Lighting device, liquid crystal display device, and electronic apparatus

A lighting device of the invention includes: a plurality of light sources; and an optical waveguide, wherein light emitted from the plurality of light sources is incident from a side of the optical waveguide and then emitted from one main plane of the optical waveguide. The optical waveguide includes a first inclined plane for reflecting light emitted from a first light source and then emitting the light from the one main plane, and a second inclined plane for reflecting light emitted from a second light source and then emitting the light from the one main plane at an exit angle different from the light emitted from the first light source, and wherein each of the light sources is independently driven.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a lighting device, a liquid crystal display device, and an electronic apparatus.

2. Related Art

In recent years, liquid crystal display devices, such as liquid crystal panels, are widely installed in the image display units of various electronic apparatuses. For example, such liquid crystal display devices are suitably used in the display units of mobile devices such as mobile phones due to their slimness, low weight and low power consumption. The liquid crystal display devices mainly include a liquid crystal panel in which a liquid crystal layer is interposed between a pair of substrates, and a lighting device (backlight) disposed on the non-viewing screen side of the liquid crystal panel. Further, the orientation state of liquid crystal molecules is controlled by applying an electric field to the liquid crystal layer by transparent electrodes formed at the sides of the liquid crystal layer interposed between the pair of substrates, so that the incident light from the lighting device is modulated, thereby displaying an image.

The above-mentioned lighting device is mainly composed of a rectangular optical waveguide made of a light-transmissive material and a light source, such as a light-emitting diode (LED), which is disposed adjacent to the optical waveguide. The optical waveguide is formed with patterns of grooves or protrusions. Further, the light emitted from the light source and which is also incident from the side of the optical waveguide is reflected from the grooves or protrusions to be emitted from the main plane of the optical waveguide toward the liquid crystal panel. Japanese Unexamined Patent Application Publication Nos. 2001-133776 and 2001-184923 are examples of the related art.

However, because the above-mentioned mobile devices are widely used in public places, many mobile device users are frequently concerned about revealing their personal information, etc. to others while using it. On the other hand, because the liquid crystal display devices generally have a narrow viewing angle, it is difficult to read the display from a direction deviating from the viewing angle. Therefore, liquid crystal display devices have a usability problem.

SUMMARY

An advantage of the present invention is that it provides a lighting device in which the exit angle of emitted light can be changed.

Another advantage of the invention is that it provides an electro-optical device and an electronic apparatus in which the range of a viewing angle can be varied.

A lighting device of the invention includes: a plurality of light sources; and an optical waveguide, wherein light emitted from the plurality of light sources is incident from a side of the optical waveguide and then emitted from one main plane of the optical waveguide, wherein the optical waveguide includes a first inclined plane for reflecting light emitted from a first light source and then emitting the light from the one main plane, and a second inclined plane for reflecting light emitted from a second light source and then emitting the light from the one main plane at an exit angle different from the light emitted from the first light source, and wherein each of the light sources is independently driven.

According to this configuration, since each of the light sources is independently driven, the exit angle of the emitted light can be changed.

Further, it is preferable that the plurality of light sources are respectively disposed at different corners of the optical waveguide.

According to this configuration, since light can be incident on the entire optical waveguide, a dead angle region can be prevent when light is incident on the optical waveguide. It is thus possible to provide a compact lighting device in which light irregularities do not occur.

Furthermore, it is preferable that the lighting device further includes a light reflective sheet disposed on the other main plane of the optical waveguide.

According to this configuration, light leaked from the other main plane of the optical waveguide is reflected and then incident on the optical waveguide again. It is thus possible to increase the brightness of light emitted from the one main plane of the optical waveguide.

Further, it is preferable that the lighting device further includes a prism sheet disposed on the one main plane of the optical waveguide, wherein the prism sheet has indentations and protrusions at a side opposite to the one main plane of the optical waveguide, and refracts light emitted from the optical waveguide.

In addition, it is preferable that, in the prism sheet, the vertex angle of a prism, which is opposite to the one main plane of the optical waveguide, is set to 55° to 70°.

According to this configuration, not only the surface brightness of the emitted light can be made uniform, but also the reflection on the inclined plane can be prevented.

Furthermore, it is preferable that the gradient angle of the first inclined plane is set to 0.5° to 5°, and the gradient angle of the second inclined plane is set to 20° to 50°.

