KR101181952B1 - Lcd device with low color shift - Google Patents

Abstract

The color shift reduction liquid crystal display device includes a liquid crystal layer between the front polarization layer and the rear polarization layer, and a color shift reduction layer between the liquid crystal layer and the front polarization layer, wherein the color shift reduction layer is A coating film layer constituting a layer and a plurality of negative lens portion formed to be spaced apart from each other on the coating film layer, and due to the birefringence characteristics of the liquid crystal layer light emitted from the liquid crystal layer in a different color depending on the viewing angle and gray level Among them, the emission direction of the light incident on the lens unit is dispersed and mixed with the light passing between the lens units spaced apart from each other. The color shift reducing layer may be a front transparent substrate provided between the liquid crystal layer and the front polarizing layer, or may be provided between the front transparent substrate and the front polarizing layer of the liquid crystal display device.

Description

Color shift reduction liquid crystal display device {LCD DEVICE WITH LOW COLOR SHIFT}

The present invention relates to a liquid crystal display device, and more particularly, to a color shift reduction liquid crystal display device having a color shift reduction layer between the liquid crystal layer and the front polarizing layer.

As the modern society is highly informationized, image display-related components and devices have been remarkably advanced and widespread. Among them, display apparatuses for displaying images are widely used as television apparatuses, monitor apparatuses for personal computers, and the like, and are being enlarged and thinned.

In general, a liquid crystal display is a flat panel display that displays an image using liquid crystal, and is thinner and lighter than other display devices, and has a low driving voltage and low power consumption. It is widely used throughout the industry.

1 is a conceptual diagram conceptually showing the basic structure and driving principle of an LCD. For example, in the conventional VA mode LCD, the optical axes of the two polarization layers 110 and 120 are attached to be perpendicular to each other. The liquid crystal layer 150 exhibiting birefringence is positioned between two front transparent substrates 130 coated with the transparent electrode 140 and a rear transparent substrate 130. When the electric field is applied by the driving power supply unit 180, the liquid crystal molecules are arranged to move perpendicular to the electric field.

The light from the backlight unit is linearly polarized after passing through the rear polarizing layer 120. When the light is off, as shown in the left side of FIG. 1, since the liquid crystal is vertically aligned with respect to the transparent substrate, the linearly polarized light is in that state. Is maintained as it does not pass through the front polarizing layer 110 perpendicular to the rear polarizing layer (120).

On the other hand, in the on state, as shown on the right side of FIG. 1, the liquid crystal is horizontally oriented between the optical axes of the two orthogonal polarization layers 110 and 120 in a direction parallel to the transparent substrate by an electric field, and thus linearly polarized through the rear polarization layer. The light passes through the front polarizing layer by changing to a linearly polarized, circularly or elliptically polarized state in which the polarization state is rotated 90 degrees immediately before reaching the front polarizing layer while passing through the liquid crystal layer. By adjusting the intensity of the electric field, the alignment angle of the liquid crystal is gradually changed from the vertical alignment to the horizontal direction, and the intensity of light emitted from the liquid crystal can be adjusted.

2 is a conceptual diagram illustrating an alignment state and a light transmittance of a liquid crystal according to audiovisual.

When the liquid crystal molecules are arranged in a predetermined direction in the pixel 220, the arrangement state is different depending on the audiovisual.

When viewed from the left side of the front (210), the arrangement state of the liquid crystal molecules is almost seen in a horizontal orientation (212), the screen looks relatively bright. When viewed from the front of the screen 230, the arrangement state of the liquid crystal molecules 232 looks the same as the arrangement of liquid crystal molecules in the pixel 220. When viewed from the right side of the front (250), the arrangement state of the liquid crystal molecules is shown in the vertical alignment (252), the screen looks relatively dark.

Therefore, the LCD generates a change in intensity and color according to the audio-visual change, and the viewing angle is greatly limited compared to the self-luminous display. Therefore, much research has been conducted for improving the viewing angle.

3 is a conceptual diagram illustrating an example of the prior art for improving the contrast ratio change and color shift according to audiovisual.

Referring to FIG. 3, the pixel is divided into two partial pixels, that is, the first pixel portion 320 and the second pixel portion 340 so that the liquid crystal arrangement of each pixel portion is symmetrical to each other. According to the viewing direction, the arrangement of the liquid crystals in the first pixel unit 320 and the arrangement of the liquid crystals in the second pixel unit 340 are simultaneously seen, and the intensity of light visible to the viewer is determined by the light of each pixel unit. It is the sum of the strengths of.

