Liquid crystal display device

A liquid crystal display (LCD) device including upper and lower substrates facing each other with a liquid crystal layer interposed therebetween, upper and lower polarization plates positioned on outer surfaces of the upper and lower substrates, respectively, and a beam steering film positioned on the upper polarization plate and including a plurality of curved-lenses formed on a surface of the beam steering film facing the upper polarization plate.

This application claims the benefit of Korean Patent Application No. 10-2006-0060342, filed on Jun. 30, 2006, which is hereby incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having a multi-domain structure implemented with a beam steering film.

2. Discussion of the Related Art

Research has been conducted on various planar panel display devices such as a liquid crystal display (LCD) device, a plasma display panel (PDP), an electroluminescent display device (ELD) and a vacuum fluorescent display device (VFD). Of these devices, the LCD device is used mostly in mobile image display devices such as a notebook computer, because the LCD device has excellent image quality characteristics, is light weight and compact, and has low power consumption characteristics. In addition, the LCD device is also used as a TV monitor or Computer monitor.

In addition, the LCD device displays an image by adjusting the birefringence of a liquid crystal layer interposed between two polarization plates, and by changing the transmittance according to the birefringence. Further, the LCD device is designed to provide an optimal condition with respect to light transmitted in a normal direction of a screen. Thus, the LCD device does not provide an optimal viewing condition when looking at the LCD device from a skewed viewing angle.

In addition, commercialized LCD modes including a twisted nematic (TN) mode, an in-plane switching (IPS) mode, a multi-domain vertical alignment (MVA) mode, an optically compensated bend (OCB) mode, a fringe-field switching (FFS) mode and an electrically controlled birefringence (ECB) mode use rod-like liquid crystals. However, the viewing condition at an angle is even worse for rod-like crystals because of an asymmetry of the birefringence. The poor viewing condition includes a deterioration in contrast and luminance, a color shift, a gray inversion phenomenon, etc.

Turning now toFIGS. 1A and 1B, which are overviews illustrating a concept of the above-mentioned TN mode. As shown inFIG. 1A, the liquid crystals in the TN mode are maintained horizontal to an alignment layer when the power is turned off. Then, as shown inFIG. 1B, when the power is turned on, the liquid crystals around the center of the liquid crystal layer are aligned vertical to the alignment layer in response to an electric field. In addition, a TFT LCD device includes a normally white mode, which is a display mode using an Off-state as white and an On-state as black.

Also, even though the LCD is advantageous because it has a high transmittance and is easy to produce, the TN mode is disadvantageous because of the gray inversion phenomenon that occurs at upper and lower viewing angles. In more detail, the gray inversion phenomenon is a phenomenon where an image looks brighter at a darker gray scale than at a brighter gray scale. In the TN mode, the gray inversion phenomenon makes an image look bright at an upper viewing angle and look dark at a lower viewing angle.

Further, the gray inversion phenomenon is worse at a lower viewing angle, which deteriorates a screen quality of the TN mode LCD and also limits the utility of the TN mode LCD.FIG. 2is a graph illustrating the gray inversion phenomenon according to upper and lower viewing angles of the TN mode LCD device. Also, the most significant cause of the gray inversion phenomenon is a variation in refractivity according to the viewing angles.

In more detail, and as shown inFIGS. 3A and 3B, the TN mode exhibits a small variation (dΔn⊥≈dΔn1≈dΔn2) of the refractivity according to the viewing angles in the Off-state, and a significant variation (dΔn⊥≠dΔn1≠dΔn2) of the refractivity according to the viewing angles in the On-state. The variation occurs because in the On-state an average director of the liquid crystals is slanted in the upper and lower directions, causing the light passing through the liquid crystals to experience an actual birefringence property (effective dΔn) which changes according to the viewing angles. Further, this phenomenon is more significant in the upper and lower directions.