The prism sheet has a property of converting light having a wide exit angle, which is emitted from the optical waveguide, into light having a small exit angle, which is emitted from the prism sheet, and converting light of having a small exit angle, which is emitted from the optical waveguide, into light having a wide exit angle, which is emitted from the prism sheet. Therefore, not only the light from the first light source can be emitted at a small exit angle, but also the light from the second light source can be emitted at a wide exit angle. Accordingly, since each of the light sources is independently driven, the size of an exit angle can be changed.

Further, it is preferable that the lighting device further includes a diffuser sheet disposed on the one main plane of the optical waveguide, wherein the diffuser sheet diffuses the light emitted from the optical waveguide, and wherein the gradient angle of the first inclined plane is set to 35° to 50°, and the gradient angle of the second inclined plane is set to 5° to 35° or 50° to 70°.

According to this configuration, it is possible that the light from the first light source is emitted at a small exit angle, while the light from the second light source is emitted at a wide exit angle. Accordingly, since each of the light sources is independently driven, the size of an exit angle can be changed.

Furthermore, it is preferable that the inclined planes are provided in grooves and/or protrusions formed in the main plane of the optical waveguide, respectively.

According to this configuration, it is easy to control the exit angle of light unlike an embossing process or a blast process. Further, since inclined planes can be consecutively formed, the degree of freedom that changes the density of the inclined planes can be increased. Accordingly, light from the light source can be efficiently reflected and emitted from the optical waveguide.

Further, it is preferable that the inclined planes are disposed approximately in a concentric shape around each of the light sources.

According to this configuration, the light from the light source is vertically incident with respect to the extending direction of the inclined plane. Thus, the effective gradient angle of the inclined plane can be easily set so that the light is emitted from the optical waveguide at a predetermined exit angle.

Meanwhile, a liquid crystal display device of the invention includes the above-mentioned lighting device.

According to this configuration, by driving only the first light source, image display having a narrow viewing angle can be realized. Further, by driving only the second light source, image display having a wide viewing angle can be realized. It is thus possible to provide a liquid crystal display device having a variable viewing angle.

Meanwhile, an electronic apparatus of the invention includes the above-mentioned liquid crystal display device.

According to this configuration, it is possible to provide an electronic apparatus having a variable viewing angle.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, which will be referred to in the following description, each component has different dimensions and a reduced scale from its actual dimensions and scale so it can be easily viewed in the figures. Further, hereinafter, one main plane of an optical waveguide at the side of a liquid crystal panel will be defined as ‘front surface’, and the other main plane of the optical waveguide at an opposite side thereof will be defined as ‘rear surface’.

Lighting Device

First Embodiment

FIGS. 1A and 1Bare explanatory diagrams illustrating a lighting device according to a first embodiment of the invention. The lighting device10according to the embodiment mainly includes an optical waveguide1having a rectangular flat plate shape, a first light source2and a second light source3both of which are disposed in opposite to corners of the optical waveguide1, a reflective sheet5disposed on a rear surface of the optical waveguide1, and a diffuser sheet4disposed on a front surface of the optical waveguide1.

FIG. 1Ais a plan view of the lighting device according to a first embodiment of the invention, which is a cross-sectional view of the lighting device taken along line C-C ofFIG. 1B. The lighting device10of the embodiment includes the optical waveguide1of a rectangular flat panel shape. The optical waveguide1is formed about 0.6 mm in thickness using a light-transmissive material such as an acrylic resin. Further, longitudinal corners1A and1B at both ends of one side of the optical waveguide1are truncated so that they are approximately orthogonal to straight lines that connect other corners diagonal to the corners1A and1B, respectively.

The first and second light sources2and3are disposed opposite to the truncated sides. At this time, the first and second light sources2and3are used as the light sources of the lighting device according to the embodiment. Although it is not specially limited, a solid light source, such as a light emitting diode (LED) having a small size and low power consumption, is suitable for the light sources of the lighting device according to the embodiment. Further, in the embodiment, it has been described that the two light sources are disposed in front of the corners1A and1B, respectively, at the both ends of the one side of the optical waveguide1. Instead of that, the light sources may be disposed at corners of both ends of diagonal lines of the optical waveguide1. It is also to be noted that the number of light sources is not limited to two, but additional light sources can be disposed at other corners other than the above-described corners.