That is, when viewed from the left side of the front side 310, the liquid crystal of the first pixel portion 320 is seen as the horizontal alignment 312 and the liquid crystal of the second pixel portion 340 is shown as the vertical alignment 314. The screen may be made bright by the one pixel unit 320. Similarly, when viewed from the right side of the front face 350, the liquid crystal of the first pixel portion 320 is shown in the vertical alignment 352, and the liquid crystal of the second pixel portion 340 is shown in the horizontal alignment 354. By the two pixel unit 340, the screen can be seen brightly. When viewed from the front (330) is the same as the arrangement state of each pixel portion. Accordingly, as the viewer sees, the brightness of the screen becomes the same or similar as the viewing angle changes, and is symmetric about the vertical direction with respect to the screen. Therefore, the contrast ratio change and the color change degree according to the audio-visual change can be improved.

4 is a conceptual diagram illustrating another example of the related art for improving the contrast ratio change and color shift according to audiovisual.

Referring to FIG. 4, an optical film 420 having a birefringence characteristic, the characteristic of which is the same as that of the liquid crystal molecules in the pixel 440 in the LCD panel, and which is symmetric with the arrangement state of the liquid crystal molecules, is added. Due to the arrangement state of the liquid crystal in the pixel 440 and the birefringence characteristic of the optical film 420 according to the viewing direction, the light intensity seen by the viewer is the sum of the light intensities.

That is, when viewed from the left side of the front (410), the liquid crystal in the pixel 440 is shown in the horizontal alignment 414 and the virtual liquid crystal by the optical film 420 is shown in the vertical alignment 412, the light intensity is Each sum. Similarly, when viewed from the right side of the front (450), the liquid crystal in the pixel 440 is shown in the vertical alignment 454 and the virtual liquid crystal by the optical film 420 is shown in the horizontal alignment 452, the light intensity is Each sum. In the front view 430, the arrangement state of the liquid crystal molecules in the pixel 440 and the arrangement state of the optical film 420 appear to be the same (432 and 434).

However, even with the above technique, there is still a problem that color shift occurs due to audiovisual and color change occurs as audiovisual increases.

In addition, in a conventional display device, particularly a TN mode liquid crystal display device, gamma curve distortion and gray level inversion occur.

An object of the present invention is to provide a liquid crystal display device that can improve the color shift phenomenon according to the increase in audio-visual.

Another object of the present invention is to provide an optical filter for a liquid crystal display device and a liquid crystal display device having the same, which can improve gamma curve distortion and gray level inversion.

In addition, an object of the present invention is to provide an optical filter for a liquid crystal display device and a liquid crystal display device having the same, which can improve the color shift phenomenon and improve the reduction of the contrast ratio through the suppression of haze generation and suppress the double phase.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the present invention is provided with a liquid crystal layer between the front polarizing layer and the rear polarizing layer, and provided with a color shift reducing layer between the liquid crystal layer and the front polarizing layer, the color shift The reducing layer includes a coating film layer forming a layer and a plurality of negative lens portions formed to be spaced apart from each other on the coating film layer, and the liquid crystal layer has a different color depending on the viewing angle and gray level due to the birefringence characteristics of the liquid crystal layer. A light shift reducing liquid crystal display device, characterized by dispersing the emission direction of the light incident on the lens unit and mixing with the light passing through the lens unit spaced apart from each other.

The color shift reducing layer may be a front transparent substrate.

The color shift reducing layer may be provided between the front transparent substrate and the front polarizing layer of the liquid crystal display device.

According to the above configuration, the present invention has the effect of securing the viewing angle of the display device and improving the image quality by minimizing the color shift phenomenon caused by the increase in the audiovisual angle.

In addition, the present invention has the effect of improving the gamma curve distortion and tone inversion.

In addition, the present invention suppresses the occurrence of double phase, has the effect of suppressing the generation of haze and improvement of the contrast ratio.