In more detail, and as shown inFIG. 4, dΔn of a dark gray scale becomes greater than dΔn of a bright gray scale at a lower viewing angle below an apex where Δn of the average director of the liquid crystals theoretically becomes zero (0). Further, dΔn of the dark gray scale becomes greater than dΔn of the bright gray scale at an upper viewing angle above an apex where Δn of the average director theoretically becomes the maximum value. This phenomenon is exhibited as a gray inversion on a screen of a liquid crystal panel. In addition, the reference numerals30and31indicate upper and lower substrates, respectively, and the reference numeral40indicates a liquid crystal panel inFIGS. 3A to 4.

One method to overcome the gray inversion phenomenon is to dispose two or more domains of liquid crystals in a single pixel with a primary viewing angle of the liquid crystals of one domain being directed opposite to that of the liquid crystals of the other domain, thereby compensating the domains with each other. This method uses the counterbalancing asymmetry of the viewing angles so the asymmetric viewing angles are provided in opposite directions.

For example,FIGS. 5A,5B and6illustrate multiple domains in the TN mode LCD device. As shown inFIGS. 5A,5B and6, a user senses a mixed light passing through a first domain and a second domain. In other words, because the user senses an average value of dΔn of the first domain and dΔn of the second domain, it is possible to compensate the optical asymmetry. Further, the reference numerals50and51inFIGS. 5A,5B and6correspond to upper and lower substrates.

Thus, in the TN mode, a multi-domain including two domains in the upper and lower directions is mainly effective, because the asymmetry of the viewing angles occurs mainly in the upper and lower directions. Further, the asymmetry of the viewing angels and the gray inversion phenomenon are less in the right and left directions compared with the upper and lower directions because of a self compensation of the TN mode and a wide viewing angle in the right and left directions.

Further, as shown inFIG. 7, when using four domains (first to fourth domains) in upper, lower, right and left directions, one would expect to have an even more uniform improvement of the viewing angles in the four directions than the multi-domain effect in the right and left directions. However, the multi-domain has not been commercialized because a rubbing process must be performed differently for each domain. Furthermore, a wide view film used to widening the viewing angle cannot be applied to the TN mode.

In addition, the VA mode is used as a wide viewing angle mode to thereby solve the problem related to the viewing angle using the multi-domain. However, even in a four domain VA mode such as a multi-domain vertical alignment (MVA), a pattern-domain vertical alignment (PVA), etc, the viewing angle characteristic is not perfect. In particular,FIG. 8illustrates that for a VA mode LCD, the gray characteristics are changed according to the viewing angles such that a gray scale in the front side is different from a gray scale at a skewed angle.

A pixel division driving method (S-PVA) has been suggested to improve this problem, but the method still does not completely solve the problem. In addition, as shown inFIGS. 9A and 9B, the optical characteristics at a skewed angle are also significantly deteriorated compared to the front side in terms of luminance and contrast of the MVA.

In addition, the IPS mode and the FFS mode exhibit the best viewing angle characteristics among the modes used in commercialized LCD devices, and thus exhibit the least variation in optical characteristics according to the viewing angles. However, these modes still exhibit a deterioration in the luminance at the skewed angle. In particular, and as shown inFIGS. 10 and 11, the IPS mode uses a multi-domain to solve a color shift problem according to the viewing angles. The reference numerals100and110correspond to common electrodes, and the reference numerals101and111correspond to pixel electrodes inFIGS. 10 and 11. However, the multi-domain implemented in the IPS mode does not solve the problem of color shift in a black state. Rather, the IPS mode must use an expensive compensation film to solve this problem.

For example,FIG. 12shows a contrast of the IPS mode free from the compensation film according to the viewing angles. As shown, the optical characteristics are deteriorated at the skewed angle compared with those in the front side.

In summary, the related art liquid crystal display device has the following problems. The TN, VA and IPS modes have a deteriorated contrast and luminance, and a color shift and/or gray inversion phenomenon at skewed angles. Further, it is difficult to commercialize the method of using a multi-domain because of the complex production and costs related to the multi-domain method.

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to address the above-noted and other problems.

