S3 to a desired state (referred to as a light modulation angle in this specification).
Is wide.

On the other hand, the polarized light C that is obliquely incident on the plane S4 where the liquid crystal molecules LC1 rise in the center of the liquid crystal layer in the thickness direction, even if the incident angle is relatively small,
It is easy to be modulated to a state different from the polarization A. For example, polarization A
In this case, the rotation in the polarization direction is higher when passing through the liquid crystal molecules LC1 in the lying state than when passing through the liquid crystal molecules LC2 in the inclined state in the plane S4. When passing through the liquid crystal molecules LC1 in the tilted state,
The rotation of the polarization direction is lower than when the liquid crystal molecules LC2 pass through the liquid crystal molecules LC2 inclined in the plane S4. As a result, a pixel region that looks bright in the direction of polarized light A (front direction) looks dark in the direction of polarized light C, and conversely, a pixel region that looks dark in the direction of polarized light A looks bright in the direction of polarized light C. Can occur.

Since such a phenomenon occurs, the incident angle range in which the liquid crystal display element can modulate incident light on the surface S4 to a desired state is narrowed. Therefore, in the liquid crystal display device of the present embodiment, the light modulation angle on the surface S4 where the liquid crystal molecules LC1 located at the center in the thickness direction of the liquid crystal layer rises is smaller than the light modulation angle on the surface S3 perpendicular to the surface S4.

Referring back to FIG. As mentioned above, the first
The light emitted from the lenticular lens film 120 has high directivity emission angle characteristics on the second surface S2 parallel to the ridgeline direction of the lenticular lens. In the liquid crystal display element 130 of the present embodiment, the liquid crystal molecules L located at the center in the thickness direction of the liquid crystal layer on the second surface S2
C1 is arranged to rise. That is, the surface S4 of the liquid crystal display element 130 where the light modulation angle is narrow,
The surface S2 of the lenticular lens film 120 that emits highly directional light is arranged in parallel.

In this way, light having high directivity emission angle characteristics is incident on the liquid crystal display element 130 on the second surface S2, so that the light is modulated in an undesired state in the liquid crystal display element 130. Is prevented. Although the directivity of the incident light is reduced on the first surface S1, the light modulation angle of the liquid crystal display element 130 on this surface S1 is relatively wide, so that the light can be appropriately modulated. Therefore, it is possible to display an image having a desired contrast, halftone, and color tone.

However, since the light (display light) modulated by the liquid crystal display element 130 has high directivity on the second surface S2, the azimuthal direction of this surface (ie, x
Direction), the change in luminance of the display light according to the viewing angle is large. On the other hand, the second lenticular lens film 140 diffuses the display light on the second surface S2, and eliminates a change in luminance of the display light according to the viewing angle. Thereby, it is possible to display an image having desired display quality and brightness in a wide viewing angle range in any direction. Further, in the liquid crystal display device 100 of the present embodiment, since a plurality of diffusing units are not provided in front of the liquid crystal display element 130, ambient light is not reflected and the display quality is not degraded. The first lenticular lens film 1
Since the display light is diffused on the first surface S1 by the diffusion action of 20, the second lenticular lens film 140 need not substantially diffuse the light on the first surface S1.

FIGS. 4A and 4B show a change in luminance of display light according to a viewing angle in the image display device 100 of the present embodiment, and a conventional image display without the first lenticular lens film 120. 7 shows a comparison with a change in luminance of display light according to a viewing angle in the device. As can be seen from FIGS. 4A and 4B, in the image display device 100 of the present embodiment, the first lenticular lens film 1
Although the brightness of the display light in the front direction is lower than that of the conventional device due to the provision of 20, a good image with little change in the brightness of the display light according to the viewing angle is displayed in any direction. I understand.

In the image display device of the present embodiment, the direction of the ridge line of the prism film which is the directivity control means provided in the illumination device 110 may be arranged in a direction different from that of the present embodiment. This is because, as described above, the illumination light that has passed through the prism film has a high directivity emission angle characteristic on a surface extending in a direction orthogonal to the ridge line of the prism and on a surface extending in a direction parallel thereto.

