JP2006284831A - Electrooptical apparatus and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrooptical apparatus which can condense omnidirectional light made incident in a liquid crystal display panel and can be made further thin. <P>SOLUTION: The electrooptical apparatus is a liquid crystal apparatus having e.g. a pair of substrates. Light is made incident in the pair of substrates by a backlight. A micro lens is formed on an outer surface of the other substrate of the pair of substrates. The micro lens formed on the outer surface of the other substrate can condense light made incident from omniazimuth directions. Thereby, it is not needed to use a prism sheet for the backlight and thinness of the apparatus can be achieved. Light utilizing efficiency can be heightened to the maximum and a display screen having a wide viewing angle and high luminance can be provided as compared with a general liquid crystal display using the prism sheet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electro-optical device suitable for displaying various information.

  In the liquid crystal display device, a backlight is provided on the back side of the liquid crystal display panel in order to perform transmissive display. Generally, a backlight is a light source, a light guide plate that irradiates the back surface of the liquid crystal display panel with light from the light source as planar light, a sheet that diffuses light emitted from the light guide plate, and condenses the light. It is comprised as an illuminating device provided with the prism sheet etc. which do. The light incident on the light guide plate from the light source is repeatedly reflected between the light exit surface and the reflection surface of the light guide plate, and then exits from the light exit surface to the outside.

  Light emitted from the light guide plate enters the prism sheet. In the prism sheet, incident light can be refracted and emitted toward the liquid crystal display panel. Therefore, the prism sheet has a role of increasing the luminance of the liquid crystal display device. In a general liquid crystal display device, two prism sheets having different prism ridge directions are used in an overlapping manner. Accordingly, light incident in a direction perpendicular to the direction of the ridge line of each prism can be emitted toward the liquid crystal display panel, and the luminance of the liquid crystal display device can be increased. Further, in Patent Document 1, the direction of the ridge line of one prism is inclined with respect to the direction of the ridge line of the other prism, thereby eliminating interference (moire) with the linear elements of the liquid crystal display panel. .

  However, in the above example, only the light of the component perpendicular to the ridge line of each prism among the light incident on the prism sheet can be condensed toward the liquid crystal display panel. Further, since it is necessary to use two prism sheets, there is a problem from the viewpoint of thinning the liquid crystal display device.

JP-A-8-68997

  The present invention has been made in view of the above points, and it is an object of the present invention to provide an electro-optical device that can collect light in all directions incident on a liquid crystal display panel and can be thinned. And

  In one aspect of the present invention, an electro-optical device includes a pair of substrates, a backlight that is disposed on one substrate side of the pair of substrates, and makes light incident on the pair of substrates, and the pair of substrates. A plurality of microlenses formed on the outer surface of the other substrate.

  The electro-optical device is a liquid crystal display device having a pair of substrates, for example. The backlight makes light incident on the pair of substrates. A microlens is formed on the outer surface of the other substrate of the pair of substrates. The microlens formed on the outer surface of the other substrate can collect light incident from all directions. Therefore, it is not necessary to use a prism sheet for the backlight, and the apparatus can be thinned. Further, as compared with a general liquid crystal display device using a prism sheet, the light use efficiency can be maximized, and a display screen with a wide viewing angle and high luminance can be realized.

  In one aspect of the electro-optical device, the plurality of microlenses are formed in the same pattern for each pixel. The pixel here refers to a sub-pixel that displays one color. Thereby, since the light emission efficiency in each pixel can be made equal, it is possible to suppress the occurrence of light brightness and darkness in each pixel, and the light distribution characteristics of the entire liquid crystal display panel can be kept constant. .

  In another aspect of the above electro-optical device, the plurality of microlenses are irregularly formed in one pixel. Thereby, since the refracted light by a microlens can be scattered, it can suppress that a display screen looks iridescent.

  In another aspect of the above electro-optical device, one microlens is formed over one pixel in the plurality of microlenses. As a result, a place where no microlens is present does not occur in one pixel, so that light can be efficiently collected.