Another object of the present invention is to provide an LCD device using a multi-domain that is easy to produce and is less expensive.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the present invention provides in one aspect a liquid crystal display (LCD) device including upper and lower substrates facing each other with a liquid crystal layer interposed therebetween, upper and lower polarization plates positioned on outer surfaces of the upper and lower substrates, respectively, and a beam steering film positioned on the upper polarization plate and including a plurality of curved-lenses formed on a surface of the beam steering film facing the upper polarization plate.

In another aspect, the present invention provides a liquid crystal display (LCD) device including upper and lower substrates facing each other with a liquid crystal layer interposed therebetween, upper and lower polarization plates positioned on outer surfaces of the upper and lower substrates, respectively, and a beam steering film positioned on the upper polarization plate and including a plurality of curved-lenses independently formed on a surface facing the upper polarization plate.

DETAILED DESCRIPTION OF THE INVENTION

Turning first toFIG. 13, which is an overview illustrating an LCD device including a beam steering film according to one embodiment of the present invention. As shown, the LCD device includes upper and lower substrates130and131, a liquid crystal layer135filled with liquid crystals between the upper and lower substrates130and131, upper and lower polarization plates132and133positioned on outer surfaces of the upper and lower substrates130and131, respectively, and a beam steering film134positioned on the upper polarization plate132to permit implementation of a multi-domain by controlling light.

In more detail, the beam steering film134is provided to accomplish a cross-compensation effect in the multi-domain while maintaining a single direction of primary viewing angles of liquid crystals within a liquid crystal cell so as not to have two or more directions of the primary viewing angles.

Next,FIG. 14is an overview schematically showing a TN mode LCD device having the beam steering film134according to an embodiment of the present invention. As shown, the TN mode LCD device includes a liquid crystal cell140having upper and lower substrates with liquid crystals filled therebetween, first and second wide view films141and144respectively positioned on upper and lower surfaces of the liquid crystal cell140, upper and lower polarization plates142and145respectively positioned on upper and lower surfaces of the first and second wide view films141and144, a backlight unit146positioned below the lower polarization plate145to act as a light source, and a beam steering film143positioned on the upper polarization plate142to permit implementation of a multi-domain by controlling light.

Here, the directional arrows shown on the upper and lower surfaces of the liquid crystal cell140inFIG. 14indicate a rubbing direction. In addition, the beam steering film is positioned on the uppermost surface of an LCD panel to achieve a cross-compensation effect as in the multi-domain while maintaining a single direction of primary viewing angles of liquid crystals within a liquid crystal cell so as not to have two or more directions of the primary viewing angle.

As shown inFIG. 15, the beam steering film serves to mix light after forcibly changing paths of the light propagating through the liquid crystal cell. Thus, according to an embodiment of the present invention, the LCD device accomplishes the multi-domain effect using the beam steering film143. That is, the beam steering film is effective in mixing light propagating in the upper and lower directions in the TN mode LCD device. Further, the reference numerals150,151and152inFIG. 15correspond to upper and lower substrates, and a liquid crystal layer, respectively.

Embodiments of a beam steering film of the present invention positioned the uppermost surface of the LCD device will now be described.

First,FIGS. 16 and 17is are overviews illustrating an LCD device including a beam steering film according to the first embodiment. Referring toFIGS. 16 and 17, the LCD device includes the upper and lower substrates130and131facing each other with the liquid crystal layer135interposed therebetween, the upper and lower polarization plates132and133positioned on the outer surfaces of the upper and lower substrates130and131, respectively, and the beam steering film134positioned on the upper polarization plate132. As shown, the beam steering film134includes a plurality of curved-lenses formed on a surface facing the upper polarization plate.

In addition, as shown inFIGS. 16 and 17, the beam steering film134includes a planar supporting part134aand a ridged part134bhaving a plurality of curved-lenses. Further, the supporting part134amay be integrally formed with the ridged part134b. As shown, each of the curved-lens of the ridged part134bhas a convex shape, an equal width and is arranged in one direction.