1 is a conceptual diagram conceptually showing the basic structure and driving principle of an LCD.
2 is a conceptual diagram illustrating an alignment state and a light transmittance of a liquid crystal according to audiovisual.
3 is a conceptual diagram illustrating an example of the prior art for improving the contrast ratio change and color shift according to audiovisual.
4 is a conceptual diagram illustrating another example of the related art for improving the contrast ratio change and color shift according to audiovisual.
5 to 7 are cross-sectional views illustrating a color shift reducing layer according to comparative embodiments.
8 is a view illustrating a method of manufacturing a color shift reducing layer according to a comparative example.
9 is a view showing a relationship between the depth / width ratio of the lens unit and the color shift improvement rate.
FIG. 10 is a diagram illustrating a relationship between a spacing / pitch ratio of lens sections and a color shift improvement ratio. FIG.
11 is a view showing the relationship between the spacing / pitch ratio and the transmittance of the lens portion.
12 to 17 are views showing the relationship between the shape of the cross section of the lens unit and the dual phase.
18 to 23 are views showing that the color shift reducing layer according to the comparative example is installed in close contact with the display panel, thereby suppressing the occurrence of double phase and haze.
24 to 27 are views showing color shift improvement, gray level inversion, and gamma curve distortion improvement by a color shift reduction layer of a comparative example in an LCD monitor (model name: B2440MH) employing a CCFL BLU and a TN panel.
28 to 31 are views showing improvement in color shift, gray level inversion, and gamma curve distortion by the color shift reduction layer of the comparative example in an LCD monitor (model name: BX2440) employing an LED BLU and a TN panel.
32 to 35 are views illustrating improvement in color shift and gamma curve distortion by the color shift reduction layer of the comparative example in a 46-inch LCD TV (Model: LH46CSPLBC) employing an S-PVA panel.
FIG. 36 is a view illustrating color change of an S-IPS mode LCD TV without the color shift reducing layer of the comparative example, and FIG. 37 displays the color shift reducing layer of the comparative example having self-adhesiveness on the LCD TV of FIG. It is attached to the panel and shows the result of measuring the color change improvement rate.
38 to 40 are diagrams showing the relationship between the size of the lens portion and the dual image generation, and FIG. 41 is a diagram showing the relationship between the size of the lens portion and moiré generation.
42 and 43 schematically illustrate color shift reducing optical filters according to embodiments of the present invention.

Comparative Example

Hereinafter, comparative examples will be described. Through the comparative example, the principle of color shift reduction of the color shift reduction layer will be described first. Subsequently, the method of suppressing the occurrence of the double phase and the haze caused by the color shift reduction layer will be described, and the color shift reduction layer will be described to be effective in improving the gamma curve distortion and gray level inversion.

5 and 6 are cross-sectional views showing a color shift reducing layer according to a comparative example.

The color shift reducing layer of FIG. 5 is provided in front of the display panel 10.

As shown, the color shift reduction layer 20 includes a coating film layer 21 and a lens unit 23.

The coating film layer 21 is formed of a layer of a material that transmits light. The coating film layer 21 may be formed of a transparent polymer resin, in particular an ultraviolet curable transparent resin.

The lens unit 23 is formed on the coating film layer 21 in an intaglio with a predetermined depth. The lens portion refracts light to improve color shift. The lens unit 23 reduces the color change as the audiovisual increases due to the color mixing effect. The width of the lens unit may be smaller than the distance between the lens units to transmit a large amount of light emitted in the normal direction of the display panel surface.

The lens unit changes the direction of light emitted in the normal direction of the display panel surface to deviate from the normal line, and changes a part of the light emitted in a direction deviating from the normal line of the display panel surface to the normal direction. That is, by changing the direction of the light emitted by the lens unit according to the audio visual angle, it is possible to induce color mixing to improve the color shift.

The lens section 23 includes a polygonal cross-section stripe pattern, a polygonal cross-section wave pattern, a polygonal cross-section matrix pattern, a polygonal cross-section honeycomb pattern, a polygonal cross-sectional dot pattern, a polygonal cross-section concentric circle pattern, a semi-circular cross-section stripe pattern, a semi-circular cross-section wave pattern, a semi-circular cross-section matrix pattern , Semi-circular cross-section honeycomb pattern, semi-circular cross-sectional dot pattern, semi-circular cross-section concentric pattern, semi-ellipse cross-section stripe pattern, semi-ellipse cross-section wave pattern, semi-ellipse cross-section matrix pattern, semi-ellipse cross-section honeycomb pattern, semi-ellipse cross-dot dot pattern The pattern, the half-oval cross-sectional stripe pattern, the half-oval cross-sectional wave pattern, the half-oval cross-section matrix pattern, the half-oval cross-section honeycomb pattern, the half-oval cross-sectional dot pattern, the half-oval cross-section concentric circle pattern.