As the illuminating device, any device having various configurations can be used as long as it can emit illuminating light having a highly directional emission angle characteristic. As the directivity control unit of the lighting device, a lens, a Fresnel lens, or the like can be used in addition to the prism film.

The first light diffusing means has a function of diffusing light so as to reduce the deviation of luminance (ie, directivity) on a predetermined vertical plane (or azimuth) as compared with other vertical planes. If so, various forms can be used. A wave lens film or the like may be used as the first light diffusing means. Also, the first
The light diffusing means may have a function of diffusing light having a large incident angle without diffusing light having a small incident angle on the predetermined vertical plane.

Similarly to the first light diffusing means, the second light diffusing means has a function of diffusing light so as to reduce the deviation of luminance on a predetermined vertical surface (on other vertical surfaces). If so, various forms can be used.

In order to make effective use of the illumination light, polarization selective reflection is preferably performed between the liquid crystal display element 130 and the illumination device 110 (preferably, between the liquid crystal display element 130 and the first diffusion means 120). Means may be provided. As the polarization selective reflection means, "DBEF" manufactured by Sumitomo 3M Limited, or the like can be used. The polarization selective reflection means is an optical means having a function of transmitting polarized light incident on the liquid crystal display element 110 in a predetermined direction, while reflecting polarized light in a direction orthogonal to the predetermined direction. The reflected light is reflected again in the illumination device, and after changing the polarization direction, travels to the polarization selective reflection means. Therefore, the amount of light incident on the liquid crystal display device can be increased.

(Embodiment 2) FIG. 5 shows an image display device 200 of Embodiment 2. The image display device 200 includes a lighting device 210, a first light diffusing unit 220, a liquid crystal display element 230, and a second light diffusing unit 240.

The difference between the image display device 200 according to the second embodiment and the image display device 100 according to the first embodiment is the configuration of the illumination device. The lighting device 210 according to the second embodiment includes a light source 211,
The light reflecting sheet 212, the light guide 213, and the directivity control unit 214 are provided. The illumination device 210 is an edge light type illumination device, and emits light from a light source 211 formed of a fluorescent tube or the like toward the liquid crystal display element 230 by a light guide 213. Light reflection sheet 212
Functions to reflect light from the light source 211 to improve light use efficiency. In addition, the lighting device 210
As the directivity control means 214, a prism film "Diaart S165" manufactured by Mitsubishi Rayon Co., Ltd. is used.

As the first light diffusing means 220 and the second light diffusing means 240, lenticular lens films are used as in the first embodiment. Also, as in the first embodiment,
The direction of the ridge line of the directivity control means (prism film) 214 and the direction of the ridge line of the second lenticular lens film (second light diffusing means) 240 are substantially parallel (y direction), and the first lenticular lens film The (first light diffusing means) 220 is arranged such that the ridge direction (x direction) of the 220 is orthogonal to these.

FIGS. 6A and 6B show the lighting device 21.
0 and the emission angle characteristics of the illumination light emitted from the illumination device 21
FIG. 9 shows the emission angle characteristics of light after illumination light from 0 is diffused by the first lenticular lens film 220. FIG. FIG. 6A shows emission angle characteristics on a vertical plane (xz plane) extending in a direction orthogonal to the ridge line of the prism of the prism film 214. FIG. 6B shows emission angle characteristics on a vertical plane (yz plane) extending in a direction parallel to the ridge line of the prism.

As shown in FIGS. 6A and 6B, the illumination light from the illumination device 210 is
Has a very high directivity in the xz plane (second surface) parallel to the ridge line of the prism,
It also has high directivity on the yz plane (first surface) orthogonal to the ridge line of the prism.

On the other hand, the illumination light after passing through the first lenticular lens film 220 has a very high directivity in the xz plane as shown in FIG.
As shown in FIG. 6B, on the yz plane, there is almost no change in luminance according to the emission angle.