Further, the supporting part134aand the ridged part134binclude at least one of polymethylmethacrylate (PMMA), vinyl chloride, acrylic resins, polycarbonate (PC), polyethylene therephtalate (PET), polyethylene (PE), polystyrene (PS), polypropylene (PP), polyimide (PI) resins, glass and silica, or combination thereof. In addition, when the supporting part134aand the ridged part134bare formed as an integral component, the integral component may formed of the at least one or combination of the materials described above. In addition, these materials for the beam steering film134can also be applied to the second to sixth embodiments of the present invention.

Further, the ridged part134bis spaced a predetermined distance from the upper polarization plate132. Although not shown in the drawings, both sides of the beam steering film134are fixed by a fixing frame or other fixing mechanism to prevent the beam steering film134from contacting the upper polarization film132. Further, each of the curved-lenses preferably has a width of about 300 μm or less for 100 ppi. In addition, as the width of each unit curved-lenses is decreased, it is more effective. Also, each curved-lens has a width not more than a length of a major axis of the LCD device.

Turning next toFIGS. 18A and 18B, which illustrate an optical path conversion effect resulting from the refraction of the convex lenses, and a pseudo-multi domain effect resulting from a scattering thereof, respectively. Thus, using the beam steering film134in the LCD device according to the first embodiment, a user can view an image with a uniform luminance in all directions.

Further,FIG. 18Cillustrates how an angle by which light passes through the beam steering film134is bent according to Snell's law. Specifically, the angle is determined by an incident angle Θa of light incident on the film134, a refractive index n of the film134, and a refractive index n′ of an incident layer contacting the ridged part of the film134. The incident angle Θa of light is defined as an angle of incident light with respect to a tangential plane of an incident surface. The angle by which the light passes through the beam steering film134is bent is expressed by Equation 1:

sin=nn′⁢sin⁡(θ⁢⁢a-sin-1⁡(nn′⁢sin⁢⁢θ⁢⁢a))where the incident layer is air.

Next, with reference toFIGS. 19A to 33, the LCD device of the present invention including the beam steering film according to the first embodiment will be compared with a related art TN mode LCD device in terms of the viewing angle, the contrast ratio and a visual sensation in white and black states.

First, as shown inFIGS. 19A and 19B, the LCD device including the beam steering film of the present invention exhibits improved characteristics in terms of upper and lower viewing angles compared with those of the related art TN mode LCD device in the white state. In addition, as shown inFIGS. 20A and 20B, the LCD device including the beam steering film of the present invention exhibits a wide distribution of black compared with that of the related art TN mode LCD device in the black state.

Furthermore, as shownFIGS. 21A and 21B, the LCD device including the beam steering film of the present invention exhibits improved characteristics in terms of the contrast ratio at upper and lower portions thereof compared with those of the related art TN mode LCD device. In addition, as shown inFIG. 22, the related art TN mode LCD device exhibits a negative visual sensation at upper, lower, right and left portions thereof due to the occurrence of the gray inversion, whereas the LCD device including the beam steering film of the present invention is free from the gray inversion at the upper, lower, right and left portions thereof. Thus, the LCD device including the beam steering film of the present invention exhibits an improved visual sensation compared to the related art TN mode LCD device.

In addition,FIGS. 23A and 23Billustrate a comparison between the LCD device including the beam steering film and the related art TN mode LCD regarding upper and lower gray-scales. First, as shown inFIG. 23A, when showing gray scales of 9 stages from black to white for the related art TN mode LCD device for the upper and lower viewing angles, the gray inversion and gray conglomeration begin to occur at about 15 degrees of the lower viewing angle, and the gray inversion of the brightest gray scale begins to occur at about 20 degrees of the upper viewing angle. Here, “G0” indicates black, and “G8” indicates white.

As described above, a color conglomeration phenomenon at the upper and lower viewing angles occurs. In particular, a more severe color conglomeration phenomenon occurring at the lower viewing angle than at the upper viewing angle causes the gray inversion phenomenon, thereby providing a negative gray characteristic to the related art TN mode LCD device. In addition, the related art TN mode LCD device exhibits an negative uniformity in an overall luminance due to a significant difference in the luminance between a viewing angle at a central region thereof and an upper or lower viewing angle.