Here, the polygonal cross section may be a triangular cross section, a trapezoidal cross section, a square cross section, or the like. In addition, the half-oval cross section can draw other curve trajectories other than circular arcs and elliptical arcs. In addition, the semicircle, the semi-ellipse, and the half-oval mean not only the shape of dividing the circle, the ellipse, and the oval by exactly 1/2, but also a part of the cross section of the lens portion including an arc, an ellipse, and a parabola. do. That is, a figure in which both sides are an elliptical arc and a bottom is a straight line will be included in the semi-elliptic shape.

The color shift reducing layer of the comparative example is not limited thereto, and may have various forms, and the cross section is preferably symmetrical in cross section.

Also, for example, the stripe pattern may have various patterns such as a horizontal stripe pattern, a vertical stripe pattern, and the like. When it is formed in the horizontal direction, it is effective for vertical and vertical audiovisual compensation, and when it is formed in the vertical direction as shown in FIG. 6, it is effective for left and right audiovisual compensation.

In order to prevent the moiré phenomenon, the lens unit 23 may be formed to have a predetermined bias angle with respect to the side of the coating film layer 21. For example, in the case of a stripe pattern, the stripe may have a predetermined inclination angle with respect to the horizontal or vertical direction.

The lens unit 23 is preferably arranged in parallel with the lens unit spaced at regular intervals on one surface of the coating film layer 21, as shown in FIG.

The lens unit may be formed on the rear surface of the coating film layer facing the display panel, or may be formed on the front surface of the coating film layer facing the viewer. In addition, the lens unit may be formed on both sides of the coating film layer.

A plurality of lens units are formed to be spaced apart from each other. Here, a plurality of meanings means that a plurality of lens parts for refracting light based on the cross section of the coating film layer is formed to be spaced apart from each other, and a flat surface of the coating film layer for transmitting light exists between the lens parts. Thus, for example, the lens portion of the semi-elliptical cross-section matrix pattern can be viewed as a single lens portion of the matrix pattern when viewed from the front surface of the coating coating layer, but a plurality of semi-elliptic cross-section lens portions are formed to be spaced apart from each other based on the cross section of the coating coating layer. Will be.

8 is a view illustrating a method of manufacturing a color shift reducing layer of a comparative example.

The coating film layer 21 may be formed on the support 25.

As for the support body 25, the transparent resin film or glass substrate which has ultraviolet permeability is preferable. As the material of the support, for example, polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl chloride (PVC), triaccetic cellulose (TAC), or the like may be used. The refractive index of the support may be preferably the same as the refractive index of the coating film layer, but the present invention is not limited thereto.

In the method of forming the lens portion 23, after applying the ultraviolet curable resin on one surface of the support 25, the negative groove is formed in the ultraviolet curable resin using a forming roll formed on the surface of the mirror portion of the lens while irradiating ultraviolet rays. do. Thereafter, the ultraviolet curable resin is again irradiated with ultraviolet rays to complete the coating film layer 21 on which the lens portion 23 is finally formed.

However, the color shift reduction layer of the comparative example is not limited thereto, and the intaglio groove of the coating layer may be formed by various methods such as a heat press method using a thermoplastic resin, an injection molding method by filling a thermoplastic resin or a thermosetting resin, and molding. You can get it.

9 is a view showing a relationship between the depth D / width W ratio of the lens unit and the color shift improvement rate.

=0.004 이상이다. 따라서, 시청각 0도에서 60도 사이에서 최대

=0.02 수준의 컬러시프트를 갖는 디스플레이 패널(컬러시프트 특성이 가장 우수한 S-IPS 패널 기준)이 눈으로 구별되는 컬러시프트 개선 효과를 보이기 위해서는 적어도 색변화(color shift) 개선율이 20% 이상(최대

=0.016 이하)이어야 한다. 도 9의 그래프에서 색변화 개선율이 20% 이상이 되려면 렌즈부 깊이/폭의 비가 0.25 이상이어야 함을 알 수 있다. 또한, 렌즈부의 깊이/렌즈부의 폭의 비가 6을 초과하면, 통상적인 렌즈부 형성 방법으로는 필름의 제조가 불가능하므로, 렌즈부의 깊이/렌즈부의 폭은 6 이하가 되어야 한다. The color shift distinguished by eyes

= 0.004 or more. Thus, the maximum of between 0 and 60 degrees of audio visual angle

Display panel with color shift of = 0.02 level (based on S-IPS panel that has the best color shift characteristics) has a color shift improvement of at least 20% (max.