  In another aspect of the electro-optical device, the electro-optical device further includes a refractive layer that is applied on the outer surface of the other substrate and is made of a resin material. Thereby, the unevenness | corrugation on the surface of the said other board | substrate which generate | occur | produces by forming a microlens can be made flat, and it becomes possible to adhere | attach an upper polarizing plate.

  In another aspect of the above electro-optical device, the refractive layer has a flat outer surface. Thereby, the light condensed by the microlens can be emitted as it is without being refracted on the outer surface of the refractive layer.

  In another aspect of the electro-optical device, the plurality of microlenses are formed in a concave shape on the outer surface of the other substrate. Thereby, processing on the outer surface of the other substrate when forming the microlens can be prepared.

  In another aspect of the electro-optical device, the resin material has a light refractive index higher than that of the other substrate. Thereby, the thickness of the refractive layer can be reduced, and the entire apparatus can be reduced in thickness.

  In another aspect of the present invention, an electronic apparatus including the electro-optical device as a display unit can be configured.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First embodiment]
(Liquid crystal display device)
First, the configuration of the liquid crystal display device according to the first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a liquid crystal display device 100 according to the first embodiment. In FIG. 1, an active matrix driving method using a TFD element and a completely transmissive liquid crystal display device is taken as an example.

  In FIG. 1, the liquid crystal display device 100 is roughly divided into a liquid crystal display panel 30 and a backlight 50.

  In the liquid crystal display panel 30, an element substrate 91 and a color filter substrate 92 disposed so as to face the element substrate 91 are bonded to each other through a frame-shaped seal member 3, and liquid crystal is sealed inside the liquid crystal layer 4. Is formed. A conductive member 7 such as a plurality of gold particles is mixed in the frame-shaped seal member 3.

  The upper substrate 2 is formed of glass or the like, and on the inner surface of the upper substrate 2, colored layers 6 </ b> R and 6 </ b> G made of any of R (red), G (green), and B (blue) are provided for each subpixel SG. , 6B are formed. A color filter is constituted by the colored layers 6R, 6G, and 6B. In the figure, a pixel G indicates an area for one color pixel composed of RGB sub-pixels SG. In the following description or drawings, when a component is shown regardless of color, it is simply written as “colored layer 6”, and when a component is shown by distinguishing colors, for example, “colored layer 6R” I will write as follows.

  A black light-shielding layer BM is formed between the sub-pixels SG in order to prevent light from being mixed from one sub-pixel to the other sub-pixel, with the adjacent sub-pixels SG being separated. The black light shielding layer BM can be made of a black resin material, for example, a black pigment dispersed in a resin.

  A protective layer 18 made of a transparent resin or the like is formed on the colored layer 6 and the black light shielding layer BM. The protective layer 18 has a function of smoothing the level difference of the color filter between the colors, and is corroded or contaminated by chemicals used during the manufacturing process of the color filter substrate 92 and the liquid crystal display device 100 according to the present embodiment. Therefore, it has a function of protecting the colored layer 6. On the surface of the protective layer 18, a transparent electrode (scanning electrode) 32 such as striped ITO (Indium-Tin Oxide) is formed. One end of the transparent electrode 32 extends into the seal member 3 and is electrically connected to the conducting member 7 in the seal member 3.

  A large number of concave hemispherical microlenses 10 are formed on the outer surface of the upper substrate 2. A refractive layer 5 is further formed on the outer surface of the upper substrate 2 on which many microlenses 10 are formed. The refractive layer 5 is made of a resin material having a higher refractive index of light than that of the glass that is the material of the upper substrate 2.