In contrast, and as shown inFIG. 23B, the LCD including the beam steering film of the present invention is free from the gray inversion phenomenon at the upper and lower viewing angles, and exhibits positive uniformity in overall luminance due to a negligible difference in the luminance between a viewing angle at a central region thereof and an upper or lower viewing angle.

Next, the LCD device including the beam steering film according to the second to fourteenth embodiments of the present invention will be described. Further, the LCD device according to the second to fourteenth embodiments have the same construction as the LCD device shown inFIG. 16excluding the beam steering film. Hence, a redundant description will be omitted, and the same components will be denoted by the same reference numerals.

First, referring toFIG. 24, a beam steering film240according to the second embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film240includes a plurality of curved-lenses formed on one surface facing the upper polarization plate132, and a plurality of slits241formed on the other surface and corresponding to borders between the curved-lenses to shield or reflect light.

Specifically, the beam steering film240includes the planar supporting part134aand the ridged part134bhaving the plurality of curved-lenses. The film240also includes the plurality of slits241arranged in one direction on an upper surface of the supporting part134aand corresponding to the borders between the curved-lens shapes of the ridged part134b. Further, the supporting part134amay be integrally formed with the ridged part134b.

In addition, each of the curved-lens of the ridged part134bhas a convex shape, an equal width and is arranged in one direction. Alternatively, the curved-lenses may have different widths. Further, the ridged part134bis spaced a predetermined distance from the upper polarization plate132. Although not shown in the drawings, both sides of the beam steering film240are fixed by a fixing frame or other fixing mechanisms to prevent the beam steering film240from contacting the upper polarization film132.

Also, each of the curved-lenses preferably has a width of about 300 μm or less for 100 ppi. In addition, as the width of each of the unit curved-lenses is decreased, the lens is more effective. In addition, each curved-lens has a width of not more than a length of a major axis of the LCD device. Further, a width of the slit241is preferably less than 100% of a width of opening region of one pixel.

Therefore, as shown inFIG. 25, when the beam steering film is provided with the slits241capable of shielding or reflecting light as described above, the LCD device is further improved in gray characteristics at the upper and lower viewing angles, and thus has a more uniform luminance.

The beam steering films according to the third to fifth embodiments of the present invention overcome a deterioration in luminance in the front side of a LCD device. First, referring toFIG. 26, a beam steering film260according to the third embodiment is positioned on the upper polarization plate132(seeFIG. 16).

The beam steering film260includes a plurality of curved-lenses formed on one surface facing the upper polarization plate132, and is planar between the curved-lenses. Specifically, the beam steering film260includes the supporting part134ahaving a predetermined thickness, and the ridged part134bhaving the plurality of curved-lenses spaced a predetermined distance from each other and being arranged in one direction on a lower surface of the supporting part134awith a planar section formed between the curved-lenses.

The supporting part134amay be integrally formed with the ridged part134b. Further, the planar section between the curved-lenses of the ridged part134bimproves the luminance in the front side of the LCD device, because the light propagates straightly without being bent on this section.

Next, referring toFIG. 27, a beam steering film270according to the fourth embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film270includes a plurality of curved-lenses formed on one surface of the beam steering film270facing the upper polarization plate132, in which each curved-lens has a flat central region. Specifically, the beam steering film270includes the supporting part134ahaving a predetermined thickness, and the ridged part134bhaving the plurality of curved-lenses arranged in one direction on a lower surface of the supporting part134a, where each curved-lens of the ridged part134bhas the flat central region.

In addition, each curved-lens of the ridged part134bhas a convex lens shape, and the supporting part134amay be integrally formed with the ridged part134b. The flat regions improve the luminance in the front side of the LCD device because the light propagates straightly without being bent on these regions.

Next, referring toFIG. 28, a beam steering film280according to the fifth embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film280includes a plurality of curved-lenses formed on one surface of the beam steering film280facing the upper polarization plate132, and a plurality of concave lenses281, each of which is formed between the curved-lenses.