= 0.016 or less). In the graph of FIG. 9, it may be seen that the ratio of the depth / width of the lens part should be 0.25 or more in order for the color change improvement rate to be 20% or more. In addition, when the ratio of the depth of the lens portion to the width of the lens portion exceeds 6, since the film cannot be manufactured by the conventional lens portion forming method, the depth of the lens portion / width of the lens portion should be 6 or less.

FIG. 10 is a diagram showing the relationship between the ratio of the interval c / pitch P of the lens portion to the color shift improvement rate.

Similarly, for the color shift improvement rate to be 20% or more in the graph of FIG. 10, the ratio of the pitch between the lens portions / the pitch of the lens portions should be 0.95 or less.

11 is a view showing the relationship between the ratio of the interval C / pitch P and the transmittance of the lens portion.

As shown in the graph of FIG. 11, the film transmittance increases as the ratio between the lens sections / lens pitches increases. If the film transmittance is more than 50%, it is valuable as a commodity, and if the transmittance is more than 50%, the ratio between the lens unit pitch / lens unit pitch must be 0.5 or more.

Thus, it can be seen from the graphs of FIGS. 10 and 11 that the preferred inter-lens spacing / lens pitch should be 0.5-0.95.

12 to 17 are views showing the relationship between the shape of the cross section of the lens unit and the dual phase.

As shown in Fig. 12, the lens portion having the semi-elliptical cross section was most effectively incurred when the ghost was observed while varying the curvature of the lens portion (27 μm in width, 81 μm in depth, 90 μm in pitch). It can be suppressed.

From the semi-ellipse to the triangle, that is, the curvature decreases, the ghost is clearly observed. 13 to 17 are diagrams showing the luminance distribution of the original image and the luminance distribution of the virtual image.

18 to 20 are views illustrating that double phases and haze are generated when the color shift reducing layer is spaced apart from the display panel.

When the color shift reduction layer of the comparative example is mounted in front of the display panel, as shown in FIG. 18, the color shift reduction layer is spaced apart from the display panel, and as the distance thereof increases, the dual phase becomes more pronounced. 19 is a view showing that a dual phase is generated when the color shift reducing layer is spaced apart from the display panel. This double image distorts the image of the display panel. Accordingly, there is a need for a method of reducing the color shift and not generating a double phase.

In addition, when the color shift reducing layer is spaced apart from the display panel, as well as the above-described dual phase problem, as shown in FIG. 20, the lens unit is configured to cover the flat surface between the lens portions and external light reflected from the display panel. It also has a problem of causing diffusion and haze. That is, external light incident on the color shift reduction layer and the display panel is reflected or multi-reflected at the interface between the color shift reduction layer and air (air between the color shift reduction layer and the display panel) and at the interface between the air and the display panel. It is then incident on the lens portion and then diffuses to generate haze. This phenomenon lowers the contrast ratio and lowers the visibility of the panel. Accordingly, there is a need for a solution capable of improving double phase generation and haze generation of the color shift reduction layer.

21 to 23 are views illustrating methods of removing a double phase and haze of a color shift reducing layer, and FIG. 21 is a view schematically showing a display device of a comparative example, and FIG. 22 is a view showing that a double phase is removed from the display device of FIG. 21. 23 is a diagram schematically illustrating a display device according to another comparative embodiment.

By bringing the color shift reduction layer into close contact with the display panel, the double phase and the haze can be removed. For example, as shown in FIG. 21, the color shift reducing layer is adhered to the display panel using the adhesive 31, or as shown in FIG. 23, a coating film layer is formed of a material having self-adhesiveness and the coating film layer is directly attached to the display panel. By adhering, double phase and haze generation can be suppressed and a transmittance | permeability can be improved. In addition, the color shift reducing layer is simply adhered to the display panel without sticking, so that the air layer is not interposed therebetween. When the color shift reducing layer is in close contact with the display panel, it is difficult to distinguish between the dual phase and the original phase because the gap is very small.

At this time, it is preferable that the lens portion is directed toward the display panel side rather than the viewer side in terms of haze reduction. (This is also the case when the color shift reducing layer is provided apart from the display panel.)