The liquid crystal display element 230 includes a lighting device 210
Then, the illumination light diffused in a predetermined direction by the first lenticular lens film 220 after the light is emitted is incident thereon, and the liquid crystal display element 230 controls the transmittance of the illumination light for each pixel to display an image. Also in the present embodiment, as in the first embodiment, the vertical surface (first surface) where the first lenticular lens film 220 diffuses light and the vertical surface of the liquid crystal display element 230 where the light modulation angle is relatively wide are different. The liquid crystal display element 230 is arranged so as to be positioned in parallel. Thereby, incident light can be modulated to a desired state.

The display light from the liquid crystal display element 230 is diffused on the second surface by the second lenticular lens film 240. This makes it possible to provide an image having a predetermined display quality in a wide viewing angle range and a small change in luminance according to the viewing angle in any orientation.

FIGS. 7A and 7B show a change in luminance of display light according to a viewing angle in the image display device 200 of the present embodiment and a conventional image display device in which the first lenticular lens film 220 is not provided. The luminance change of the display light depending on the viewing angle is compared and shown. As can be seen from FIGS. 7A and 7B, the image display device 2 of the present embodiment
00, the first lenticular lens film 220
Although the brightness in the front direction is reduced by providing,
It can be seen that a good image with little change in luminance of the display light according to the viewing angle is displayed in any direction.

In the image display device of the present invention,
Various types of illumination devices can be used as long as high-directional light can be emitted, and a prism film, a lens, a Fresnel lens, or the like can be appropriately used as the directivity control unit.

As the first diffusing means and the second diffusing means, various means can be used as long as they have a function of diffusing light in a predetermined direction so as to reduce the directivity in other directions. The form can be used.

Further, similarly to the first embodiment, the illumination light may be effectively used by providing a polarization selective reflection means on the back surface of the liquid crystal display element 230.

(Embodiment 3) FIG. 8 shows an image display device 300 of Embodiment 3. The image display device 300 includes a lighting device 310, a first light diffusing unit 320, a liquid crystal display element 330, and a second light diffusing unit 340.

The image display device 300 is different from the image display device 100 of the first embodiment in that the configuration of the illumination device and the first
This is the configuration of the light diffusion means. Hereinafter, the lighting device 310 and the first light diffusing unit 320 of the present embodiment will be described.

The lighting device 310 includes a plurality of light sources 311,
It is composed of a light reflection sheet 312 and directivity control means 314. In the present embodiment, a transparent base material having a plurality of Fresnel lenses formed on the surface is used as the directivity control unit 314 of the lighting device 310. Each of the plurality of Fresnel lenses corresponds to each of the plurality of light sources 311. The central portion 314c of each lens has a surface having a relatively small inclination with respect to the horizontal plane, and the end 314e has a relatively small inclination with respect to the horizontal plane. It has a large surface. Each light source 31
The light from No. 1 is refracted by each lens formed on the transparent substrate, and is irradiated with illumination light having high directivity and emission angle characteristics. The direction orthogonal to the ridge line of the Fresnel lens is defined as an x direction, and the direction parallel to the ridge line (the direction in which the Fresnel lens extends) is defined as the y direction.

Further, as the first light diffusing means 320,
An optical element having a function of diffusing only light in a predetermined incident angle range in a predetermined direction is used. Specifically, "Lumisty (trade name)" manufactured by Sumitomo Chemical Co., Ltd. is used. “Lumisty” does not diffuse light in the xz plane, and in the yz plane, for example, an incident angle of ± 20 °
Light in the range of ± 70 ° is selectively diffused. As described above, it is desirable that the diffusion angle range of the first light diffusion means 320 is selected so as to diffuse only light having a relatively large emission angle on the yz plane.

Further, as the second light diffusing means 340,
As in the first embodiment, a lenticular lens film is used. The lenticular lens film 340 is
The lenticular lens is arranged so that the ridge line is parallel to the y direction, and diffuses light in the xz plane.

FIGS. 10A and 10B show the lighting device 3.
10 shows the emission angle characteristics of the illumination light emitted from FIG. FIG.
As can be seen from (a) and (b), the lighting device 310
The emission angle characteristics of the illumination light emitted from the
Surface) has a very high directivity and y
It has high directivity also in the z plane (first plane). Further, in the yz plane, the end 314e is compared with the center 314c of the lens provided in the directivity control unit 314.
Emits light having higher directivity.