Specifically, the beam steering film280includes the supporting part134ahaving a predetermined thickness, and the ridged part134bhaving a plurality of curved-lenses arranged in one direction on a lower surface thereof. Further, the plurality of curved-lenses of the ridged part134binclude a plurality of convex lenses and plurality of concave lenses, each of which is formed between the convex lenses. Also, the supporting part134amay be integrally formed with the ridged part134b. Further, when a concave lens is formed in each space between the convex lenses of the ridged part134b, the concave lenses improve the luminance in the front side of the LCD device.

Next, the beam steering films according to the sixth to ninth embodiments of the present invention overcome the Moire phenomenon of light. Referring toFIG. 29, a beam steering film290according to the sixth embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film290includes the plurality of curved-lenses formed on one surface facing the upper polarization plate132, and a scattering layer291formed on the other surface.

Specifically, the beam steering film290includes the planar supporting part134a, the ridged part134bhaving the plurality of curved-lenses, and the scattering layer291formed on an upper surface of the supporting part134ato provide a Haze property. The supporting part134amay be integrally formed with the ridged part134b. In addition, each of the curved-lenses has a convex shape and is arranged in one direction. Thus, with the scattering layer291for the Haze property formed on the upper surface of the beam steering film290as described above, it is possible to overcome the Moire phenomenon of light.

Next, referring toFIG. 30, a beam steering film300according to the seventh embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film300includes a plurality of curved-lenses randomly arranged on one surface facing the upper polarization plate132. Specifically, the beam steering film300includes a plurality of randomly arranged supporting parts134a, and a plurality of ridged parts134brespectively formed on lower surfaces of the supporting parts134a, where each of the ridged parts134bhas the plurality of curved-lens. The supporting part134amay be separately or integrally formed with the ridged part134b. In addition, each of the curved-lenses of the ridged part134bhas a convex shape.

Further, although the ridged part of the beam steering film300is shown facing upwardly inFIG. 30, the ridged part is configured to face the upper polarization plate (seeFIG. 16). Thus, when the curved-lenses of the beam steering film300are randomly arranged instead of being arranged linearly, it is possible to overcome the Moire phenomenon of light.

Next, referring toFIG. 31, a beam steering film310according to the eighth embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film300includes a plurality of wavy curved-lenses formed on one surface facing the upper polarization plate132. Specifically, the beam steering film310includes the planar supporting part134a, and the ridged part134bhaving the plurality of wavy curved-lenses formed on a lower surface of the supporting part134a, where each of the wavy curved-lens shapes of the ridged part134bhas a variable thickness.

Further, the supporting part134amay be integrally formed with the ridged part134b. In addition, the curved-lenses of the ridged part134bhave an equal width and are arranged in one direction. Also, each of the curved-lenses of the ridged part134bhas a convex shape.

Although the ridged part134bof the beam steering film310is shown facing upwardly inFIG. 31, the ridged part is configured to face the upper polarization plate (seeFIG. 16). In addition, when the ridged part134bis formed in the wavy shape as described above, it is possible to overcome the Moire phenomenon of light.

Next, referring toFIG. 32, a beam steering film320according to the ninth embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film320includes a plurality of curved-lenses formed on one surface facing the upper polarization plate132. Specifically, the beam steering film310includes the planar supporting part134a, and the ridged part134bincluding the plurality of curved-lenses formed on a lower surface of the supporting part134a, where adjacent curved-lenses of the ridged part134bhave different thicknesses and widths. In other words, two or more lens units of the ridges part134bhave different widths and thicknesses.

Further, the supporting part134amay be integrally formed with the ridged part134b. In addition, each curved-lens of the ridged part134bhas a convex shape and are arranged in one direction. When the adjacent curved-lenses of the ridged part134bare formed to have different thicknesses and widths as described above, it is possible to overcome the Moire phenomenon of light.