Here, the coating layer having a self-adhesive is made of a transparent elastomer that can be cured by ultraviolet light and can be directly attached to the display panel. Materials include acrylic elastomers, silicone elastomers (PDMS), urethane elastomers, polyvinyl butyral (PMB) elastomers, ethylene-vinyl acetate (EVA) elastomers, polyvinyl Ether-based elastomers, saturated amorphous polyester-based elastomers, melamine resin-based elastomers, and the like can be used.

Table 1 below shows the results of measuring the haze caused by external light in the display device in which the color shift reducing layer is spaced apart from the display panel, and the display device of FIG. 21.

Sample Luminance value measured at 60 degree of audio visual angle Black panel 1.73 nit Color shift reduction layer of display panel / air / half-oval cross-section lens part 12.27 nit Color shift reduction layer of display panel / PSA / semi-elliptical lens 2.58 nit Display panel / air / PET film 3.87 nit

In the measurement method, a sample was attached to a black substrate under conditions of 240 lux of external light and the luminance of reflected light was measured at 60 degrees of left and right audiovisual angles. Since external light exists above the sample, the portion corresponding to the specular reflection can be observed from the bottom of the sample, and the diffuse reflection can be observed from all directions. Therefore, the reflection haze by external light was measured by measuring diffusely reflected light at 60 degrees on the side rather than the bottom of the sample.

When the color shift reduction layer is adhered to (or directly attached to) the display panel, the measured reflection haze is 2.58 nit, which is very small compared to the presence of an air layer spaced apart, even when compared to a PET film without a lens portion. It can be seen that the reflection haze is significantly reduced.

24 to 27 are views showing color shift improvement, gray level inversion, and gamma curve distortion improvement by a color shift reduction layer of a comparative example in an LCD monitor (model name: B2440MH) employing a CCFL BLU and a TN panel.

In order to measure the degree of color shift improvement, an SS320 goniometer was used as a measuring device. Color coordinates were measured at intervals of 10 degrees up to 0 to 60 degrees up and down of the display panel, and the color shift was converted into color shifts to obtain FIG. 24. The color shift reduction layer samples were directly attached to the panel and measured in the same manner to obtain FIG. 25. As a result, the color shift improvement rate was found to be 25.5% (top) and 65.4% (bottom).

In order to measure the degree of gray level reversal and gamma curve distortion improvement, CS-1000 was used as a measuring device. 26 was obtained by measuring the luminance of each gray level of W, R, G, and B at an angle of 30 degrees and 50 degrees up and down on the front of the display panel. To obtain FIG. 27. As a result, the linearity of the gamma curve is restored when the color shift reduction layer is applied, thereby improving the gray scale inversion, the variation between the gamma curves for each angle is significantly reduced, and the distortion of the gamma curve is reduced.

28 to 31 are views showing improvement in color shift, gray level inversion, and gamma curve distortion by the color shift reduction layer of the comparative example in an LCD monitor (model name: BX2440) employing an LED BLU and a TN panel.

In order to measure the degree of color shift improvement, an SS320 goniometer was used as a measuring device. Color coordinates were measured at intervals of 10 degrees up to 0 to 60 degrees up and down of the display panel to obtain color shift, and FIG. 28 was obtained. The color shift reduction layer sample was directly attached to the panel and measured in the same manner to obtain FIG. 29. As a result, it was found that the color shift improvement rates were 30.9% (top) and 63.5% (bottom).

In order to measure the degree of gray level reversal and gamma curve distortion improvement, CS-1000 was used as a measuring device. FIG. 30 was obtained by measuring the luminance for each gray level of W, R, G, and B at an angle of 30 degrees and 50 degrees up and down of the display panel, and the color shift reduction layer sample was directly attached to the panel and measured in the same manner to obtain FIG. As a result, the linearity of the gamma curve is restored when the color shift reduction layer is applied, thereby improving the gray scale inversion, the variation between the gamma curves for each angle is significantly reduced, and the distortion of the gamma curve is reduced.

32 to 35 are views illustrating improvement of color shift and gamma curve distortion by the color shift reduction layer of the comparative example in a 46-inch LCD TV (model name: LH46CSPLBC) employing an S-PVA panel.

  In order to measure the degree of color shift improvement, an SS320 goniometer was used as a measuring device. The color coordinates were measured at intervals of 10 degrees to the left and right 0 to 60 degrees of the display panel and converted into color shifts to obtain FIG. 32. The color shift reduction layer samples were directly attached to the panels and measured in the same manner to obtain FIG. 33. As a result, the color shift improvement rate was found to be 48.7% (left) and 53.7% (right).