The illumination light after passing through the first light diffusion means “Lumisty” 320 has a very high directivity in the xz plane as shown in FIG. As shown in (b), the directivity is reduced in the yz plane.

As can be seen by comparing FIG. 9B and FIG. 10B, the light that has passed through the “Lumisty” 320 has more outgoing angle characteristics at the center and the end of the lens. Similar. As described above, by using the diffusing unit that diffuses only light having an incident angle in a specific range, the directivity in the yz plane can be reduced without significantly lowering the luminance of the illumination light in the front direction.

The liquid crystal display element 330 includes a lighting device 310
The illumination light emitted from the LCD and diffused in a predetermined direction by the “Lumisty” 320 enters the liquid crystal display element 33.
0 displays an image by controlling the transmittance of the illumination light for each pixel. Also in the present embodiment, as in the first embodiment, the first diffusing unit 320 diffuses light into a vertical plane (first plane).
And the liquid crystal display element 33 so that the vertical plane of the liquid crystal display element 330 having a relatively wide light modulation angle is positioned in parallel.
0 is arranged. Thereby, incident light can be modulated to a desired state.

The display light from the liquid crystal display element 330 is diffused on the second surface by the second diffusion means 340. This makes it possible to provide an image having a predetermined display quality in a wide viewing angle range and a small change in luminance according to the viewing angle in any orientation.

FIGS. 11A and 11B show a change in luminance of display light according to a viewing angle in the image display device 300 of this embodiment. FIGS. 12A and 12B show a change in luminance of display light according to a viewing angle in a conventional image display device in which the first light diffusion unit 320 is not provided.

As can be seen from FIG. 12B, in the conventional image display device, the luminance of the display light changes greatly depending on the viewing angle in the y direction, and the center and the end of the lens formed in the directivity control means 314. And have different luminance changes. As a result, for example, at a viewing angle of ± 70 °, the brightness of the display light at the end of the lens is less than half that of the center of the lens, and the brightness corresponding to the lens is observed.

On the other hand, as can be seen from FIG. 11 (b), in the image display device 300 of the present embodiment, the luminance change according to the viewing angle of the display light in the y direction is achieved by disposing the “Lumisty” 320. And the change in luminance is not significantly different between the center and the end of the lens. As a result, for example, at a viewing angle of ± 70 °, the luminance of the display light is substantially equal between the center and the end of the lens, and a good image can be displayed.

In the image display device of the present embodiment, the light reflecting sheet 312 in the lighting device 310 may have a spherical or curved shape depending on the light source 311. Further, the range of the incident angle of the light diffused by the “Lumisty” 320 used as the first light diffusing means is not limited to the angle range in the present embodiment, but may be determined by the emission angle characteristics of the illumination light from the illumination device 310. It can be set appropriately as needed.

Further, in the image display device of the present invention,
Various types of illumination devices can be used as long as high-directional light can be emitted, and a prism film, a lens, a Fresnel lens, or the like can be appropriately used as the directivity control unit. Further, the first diffusing means and the second diffusing means may have various forms as long as they have a function of diffusing light in a predetermined direction so as to reduce the directivity as compared with other directions. Can be used. Further, similarly to the first embodiment, the illumination light may be effectively used by providing a polarization selective reflection unit on the back surface of the liquid crystal display element 230.

Although the embodiment of the present invention has been described above, the display device of the present invention has high directivity on a first vertical plane perpendicular to the light emitting surface, and has a second directivity crossing the first plane.
May be configured using a planar illumination device that can emit light with lower directivity on the vertical plane than on the first vertical plane. This planar illumination device can be realized, for example, by providing an optical element having the same function as the first light diffusing unit 120 on the light emission surface of the illumination device 110 of the first embodiment. When such a planar illumination device is used, there is no need to provide the first light diffusing means as described above, and a display element having a light modulation function is provided above the illumination device and another display device is provided on the first vertical plane. A display device can be configured by providing light diffusion means for diffusing light so as to reduce the unevenness in luminance as compared with a surface.