  On the other hand, the lower substrate 1 is formed of glass or the like, and the scanning lines 31 are formed on the inner surface of the lower substrate 1 at regular intervals. A TFD element 21 and a pixel electrode 11 are formed on the inner surface of the lower substrate 1 for each subpixel. The scanning line 31 is electrically connected to the pixel electrode 11 via the corresponding TFD element. A voltage is applied between the pixel electrode 11 and the transparent electrode 32 to control the orientation of the liquid crystal in the liquid crystal layer 4 to change the light transmittance and perform gradation display.

  A lower polarizing plate 8 is disposed on the outer surface of the lower substrate 1, and an upper polarizing plate 9 is disposed on the outer surface of the refractive layer 5. A backlight 50 is disposed below the lower polarizing plate 8.

  The refractive layer 5 is made of a resin material, and is applied to a certain thickness on the outer surface of the upper substrate 2. Therefore, the surface of the outer surface of the upper substrate 2 whose surface is uneven due to the formation of the microlens 10 can be flattened by applying the refractive layer 5. In other words, the thickness of the refractive layer 5 is a thickness necessary for flattening the outer surface of the refractive layer 5. Thus, by providing the refractive layer 5 between the upper polarizing plate 9 and the upper substrate 2, the upper polarizing plate 9 can be bonded onto the upper substrate 2.

  Next, the backlight 50 will be described. The backlight 50 includes a light guide 51 and a light source 55 on the end surface of the light guide plate 51. The light source 55 is equipped with an LED 56. Further, the backlight 50 includes a reflective sheet 52 on the reflective surface side of the light guide plate 51, and a diffusion sheet 53 for emitting light uniformly on the light output surface side of the light guide plate 51.

  When the LED 56 of the light source 55 emits light, light enters from the end face of the light guide 51. The light that has entered the light guide 51 propagates through the light guide 51 and is uniformly emitted to the outside toward the liquid crystal display panel 30 by the reflection sheet 52 and the diffusion sheet 53. Of the irradiation light irradiated on the liquid crystal display panel 30 in this way, the illumination light traveling along the path T shown in FIG. 1 passes through the colored layer 6 and the liquid crystal layer 4 and is condensed by the lens effect of the microlens 10. To the observer. In this case, the irradiation light has a predetermined hue and brightness by transmitting through the colored layer 6 and the liquid crystal layer 4. Thus, a desired color display image is visually recognized by the observer.

(Light collection by microlens)
Next, light collection by the microlens 10 will be described. As described above, many concave microlenses 10 are formed on the outer surface of the upper substrate 2.

FIG. 2 shows an enlarged view of the microlens 10. FIG. 2A shows an enlarged cross-sectional view of the microlens 10, and FIG. 2B shows an enlarged plan view of the microlens 10.
In the drawings described below, of the light traveling along the path T, light before entering the microlens is indicated by a broken-line arrow as light T_in, and light after entering the microlens is indicated as light T_out. It shall be indicated by a solid line arrow.

  As shown in the enlarged plan view of the microlens 10 in FIG. 2A, the microlens 10 has a concave hemispherical shape. In the enlarged plan view of the microlens 10 in FIG. 2B, the incident direction of the light T_in that can be refracted and condensed by the microlens 10 is shown, and the incident light T_in is refracted from all directions. You can see that Accordingly, the microlens 10 can refract the light T_in incident from all directions equally in the light collecting direction by the lens effect and emit the light T_in as the light T_out. From this, it can be seen that the microlens 10 has the same function as the prism of the prism sheet disposed in the backlight of a general liquid crystal display device. However, the prism of the prism sheet can refract only light incident perpendicularly to the ridgeline of the prism, whereas the microlens 10 can refract light incident from all directions. Therefore, the microlens 10 can increase the light use efficiency to the maximum and increase the luminance as compared with the prism of the prism sheet.

  Further, since the prism of the prism sheet refracts only the light incident perpendicularly to the ridgeline of the prism, the general liquid crystal display device having the prism sheet has a visual dependency of luminance. On the other hand, in the liquid crystal display device according to the first embodiment, the microlens 10 can refract light incident from all directions, so that the visual dependency of luminance does not occur. Therefore, the liquid crystal display device according to the first embodiment can realize a display screen with a wide viewing angle and high brightness without using a prism sheet.