However, a point light source, such as an LED, emits light in a radial direction within a range of about ±70° from its optical axis (a straight line that connects the centers of a light source, a lens, etc. in an optical system). For this reason, if the light source is disposed on the side surface of the optical waveguide1, light is not incident on the optical waveguide1within a range exceeding about ±70° from the optical axis. Thus, there occurs a dead angle region of light incidence in the optical waveguide1. This causes light irregularities to occur in the lighting device10. On the other hand, in the lighting device according to the embodiment, since the light sources are disposed at the corners of the optical waveguide1, the light can be incident on the entire optical waveguide1. Thus, the dead angle region of light incidence does not occur in the optical waveguide1. Therefore, a compact lighting device without light irregularities can be provided, and an electro-optical device and an electronic apparatus having excellent display quality can be thus provided.

FIG. 1Bis a lateral cross-sectional view of the lighting device taken along line A-A ofFIG. 1A. As shown inFIG. 1B, the reflective sheet5is disposed on a rear surface1D of the optical waveguide1. The reflective sheet5is disposed in such a way that a front surface of the reflective sheet5opposite to the optical waveguide1is a specular reflection face. Thus, the reflective sheet5can reflect light leaked from the rear surface of the optical waveguide1and then allow it to be incident on the optical waveguide1again. It is thus possible to increase the brightness of the light output from the front surface of the optical waveguide1. Meanwhile, the diffuser sheet4is disposed on a front surface1C of the optical waveguide1. The diffuser sheet4can be formed of an acrylic sheet, etc. in which a diffusing agent is distributed. The diffuser sheet4can make the surface brightness of the light output from the lighting device uniform, and can also prevent the light from reflecting from the grooves or protrusions (to be described later).

Furthermore, a liquid crystal panel100is disposed on a light exit surface of the diffuser sheet4in the lighting device10, with light-shielding tapes8for preventing the leakage of light, and the like being disposed therebetween. The liquid crystal panel100constitutes a liquid crystal display device to be described in detail later.

Inclined planes for reflecting light from the light sources toward the liquid crystal panel100are disposed in the optical waveguide1.

FIG. 2is an explanatory diagram illustrating the shape of an inclined plane according to an aspect of the invention, which shows a lateral cross-sectional view of a portion corresponding to line A-A inFIG. 1A. Further, although an inclined plane corresponding to the first light source2will be described below as an example, the same is true of an inclined plane corresponding to the second light source3. InFIG. 2A, grooves20are formed in the rear surface1D of the optical waveguide1. In this case, an inclined plane at the side of the light source2in the grooves20becomes an effective inclined plane22for reflecting light from the light source2toward the liquid crystal panel. Furthermore, as shown inFIG. 2B, protrusions25can be formed on the rear surface1D of the optical waveguide1. In this case, an inclined plane at the side opposite to the light source2in the grooves20becomes an effective inclined plane22for reflecting light from the light source2toward the liquid crystal panel. Meanwhile, as shown inFIG. 2C, grooves20can be formed in the front surface1C of the optical waveguide1. Moreover, as shown inFIG. 2D, protrusions25can be formed on the front surface1C of the optical waveguide1. In addition, effective inclined planes of the first light source2and the second light source3may not be located on the same surface. Incidentally, inFIGS. 2C and 2D, the rear surface1D of the optical waveguide1can be parallel to the liquid crystal panel100, or can be inclined against the liquid crystal panel100so that it can efficiently reflect light from the light source2toward the liquid crystal panel100.

Referring back toFIG. 1, in the embodiment, a case where the grooves20are formed in the rear surface1D of the optical waveguide1will be described as an example.

In the embodiment, the light from the respective light sources2and3is reflected and then emitted from the optical waveguide1at different exit angles. That is, while the light from the first light source2is emitted from the optical waveguide1at a small exit angle, the light from the second light source3is emitted from the optical waveguide1at a wide exit angle. At this time, the exit angle refers to an angle formed by the emitted light and an optical axis (a normal direction of the optical waveguide1) of the lighting device10. As such, in order for the light from the first and second light sources2and3to be emitted from the optical waveguide1at different exit angles, grooves20aare formed corresponding to the first light source2, and grooves20band20care formed corresponding to the second light source3. Further, the grooves20aand the grooves20band20cinclude effective inclined planes having different effective gradient angles.