[0100]

According to the display device of the present invention, the light emitted from the illuminating device is diffused in a predetermined direction by the first diffusing means, and then is incident on the display element, and the light modulated by the display element is emitted. Since the light is diffused in the azimuth different from the above azimuth by the second diffusion means, a good image can be provided in a wide viewing angle range in any azimuth (for example, the vertical direction and the horizontal direction of the display panel).

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a display device according to a first embodiment of the present invention.

FIGS. 2A and 2B are graphs showing emission angle characteristics with respect to luminance of light emitted from a lighting device and light emitted from a first light diffusion unit according to the first embodiment of the present invention; FIG. (B) shows the emission angle characteristic on another surface.

FIG. 3 is a perspective view schematically illustrating a change in directivity of light passing through the display device according to the first embodiment of the present invention.

4A and 4B are diagrams illustrating viewing angle characteristics of a display device according to Embodiment 1 of the present invention in comparison with a conventional display device. FIG. 4A illustrates viewing angle characteristics on a certain surface, and FIG. 4B illustrates another surface. Shows the viewing angle characteristics at.

FIG. 5 is a perspective view illustrating a display device according to a second embodiment of the present invention.

6A and 6B are diagrams illustrating emission angle characteristics with respect to luminance of light emitted from a lighting device and light emitted from a first light diffusing unit according to a second embodiment of the present invention. FIG. (B) shows the emission angle characteristic on another surface.

FIGS. 7A and 7B are diagrams illustrating viewing angle characteristics of a display device according to a second embodiment of the present invention in comparison with a conventional display device. FIG. 7A illustrates viewing angle characteristics on a certain surface, and FIG. Shows the viewing angle characteristics at.

FIG. 8 is a perspective view showing a display device according to Embodiment 3 of the present invention.

9A and 9B are diagrams illustrating emission angle characteristics relating to luminance of light emitted from a first light diffusing unit according to a third embodiment of the present invention, wherein FIG. 9A illustrates emission angle characteristics on a certain surface, and FIG.
Indicates the emission angle characteristics on the other surface.

FIG. 10 is a diagram illustrating emission angle characteristics with respect to luminance of light emitted from a lighting device according to a third embodiment of the present invention;
(A) shows an emission angle characteristic on a certain surface, and (b) shows an emission angle characteristic on another surface.

11A and 11B are diagrams illustrating viewing angle characteristics of a display device according to a third embodiment of the present invention, wherein FIG. 11A illustrates viewing angle characteristics on a certain surface, and FIG. 11B illustrates viewing angle characteristics on another surface.

FIG. 12 is a diagram showing viewing angle characteristics of a conventional display device;
(A) shows viewing angle characteristics on a certain surface, and (b) shows viewing angle characteristics on another surface.

FIG. 13 is a perspective view showing a conventional display device.

FIG. 14 is a perspective view showing another conventional display device.

FIG. 15 is a perspective view showing still another conventional display device.

FIG. 16 is a diagram for explaining the operation of a prism film included in the illumination device of the conventional display device.

17A and 17B are diagrams illustrating emission angle characteristics of illumination light from the illumination device of the conventional display device illustrated in FIG. 13, where FIG. 17A illustrates emission angle characteristics on a certain surface, and FIG. Shows the emission angle characteristics at.

18A and 18B are diagrams showing emission angle characteristics of illumination light from the illumination device of the conventional display device shown in FIG. 14, wherein FIG. 18A shows the emission angle characteristics on a certain surface, and FIG. 4 shows an emission angle characteristic on a plane.

FIG. 19 is a perspective view showing directivity control means of the conventional display device shown in FIG.

20A and 20B are diagrams illustrating emission angle characteristics of illumination light from the illumination device of the conventional display device illustrated in FIG. 15, wherein FIG. 20A illustrates emission angle characteristics on a certain surface, and FIG. 4 shows an emission angle characteristic on a plane.

FIG. 21 is a perspective view schematically showing a twisted nematic liquid crystal display device.