  Next, the relationship between the refractive index of the refractive layer 5 and the light collection distance by the microlens 10 will be described. When the refractive index of light on the upper substrate 2 is n2, the refractive index of light on the refractive layer 5 is n5, the incident angle of light on the upper substrate 2 is i, and the refractive angle of light on the refractive layer 5 is r, these relationships are From Snellius's law, it can be expressed by the following equation.

sin (i) / sin (r) = n5 / n2 (1)
Therefore, when the refractive index of the light of the refractive layer 5 is higher than the refractive index of the light of the upper substrate 2, n5 / n2 is larger than 1, so that the refractive angle r is larger than the incident angle i from (1). Get smaller. On the other hand, when the refractive index of the light of the refractive layer 5 is lower than the refractive index of the light of the upper substrate 2, n5 / n2 is smaller than 1, so that the refraction angle r is larger than the incident angle i from (1). growing.

  FIG. 3A shows a light path due to a difference in refractive index of light between the refractive layer 5 and the upper substrate 2. Here, the incident angle of light on the upper substrate 2 is “γ1”. When the refractive angle of light when the refractive index of light of the refractive layer 5 is higher than the refractive index of light of the upper substrate 2 is “α1”, the refractive angle α1 is smaller than the incident angle γ1. On the other hand, when the refractive angle of light when the refractive index of light of the refractive layer 5 is lower than the refractive index of light of the upper substrate 2 is “β1”, the refractive angle β1 is larger than the incident angle γ1 of light. Therefore, as shown in FIG. 3A, the refraction angle α1 is smaller than the refraction angle β1.

  In order to reduce the thickness of the entire device, it is desirable that the thickness of the refractive layer 5 be as thin as possible within a range in which flatness necessary for bonding the upper polarizing plate 9 can be secured. Therefore, since the condensing distance by the microlens 10 is preferably shorter, as shown in FIG. 3A, the refraction angle in the refraction layer 5 becomes the refraction angle α1 rather than the refraction angle β1. Is preferred. Therefore, in the liquid crystal display device 100 according to the first embodiment, a resin material having a light refractive index higher than the light refractive index of the upper substrate 2 is used as the material of the refractive layer 5.

  Since glass (refractive index = 1.50) is used as the material of the upper substrate 2, the resin material of the refractive layer 5 is, for example, polycarbonate (refractive index = 1.58), polystyrene (refractive index = 1. 59) and an epoxy resin (refractive index = 1.60) are preferable. By doing in this way, the thickness of the refractive layer 5 can be made thin and the whole apparatus can be made thin.

  Further, it is desirable to flatten the outer surface of the refractive layer 5. If the surface of the outer surface of the refraction layer 5 has irregularities, different light refractions occur in the respective irregularities, and the light condensing effect by the microlens 10 is diminished. By flattening the surface of the outer surface of the refractive layer 5, the light condensed by the microlens can be emitted as it is without being refracted on the surface of the outer surface of the refractive layer.

  In the liquid crystal display device 100 according to the first embodiment, it is assumed that the concave hemispherical microlens 10 is formed on the upper substrate 2, but instead of the concave hemispherical microlens 10, A convex hemispherical microlens 10b may be formed.