Moreover, the grooves20acorresponding to the first light source2, and the grooves20band20ccorresponding to the second light source3are each formed in a concentric shape around the light sources2and3. In this case, light from each of the light sources is vertically incident to the extending direction of each groove. Thus, in order for the light to be reflected and then emitted from the optical waveguide1at a predetermined exit angle, the effective gradient angle of the effective inclined plane of each groove can be easily set.

Further, the first and second light sources2and3are connected to a control unit9. The first and second light sources2and3can be independently driven under the control of the control unit9.

FIG. 3is an explanatory diagram illustrating the shape of the grooves20acorresponding to the first light source and the light reflection by the grooves20a. There is shown, inFIG. 3, a cross-sectional view taken along line A-A ofFIG. 1A. In the embodiment, the thickness H of the optical waveguide1is about 0.6 mm, whereas the depth h of the grooves20ais as small as about 10 μm. For this reason, light11parallel to the front surface1C of the optical waveguide1is rarely incident on the grooves20a, but light12inclined several degrees from the surface of the optical waveguide1, for example, by about 5°, is mainly incident on the grooves20a. Therefore, in order for the inclined light12to be reflected approximately parallel to the normal direction of the optical waveguide1, an effective gradient angle θ of an effective inclined plane22in the grooves20ais set to 35° to 50°. If reflected light14by the effective inclined plane22is emitted from the optical waveguide1and then incident on the diffuser sheet4, it is converted into diffused light18. The diffused light18is distributed in a narrow angular range α around the optical axis of the lighting device. Further, by allowing the diffused light18to be incident on the liquid crystal panel100shown inFIG. 1B, image display having a narrow viewing angle can be realized.

FIG. 4is an explanatory diagram illustrating the shape of the grooves20bcorresponding to the second light source3and the light reflection by the grooves20b.FIG. 4shows a cross-sectional view taken along line B-B ofFIG. 1A. Further, in order to emit light from the second light source3in various directions, two or more kinds of inclined planes are preferably formed in the optical waveguide1. In other words, first grooves20bare formed, as shown inFIG. 4A, and a second grooves20cis formed, as shown inFIG. 4B. The first grooves20band the second grooves20ccan be preferably formed in an approximately concentric shape, as shown inFIG. 1A. In this case, the first grooves20band the second grooves20ccan be formed in the front surface1C and the rear surface1D of the optical waveguide1, respectively.

In the first grooves20bshown inFIG. 4A, an effective gradient angle θ of an effective inclined plane22is set to 5° to 35°. Further, if the inclined light12emitted from the second light source3is incident on the effective inclined plane22, it is reflected in a direction away from the light source3. The reflected light14is refracted at the front surface1C of the optical waveguide1, and then emitted from the front surface1C at a near critical angle. If the emitted light is incident on the diffuser sheet4, it is converted into the diffused light18, which is distributed in a wide angular range β1from an optical axis19of the lighting device.

Furthermore, in the second grooves20C shown inFIG. 4B, an effective gradient angle θ of an effective inclined plane22is set to 50° to 70°. If inclined light12from the second light source3is totally reflected from the rear surface1D of the optical waveguide1and then incident on the effective inclined plane22, it is reflected in a direction that approaches the light source3. The reflected light14is refracted at the front surface1C of the optical waveguide1and then emitted from the front surface1C at a near critical angle. If the emitted light is incident on the diffuser sheet4, it is converted into diffused light18, which is distributed in a wide angular range β2from the optical axis19of the lighting device.

As such, if the first grooves20band the second grooves20care formed in the optical waveguide1, the diffused light18is distributed in a wide angular range β1 +β2 around the optical axis of the lighting device. Further, by allowing the diffused light18to be incident on the liquid crystal panel100shown inFIG. 1B, image display having a wide viewing angle can be realized.

As described above in detail, in the lighting device according to the embodiment, the plurality of inclined planes for reflecting light from the light sources and then allowing the light to be emitted from the front surface of the optical waveguide at different exit angles are provided, and each of the light sources is independently driven. Through this configuration, since each of the light sources is independently driven, the exit angle of emitted light can be changed. Further, by allowing emitted light to be incident on the liquid crystal panel, the viewing angle can be varied.