A beam steering film according to the tenth embodiment of the present invention overcomes an intermediate gray scale asymmetry in a TN mode LCD device. Referring toFIGS. 33A and 33B, the LCD device includes the upper and lower substrates130and131facing each other with the liquid crystal layer135interposed therebetween, the upper and lower polarization plates132and133positioned on outer surfaces of the upper and lower substrates130and131, respectively, and the beam steering film134positioned on the upper polarization plate132. Further, the beam steering film134includes a plurality of curved-lenses formed on one surface of the beam steering film134facing the upper polarization plate132.

In addition, the beam steering film134includes the planar supporting part134aand the ridged part134bhaving the plurality of curved-lenses formed on the supporting part134a. The supporting part134amay be integrally formed with the ridged part134b. Further, each curved-lens of the ridged part134bhas a convex shape and is arranged in one direction. Also, to improve a lower viewing angle by bending light downwardly, each convex lens of the ridged part134bis asymmetrically formed such that the convex lens is further slanted toward one side of a lower portion thereof.

The LCD device according to the tenth embodiment is constructed similar to the first embodiment. In addition, note that in the first to tenth embodiments excluding the seventh embodiment, the curved-lenses of the ridged part of the beam steering film are arranged in one direction.

The beam steering films according to eleventh to sixteenth embodiments of the present invention also include ridged parts to implement a multi-domain of four domains. The LCD devices including the beam steering films according to the eleventh to sixteenth embodiments also have the same construction as the LCD device shown inFIG. 16excluding the beam steering film. Hence, a redundant description will be omitted, and the same components will be denoted by the same reference numerals herein.

First, referring toFIGS. 34A and 34B, a beam steering film340according to the eleventh embodiment provides a multi-domain effect of four domains. The beam steering film340includes the planar supporting part340a, and the ridged part340bhaving a plurality of curved-lenses spaced from each other on the supporting part340a. Further, the supporting part340amay be integrally formed with the ridged part340b. In other words, the curved-lenses of the ridged part340bare not arranged in one direction, but separately formed.

In addition, each curved-lens of the ridged part340bhas a convexly semispherical or dome shape in an opposite direction to a light emitting side, and has a predetermined size. Although the semispherical shape of the curved-lens is most effective, the ridged part340bmay be formed as an array of lenses, each of which has a pyramid shape or a Euclidean geometry. Further, as described above in the first embodiment, the ridged part340bof the beam steering film340is spaced a predetermined distance from the upper polarization plate132(seeFIG. 16).

In other words, although not shown in the drawings, both sides of the beam steering film340are fixed by a fixing frame or other fixing mechanisms to prevent the beam steering film340from contacting the upper polarization film132. Also, each curved-lens has a width of about 300 μm or less for 100 ppi. In addition, as the width is decreased, the lens is more effective. Here, each curved-lens has a width of not more than a length of a major axis of the LCD device.

Referring toFIGS. 35A and 35B, a beam steering film340according to the twelfth embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film340includes a plurality of curved-lenses formed on one surface facing the upper polarization plate132, and a plurality of slits350cformed on the other surface thereof corresponding to each border between the curved-lenses to shield or reflect light.

Specifically, the beam steering film350includes a planar supporting part350a, a ridged part350bhaving the plurality of curved-lenses formed on a lower surface of the supporting part350a, and a plurality of slits350cformed on an upper surface of the supporting part340aalong each border between the curved-lenses of the ridged part350b. In other words, the plural slits350care formed along each border between the curved-lenses of the ridged part350b.

Also, the supporting part350amay be integrally formed with the ridged part350b. In addition, each curved-lens of the ridged part350bhas a convexly semispherical or dome shape in an opposite direction to a light emitting side, and has a predetermined size. The curved-lenses may have different widths and may have a planar section or a concave section formed therebetween. Furthermore, each of the curved-lenses may have a flat region on a surface thereof.

Although the semispherical shape is most effective, the ridged part350bcan be formed as an array of lenses, each of which has a pyramid shape or a Euclidean geometry. In addition, a width of the slit350cis preferably less than 100% of a width of opening region of one pixel.