  FIG. 3B shows light paths according to the difference in the refractive index of light between the refractive layer 5 and the upper substrate 2 when the convex hemispherical microlenses 10 b are formed on the upper substrate 2. Here, the incident angle of light on the upper substrate 2 is “γ2”. If the refractive angle of light when the refractive index of light of the refractive layer 5 is higher than the refractive index of light of the upper substrate 2 is “α2”, the refractive angle α2 is smaller than the incident angle γ2. On the other hand, if the light refraction angle when the light refraction index of the refraction layer 5 is lower than the light refraction index of the upper substrate 2 is “β2”, the refraction angle β2 is larger than the incident angle γ2. Therefore, as shown in FIG. 3B, the refraction angle α2 is smaller than the refraction angle β2. For the same reason as described above, it is better that the condensing distance by the microlens 10b is shorter. Therefore, as shown in FIG. 3B, the light refraction angle is preferably the refraction angle β2. It is. Therefore, when the convex hemispherical microlens 10 b is formed on the upper substrate 2, a resin material having a refractive index of light lower than the refractive index of light of the upper substrate 2 is used as the material of the refractive layer 5. Used. Specifically, an ethylene resin (refractive index = 1.49) is used as the resin material of the refractive layer 5 in this case. Furthermore, when the material of the refractive layer 5 is not limited to a resin material, magnesium fluoride (refractive index = 1.37) can also be used.

  The concave hemispherical microlens 10 is formed by coating the surface of the upper substrate 2 with a photosensitive resin such as a photoresist, patterning it into the shape of the microlens, and etching with fluorine gas. It is easily formed on the surface. Therefore, in the liquid crystal display device 100 according to the first embodiment, by adopting the concave hemispherical microlens 10 as the microlens, processing for forming the microlens can be easily performed.

(Arrangement of microlenses)
Next, the arrangement of the microlenses 10 on the upper substrate 2 will be described. FIG. 4 is an enlarged plan view showing the arrangement of the microlenses 10 formed on the upper substrate 2 for each of the RGB sub-pixels SG. As shown in FIG. 4, the diameter of the microlens 10 is smaller than the short side of the subpixel SG, and the microlenses 10 of various sizes are densely formed in one subpixel SG. By forming the microlenses 10 densely, more microlenses 10 can be arranged on the upper substrate 2.

  The light incident on the microlens 10 is RGB light transmitted through the colored layer 6, and the RGB light has a different wavelength for each color. Since the refractive index of light in the upper substrate 2 and the refractive layer 5 varies depending on the wavelength of light, the refractive angle of light refracted by the microlens 10 is different for each color. Therefore, when the microlenses 10 are regularly arranged in a specific direction and formed on the upper substrate 2, the same color refracted by each microlens 10 is between two microlenses 10 that refract the same color light. Light exits in the same specific direction and is intensified by interference. On the other hand, between the two microlenses 10 that refract light of different colors, the light refracted by each microlens 10 is emitted in different directions. In this way, the light emitted from the subpixels of each color of RGB causes a light dispersion phenomenon, and thus the observer may have a rainbow color on the display screen. In the liquid crystal display device 100 according to the first embodiment, the microlenses 10 are irregularly (randomly) formed on the surface of the upper substrate 2 in one subpixel SG. Thereby, since the refracted light of the light of the same color can be emitted in various directions, interference of light in a specific direction can be prevented, and the display screen can be prevented from appearing in rainbow colors.

  Further, as shown in FIG. 4, the microlens 10 formed on the surface of the upper substrate 2 is formed in the same pattern for each subpixel SG. Thereby, the light emission efficiency in each sub-pixel SG can be made equal. Therefore, it is possible to suppress the occurrence of light brightness and darkness for each sub-pixel, and the light distribution characteristics of the entire liquid crystal display panel can be kept constant.

[Second Embodiment]
Next, the configuration of the liquid crystal display device 100a according to the second embodiment of the present invention will be described. FIG. 5 is a cross-sectional view schematically showing a schematic configuration of the liquid crystal display device 100a according to the second embodiment. FIG. 6 is an enlarged view of the microlens 10a in the liquid crystal display device 100a according to the second embodiment. 6A shows an enlarged plan view of the micro lens 10a, FIG. 6B shows an Aa-Ab cross section of the micro lens 10a, and FIG. 6C shows a Ba-Bb cross section of the micro lens 10a. Indicates.