Furthermore, the first and second light sources2and3can be turned on at the same time. In this case, a narrow viewing angle range can be illuminated by the first light source2for a narrow viewing angle and the second light source3for a wide viewing angle, and a wide viewing angle range can be illuminated only by the second light source3for a wide viewing angle. Thereby, comparatively speaking, the narrow viewing angle range becomes bright and the wide viewing angle range becomes dark. Further, if the brightness to that extent is not needed in the narrow viewing angle range, the amount of light emitted from the first light source2for the narrow viewing angle can be controlled. More particularly, the amount of emitted light can be adjusted by controlling the driving signal of the second light source, or by adding electrical resistance. Furthermore, in the same manner, the amount of emitted light of the second light source3for the wide viewing angle can be controlled.

Second Embodiment

FIG. 5is an explanatory diagram illustrating a lighting device according to a second embodiment of the invention. The lighting device of the second embodiment is different from that of the first embodiment in which the diffuser sheet is disposed on the front surface1C of the optical waveguide1, in that a prism sheet6having indentations and protrusions is disposed at a side opposite to the front surface1C of the optical waveguide1. Furthermore, the shape of grooves formed in the optical waveguide1is different from those of the first embodiment. Moreover, the same reference numerals indicate the same components as those of the first embodiment, and detailed description thereof will be omitted.

In the second embodiment, the prism sheet6is disposed on the front surface1C of the optical waveguide1, as shown inFIG. 5. The prism sheet6includes a plurality of prisms7having a tripod pillar shape or a square pillar shape, which are formed by using a light-transmissive material. The vertex of each prism7is oriented toward a light-incident side (toward the optical waveguide1). A vertex angle φ of each prism7can be set to 55° to 70°, preferably 63° to 68°. The prism sheet6having these prisms7can be easily obtained at low cost.

Further, the rear surface1D of the optical waveguide1can be parallel to the liquid crystal panel100, or can be inclined against the liquid crystal panel100so that it can efficiently reflect the light emitted from the light source2toward the liquid crystal panel100.

FIGS. 6A and 6Bare explanatory diagrams illustrating the shape of grooves and the light reflection. The above-mentioned prism sheet has a property of converting light having a wide exit angle, which is emitted from the optical waveguide1, into light having a small exit angle, which is emitted from the prism sheet6, and converting light having a small exit angle, which is emitted from the optical waveguide1, into light having a wide exit angle, which is emitted from the prism sheet6. In the second embodiment, therefore, while light from the first light source2is emitted from the optical waveguide1at a wide exit angle, the light from the second light source3can be emitted from the optical waveguide1at a small exit angle. In this respect, effective inclined planes having different effective gradient angles are respectively disposed in the grooves20afor reflecting light from the first light source2, and in the grooves20bfor reflecting light from the second light source3.

FIG. 6Ais an explanatory diagram illustrating the shape of grooves20acorresponding to the first light source2, and the light reflection by the grooves20a. The plurality of the grooves20ahaving almost the same sectional shape is consecutively formed in a rear surface1D of an optical waveguide1. An effective gradient angle θ of an effective inclined plane22in the grooves20ais set to 0.5° to 5°, preferably about 2°.

Furthermore, if inclined light12remitted from the light source2is incident on an effective inclined plane22rin the first groove20a, it is converted into reflected light14rhaving an exit angle smaller than the incidence angle. If the exit angle does not exceed a critical angle in the surface of the optical waveguide1, the reflected light14ris totally reflected from the front surface1C of the optical waveguide1. If reflected light12sis incident on the effective inclined plane22in the second grooves20a, it is converted into reflected light14s having an exit angle smaller than the incidence angle. As such, as the light from the light source2is repeatedly reflected from the effective inclined plane22of the grooves20aand is repeatedly and totally reflected from the front surface1C of the optical waveguide1, it is converted into a reflected light14sof which an angle with respect to the normal direction of the optical waveguide1becomes larger than a critical angle in the surface of the optical waveguide1. The reflected light14sis emitted from the surface1C of the optical waveguide1at a near critical angle.

If such an emitted light15is incident on the prism7from one oblique side thereof, it is totally reflected toward the other oblique side, and then converted into emitted light18approximately parallel to the optical axis of the lighting device. Further, by allowing the emitted light18to be incident on the liquid crystal panel100shown inFIG. 5, image display having a narrow viewing angle can be realized.

FIG. 6Bis an explanatory diagram illustrating the shape of grooves20bcorresponding to the second light source3and the light reflection by the grooves20b. The grooves20b, including effective inclined planes22having an effective gradient angle θ of 20° to 50°, are formed in the rear surface1D of the optical waveguide1.