FIG. 22 is a diagram for explaining a plane perpendicular to the light emitting surface and the direction of emitted light when light is emitted from a certain surface.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 liquid crystal display device 110 lighting device 111 light source 112 light reflection sheet 113 light diffusion plate 114 directivity control means 120 first light diffusion means 130 liquid crystal display element 140 second light diffusion means 200 liquid crystal display device 210 lighting device 211 light source 212 Light reflection sheet 213 light guide 214 directivity control means 220 first light diffusion means 230 liquid crystal display element 240 second light diffusion means 300 liquid crystal display device 310 lighting device 311 light source 312 light reflection sheet 314 directivity control means 320 First light diffusion means 330 Liquid crystal display element 340 Second light diffusion means

────────────────────────────────────────────────── ─── of the front page continued (51) Int.Cl. ⁷ identification mark FI theme Court Bu (reference) G09F 9/00 324 G09F 9/00 324 336 336G F -term (reference) 2H042 BA04 BA12 BA14 BA20 2H091 FA08X FA08Z FA21Z FA26X FA27X FA27Z FA31X FA41Z HA07 HA10 LA18 LA19 5G435 AA00 AA01 BB12 BB15 EE26 FF06 GG24 GG26 HH04 KK05 KK07 LL04 LL07 LL12 LL14 LL17

Claims (14)

[Claims] An illumination device that emits highly directional light having a bias in luminance according to an emission angle; a display element that can modulate light emitted from the illumination device; A first light diffusing means disposed between the display element and a second light diffusing means disposed on a side of the display element opposite to a side on which the first light diffusing means is disposed; The first light diffusing means diffuses the light on a first surface perpendicular to the light exit surface of the lighting device so as to reduce the deviation of the luminance of the light more than on other surfaces. The second light diffusing means is perpendicular to the light exit surface of the lighting device, and intersects the first surface.
A display device for diffusing the light so as to reduce the unevenness of the luminance of the light in the surface of the light emitting device than in the other surface. 2. The display device according to claim 1, wherein the first surface and the second surface are substantially orthogonal. 3. The display device according to claim 1, wherein the first light diffusing unit does not substantially reduce the deviation of the luminance of the light on the second surface. 4. The display device according to claim 3, wherein the second light diffusing unit does not substantially reduce the deviation of the luminance of the light on the first surface. 5. The display device according to claim 1, wherein a light modulation angle on the first surface of the display element is wider than a light modulation angle on the second surface. 6. The display device according to claim 1, wherein the display element includes a liquid crystal layer formed of a plurality of liquid crystal molecules that can assume a twisted alignment state in a thickness direction, and a pair of polarizers sandwiching the liquid crystal layer. 6. The display device according to any one of 5. 7. The display device according to claim 6, wherein the liquid crystal molecules located at the center in the thickness direction of the liquid crystal layer move in the second plane by applying a voltage. 8. The first diffusing unit is formed of a light transmissive material, and refracts or reflects light transmitted through the first diffusing unit on a light exit surface of the first diffusing unit. The display device according to claim 1, wherein the display device is capable of performing the following operations. 9. The display device according to claim 8, wherein the first diffusing unit includes a plurality of lenses extending in parallel with each other. 10. The display device according to claim 9, wherein the plurality of lenses extend in a direction perpendicular to a direction in which the first surface extends in an emission surface of the illumination device. 11. The display device according to claim 1, wherein the first light diffusing unit diffuses only light in a specific incident angle range on the first surface. 12. A spread illuminating device that emits light having a deviation in luminance according to an output angle, wherein a luminance according to the output angle is provided on a first surface perpendicular to a light output surface of the illuminating device. And the second surface perpendicular to the light exit surface of the illumination device and intersecting with the first surface has a lower luminance deviation according to the emission angle than the first surface. A planar illumination device that emits light. 13. The method according to claim 1, wherein the second surface diffuses the light so as to reduce the deviation of the luminance of the light as compared with the other surfaces, and the first surface substantially reduces the deviation of the luminance of the light. 13. The spread illuminating apparatus according to claim 12, further comprising a light diffusion unit that does not reduce the light. 14. A spread illuminating device according to claim 12,
A display device comprising: a display element capable of modulating light emitted from the planar illumination device; and a light diffusing unit that diffuses light transmitted through the display element. A display device, wherein light is diffused on one surface so as to reduce the deviation of the luminance of the light as compared with the other surface.