  In the liquid crystal display device 100 according to the first embodiment, the microlenses 10 having various sizes are irregularly formed on the upper substrate 2 in one subpixel SG. On the other hand, in the liquid crystal display device 100a according to the second embodiment, as shown in FIGS. 6A to 6C, one microlens 10a having a concave curved surface shape is formed on one entire subpixel SG. It is formed on the upper substrate 2. By doing in this way, like the microlens 10 of the liquid crystal display device 100 according to the first embodiment, the microlens 10a can collect the light transmitted through the liquid crystal layer 4 and the colored layer 6 by refraction. it can.

  Furthermore, in the liquid crystal display device 100a according to the second embodiment, by forming one microlens 10a in one entire subpixel SG, a place where no microlens exists can be generated in one subpixel. Therefore, the light can be collected efficiently.

[Electronics]
Next, specific examples of electronic devices to which the liquid crystal display device 100 according to the present invention can be applied will be described with reference to FIG.

  First, an example in which the liquid crystal display device 100 according to the present invention is applied to a display unit of a portable personal computer (so-called notebook personal computer) will be described. FIG. 7A is a perspective view showing the configuration of this personal computer. As shown in the figure, the personal computer 710 includes a main body 712 having a keyboard 711 and a display 713 to which the liquid crystal display panel according to the present invention is applied.

  Next, an example in which the liquid crystal display device 100 according to the present invention is applied to a display unit of a mobile phone will be described. FIG. 7B is a perspective view showing the configuration of the mobile phone. As shown in the figure, the cellular phone 720 includes a plurality of operation buttons 721, a reception port 722, a transmission port 723, and a display unit 724 to which the liquid crystal display device 100 according to the present invention is applied.

  Electronic devices to which the liquid crystal display device 100 according to the present invention can be applied include a liquid crystal television and a viewfinder in addition to the personal computer shown in FIG. 7A and the mobile phone shown in FIG. Type / monitor direct-view type video tape recorder, car navigation device, pager, electronic notebook, calculator, word processor, workstation, videophone, POS terminal, digital still camera, etc.

It is sectional drawing which shows schematic structure of the liquid crystal display device which concerns on 1st Embodiment. It is an enlarged view of the micro lens of the liquid crystal display device which concerns on 1st Embodiment. It is the schematic diagram shown about the shape and refractive index of the micro lens. It is the top view which showed arrangement | positioning of the micro lens in every sub pixel. It is sectional drawing which shows schematic structure of the liquid crystal display device which concerns on 2nd Embodiment. It is an enlarged view of the micro lens of the liquid crystal display device which concerns on 2nd Embodiment. It is the schematic which shows the electronic device to which the illuminating device of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower board | substrate, 2 Upper board | substrate, 5 Refractive layer, 10 Micro lens, 6 Colored layer, 30 Liquid crystal display panel, 50 Backlight, 100 Liquid crystal display device

Claims (9)

A pair of substrates;
A backlight that is disposed on one side of the pair of substrates and makes light incident on the pair of substrates; and
An electro-optical device comprising: a plurality of microlenses formed on an outer surface of the other substrate of the pair of substrates.   The electro-optical device according to claim 1, wherein the plurality of microlenses are formed in the same pattern for each pixel.   The electro-optical device according to claim 1, wherein the plurality of microlenses are irregularly formed in one pixel.   The electro-optical device according to claim 1, wherein one of the plurality of microlenses is formed on one pixel.   The electro-optical device according to claim 1, further comprising a refractive layer that is applied on a surface of the outer surface of the other substrate and is made of a resin material.   The electro-optical device according to claim 5, wherein the refractive layer has a flat outer surface.   The electro-optical device according to claim 1, wherein the plurality of microlenses are formed in a concave shape on an outer surface of the other substrate.   The electro-optical device according to claim 7, wherein the resin material has a light refractive index higher than a light refractive index of the other substrate. An electronic apparatus comprising the electro-optical device according to claim 1 in a display unit.

Images