Furthermore, if inclined light12emitted from the light source3is incident on the effective inclined plane22in the grooves20b, it is converted into reflected light14approximately parallel to the normal direction of the optical waveguide1. If the reflected light14is emitted from the optical waveguide1and then incident on the prism7, it is refracted at one oblique side and a bottom side of the prism7and then converted into emitted light18ahaving an exit angle β1. Further, if emitted light from the optical waveguide1is incident on the prism7from the other oblique side of the prism7, it is converted into an emitted light18bhaving an exit angle β2, which is symmetrical to the emitted light18awith respect to the optical axis of the lighting device. Thereby, the emitted light18aand18bis distributed in a wide angular range of β1+β2 with respect to the optical axis of the lighting device. Further, by allowing the emitted light18aand18bto be incident on the liquid crystal panel100shown inFIG. 5, image display having a wide viewing angle can be realized. More particularly, if the first and second light sources2and3are turned on at the same time, image display can be realized over the entire range of the narrow viewing angle and the wide viewing angle.

Even in the lighting device that has been described above in detail according to the second embodiment, the exit angle of the emitted light can be changed in the same manner as in the first embodiment. Furthermore, by allowing the emitted light to be incident on the liquid crystal panel, the viewing angle can be varied.

FIG. 7is an explanatory diagram illustrating a modified example of a lighting device according to the second embodiment of the invention. The modified example of the lighting device according to the second embodiment is different from the first embodiment in which only the diffuser sheet4is disposed and the second embodiment in which only the prism sheet6is disposed, in that the prism sheet6and the diffuser sheet4are sequentially disposed on the front surface1C of the optical waveguide1. Even in this case, in the same manner as the second embodiment shown inFIG. 6, the grooves20acorresponding to the first light source2and the grooves20bcorresponding to the second light source3can be preferably formed in the optical waveguide1. Thereby, not only image display having a narrow viewing angle can be realized by the light emitted from the first light source, but also image display having a wide viewing angle can be realized by the light emitted from the second light source.

Liquid Crystal Display Device

Next, a liquid crystal display device in which a liquid crystal panel is provided at a light emitting side of the lighting device in each of the embodiments will be described with reference toFIGS. 8 and 9.

FIG. 8is an exploded perspective view illustrating a configuration of the liquid crystal panel.FIG. 9is a lateral cross-sectional view of the liquid crystal panel taken along line P-P ofFIG. 8. Referring toFIG. 9, a liquid crystal panel90has a liquid crystal layer92interposed between a lower substrate70and an upper substrate80. The liquid crystal layer92can be formed by using nematic liquid crystals, and the like. Further, twisted nematic (TN) mode can be adopted as the operating mode of the liquid crystal layer92. It is, however, to be noted that liquid crystal materials other than the nematic liquid crystal material can be used, and operating modes other than the twisted nematic (TN) mode can be adopted. Furthermore, an active matrix type liquid crystal panel using a TFD element as a switching element will be below described as an example. However, a liquid crystal panel of an active matrix type or a passive matrix type using other switching element can be used.

In the liquid crystal panel90, the lower substrate70and the upper substrate80, which are made of a transparent material such as glass, are disposed opposite to each other, as shown inFIG. 8.

A plurality of data lines81are formed within the upper substrate80. A plurality of pixel electrodes82, which are made of a transparent conductive material such as ITO, is arranged adjacent to the data lines81in a matrix. Further, a pixel region is constituted by a region where each pixel electrode82is formed. The pixel electrodes82are connected to the data lines81through TFD elements83. Each of the TFD elements83includes a first conductive film mainly composed of Ta and formed on the substrate, an insulating film mainly composed of Ta2O3and formed on the first conductive film, and second conductive films mainly composed of Cr and formed on the insulating film (so-called MIM structure). Furthermore, the first conductive films are connected to the data lines81, and the second conductive film are connected to the pixel electrodes82. Thereby, the TFD elements83serve as a switching element that controls the charging of the pixel electrodes82.