When the beam steering film further includes the slits350ccapable of shielding or reflecting light as described above, the LCD device can have further improved gray characteristics at the upper and lower viewing angles, and thus can have a more uniform luminance.

The beam steering films according to the thirteenth to fifteenth embodiments of the present invention overcome a luminance deterioration in the front side of an LCD device. First, referring toFIG. 36, a beam steering film360according to the thirteenth embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film360includes a plurality of curved-lenses formed on one surface facing the upper polarization plate132, and is planar between the curved-lenses.

Specifically, the beam steering film360includes a supporting part360ahaving a predetermined thickness, and a ridged part360bhaving the plurality of curved-lenses formed on a lower surface of the supporting part360awith a planar section formed between the curved-lens shapes. Each of the curved-lenses of the ridged part360bhas a convex lens shape.

Also, the supporting part360amay be integrally formed with the ridged part360b. When the beam steering film360is planar between the curved-lens shapes of the ridged part350bas described above, such a planar section improves the luminance in the front side of the LCD device because light propagates straightly without being bent on this section.

Next, referring toFIG. 37, a beam steering film370according to the fourteenth embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film370includes a plurality of curved-lenses formed on one surface facing the upper polarization plate132, where each of the curved-lenses has a flat central region. Specifically, the beam steering film370includes a supporting part370ahaving a predetermined thickness, and a ridged part370bhaving the plurality of curved-lenses formed on a lower surface of the supporting part370a, where each of the curved-lenses of the ridged part370bhas the flat central region.

In addition, each of the curved-lenses of the ridged part370bhas a convex lens shape. The supporting part370amay also be integrally formed with the ridged part370b. When flat regions are formed on the ridged part370bas described above, these regions improve the luminance in the front side of the LCD device because light propagates straightly without being bent on these regions.

Next, referring toFIG. 38, a beam steering film380according to the fifteenth embodiment is positioned on the upper polarization plate132(seeFIG. 16). The beam steering film380includes a plurality of curved-lenses formed on one surface facing the upper polarization plate132, and a plurality of concave lenses, each of which is formed between the curved-lenses.

Specifically, the beam steering film380includes a supporting part380ahaving a predetermined thickness, and a ridged part380bhaving the plurality of curved-lenses formed on a lower surface of the supporting part380a. Further, the plurality of curved-lenses of the ridged part380binclude a plurality of convex lenses and a plurality of concave lenses, each of which is formed between the convex lenses. The supporting part134amay also be integrally formed with the ridged part134b. Thus, when a concave lens is formed in each space between the convex lenses of the ridged part380b, the luminance in the front side of the LCD device is improved.

A beam steering film according to the sixteenth embodiment of the present invention overcome an intermediate gray scale asymmetry in a TN mode LCD device. Referring toFIGS. 39A and 39B, an LCD device including the beam steering film according to the sixteenth embodiment has upper and lower substrates130and131facing each other with a liquid crystal layer135interposed therebetween, upper and lower polarization plates132and133positioned on outer surfaces of the upper and lower substrates130and131, respectively, and a beam steering film390positioned on the upper polarization plate132.

The beam steering film390includes a plurality of asymmetrical curved-lenses formed on one surface of the beam steering film390to face the upper polarization plate132. Further, the beam steering film390includes a planar supporting part390aand a ridged part390bhaving the plurality of asymmetrical curved-lens formed on the supporting part390a. The supporting part390amay also be integrally formed with the ridged part390b.

In addition, each of the curved-lenses of the ridged part390bhas a convex shape. To improve a lower viewing angle by bending light downwardly, each convex lens of the ridged part134bis asymmetrically formed such that the convex lens is further slanted toward one side of a lower portion thereof.

The LCD device according to the present invention constructed as above has advantageous effects as follows. The LCD device is provided on an uppermost surface thereof with a beam steering film which has curved-lenses formed thereon, solving problems such as luminance deterioration, gray inversion, contrast deterioration, and color shift at upper and lower viewing angles.