Meanwhile, color filter films76are formed on the lower substrate70. Each of the color filter films76includes color filters76R,76G and76B having an approximately rectangular shape in plan view. The color filters76R,76G and76B are formed by using pigments which transmit only different colors, respectively and are disposed in a matrix corresponding to the respective pixel regions. Further, a light-shielding film77for preventing the light leakage in neighboring pixel regions is formed at the peripheral region of the color filters. The light-shielding film77can be formed in a form of frame by using black chrome having a light-absorbing property. Furthermore, a transparent insulating film79for covering the color filter film76and the light-shielding film77is also formed.

A plurality of scanning lines72is formed on the insulating film79. The scanning lines72is formed in a form of approximately strip using a transparent conductive material such as ITO, and extends in a direction intersecting the data lines81of the upper substrate80. Further, the scanning lines72are formed to cover the color filters76R,76G and76B, which are arranged in their extending directions, and thus serve as opposite electrodes. Moreover, if a scanning signal is applied to the scanning lines72and a data signal is applied to the data lines81, electric field is applied to the liquid crystal layer by the pixel electrodes82and the opposite electrodes72, which are disposed opposite to each other.

Furthermore, as shown inFIG. 9, alignment films74and84are formed to cover the pixel electrodes82and the opposite electrodes72. The alignment films74and84serve to control the alignment state of liquid crystal molecules when electric field is not applied, and are formed by using polymer materials such as polyamides. A rubbing process is performed on the surface of the alignment films74and84. Thus, when no electric field is applied, a longer axis direction of the liquid crystal molecules near the surface of the alignment films74and84coincides with the direction of the rubbing process. The liquid crystal molecules are thus aligned substantially parallel to the alignment films74and84. Further, the rubbing process can be carried out on the alignment films74,84so that an alignment direction of liquid crystal molecules near the surface of the alignment films74and an alignment direction of liquid crystal molecules near the surface of the alignment films84are deviated only at a predetermined angle. Liquid crystal molecules constituting a liquid crystal layer92are thus stacked in a spiral direction along the thickness direction of the liquid crystal layer92.

Moreover, both the substrates70and80have their edge portions joined by a sealant93, which is made of a thermosetting or UV curable adhesive. Further, the liquid crystal layer92is sealed into a space surrounded by both the substrates70and80and the sealant93. The thickness (cell gap) of the liquid crystal layer92is defined by spacer particles95, which are disposed between the substrates.

Meanwhile, polarizing plates (not shown) are disposed outside the lower substrate70and the upper substrate80. The polarizing plates have their polarizing axes (transparent axes) deviated by a predetermined angle. Moreover, a lighting device (not shown) according to each of the embodiments is disposed as a backlight outside the light-incident side polarizing plate.

Furthermore, light incident from the backlight is converted into a straight polarized light in accordance with the polarizing axis of the light-incident side polarization plate, and then incident on the liquid crystal layer92from the lower substrate70. This straight polarized light is rotated by a predetermined angle along the twist direction of liquid crystal molecules, while transmitting through the liquid crystal layer92to which no electric field is applied, and then transmits the light-emitting side polarization plate. Thus, when no electric field is applied, white display is performed (normally-white mode). Meanwhile, if electric field is applied to the liquid crystal layer92, the liquid crystal molecules are realigned vertically to the alignment films74and84along the direction of the electric field. In this case, since the straight polarized light incident on the liquid crystal layer92is not rotated, it does not transmit the light-emitting side polarization plate. Thereby, when no electric field is applied, white display is performed. Furthermore, a gray level display can be performed depending on the intensity of an applied electric field.

The liquid crystal display device90is constructed as described above.

Electronic Apparatus

FIG. 10is a perspective view illustrating an example of a mobile phone according to the invention. The mobile phone1300shown inFIG. 10includes the above-mentioned liquid crystal display device as a small-sized display unit1301, a plurality of manual operation buttons1302, an earpiece1303, and a mouse piece1304.

The use of the above-mentioned liquid crystal display device is not limited to the mobile phone, but includes image display unit of portable electronic apparatuses such as e-books, personal computers, digital still cameras, liquid crystal TVs, view finder type or monitor direct-view-type video tape recorders, pagers, digital diaries, calculators, word processors, video telephones and touch panels. In either case, an electronic apparatus having a variable viewing angle can be provided.

It is also to be understood that the technical scope of the invention is not limited to the above-described embodiments, and various modifications can be made to the respective embodiments without departing from the scope and spirit of this invention. That is, the material, configuration, etc. in each of the embodiments are only illustrative, but can be properly changed.