In order to measure the improvement of gamma curve distortion, CS-1000 was used as a measuring device. FIG. 34 was obtained by measuring luminance of each gray level of W, R, G, and B at an angle of 30 degrees and 50 degrees at the front and left of the display panel. Got it. As a result, it can be seen that the change between the gamma curves for each angle is significantly reduced when the color shift reduction layer is applied.

36 is a view illustrating color change of an S-IPS mode LCD TV without a color shift reducing layer of a comparative example, and FIG. 37 is a color shift reducing layer (lens) of a comparative example having self-adhesiveness to the LCD TV of FIG. 36. Negative width 30 占 퐉, depth 60 占 퐉, pitch 83 占 퐉, semi-elliptic cross section) were attached to the display panel, and the results of the color change improvement were measured. The color change improvement rate was 50%.

38 to 40 are diagrams showing the relationship between the size of the lens portion and the dual image generation, and FIG. 41 is a diagram showing the relationship between the size of the lens portion and moiré generation.

The color shift reduction optical film is provided in close contact with the display panel, and the pitch of the lens portion is set to 45 µm or less, thereby preventing the occurrence of double images of the color shift reduction optical film. Preferably, the pitch is preferably 45 µm or less while satisfying the above-described ratio of the depth / width of the lens portion to the interval / pitch between the lens portions. On the other hand, when there is a lens portion having a size of 0.01 μm or less, the film acts as a thin film that is halfway between the refractive index of the film and the refractive index of air, rather than the color mixing caused by the light reflection, refraction, or scattering effects. Therefore, it is preferable that the pitch of a lens part is 0.01 micrometer or more.

Table 2 below shows the size of the lens unit of each sample. In this case, the ratio of the depth / width of the lens portion and the ratio of the interval / pitch between the lens portions is the same.

Sample Width (μm) Depth (μm) Pitch (μm) # 6_ref. 20 62.5 90 # 6_P1 10 31.25 45 # 6_P2 6 18.75 27 # 6_P3 4 12.5 18

38 to 40 show a result of measuring luminance in a circular image along a line passing through the center. At the two intersections where the line passing through the center meets the image as shown, two peaks appear in Sample # 6_ref., Whereas Sample # 6_P1 in FIG. 38, Sample # 6_P2 in FIG. 39, and Sample # 6_P3 in FIG. It can be seen that the occurrence of double phase is reduced.

As shown in FIG. 41, while moiré is generated in sample # 6_ref., It is understood that moiré is not generated in sample # 6_P1.

<Invention>

By disposing the color shift reducing layer of the above-described comparative example in front of the display panel, color shift could be greatly improved. In addition, gamma curve distortion and gray level inversion could be improved. Furthermore, by placing the color shift reduction layer in close contact with the front of the display panel, the problem of double phase and haze was solved.

The principle and configuration of the color shift and gradation inversion improvement and the biphasic and haze reduction of the comparative example are also essential in the present invention. In addition, in the present invention, the color shift reducing layer is arranged closer to the liquid crystal layer, thereby further improving the problems of i) lowering sharpness of image quality and lowering contrast ratio due to increased haze, and ii) increasing dual phase. present.

42 and 43 are views schematically showing color shift reducing liquid crystal display panels according to embodiments of the present invention.

The liquid crystal display panel of the present invention includes a liquid crystal layer 11 between the front polarizing layer 15 and the rear polarizing layer 19. The color shift reducing layer 20 is provided between the liquid crystal layer 11 and the front polarizing layer 15. The color shift reduction layer 20 reduces color shift by mixing light emitted from the liquid crystal layer 11 with different colors depending on the viewing angle and gray level due to the birefringence characteristic of the liquid crystal layer 11.

The color shift reduction layer 20 includes a plurality of intaglio lens portions 23 that are formed to be spaced apart from each other on the layered coating film layer 21 and the coating film layer 21. The emission direction of the light incident on the lens unit 23 is dispersed and mixed with the light passing between the lens units 23 spaced apart from each other, thereby reducing color shift.

The color shift reducing layer 20 may be the front transparent substrate 13, as shown in FIG.

In addition, as shown in FIG. 43, a layer separate from the front transparent substrate 13 may be provided between the front transparent substrate 13 and the front polarizing layer 15. In this case, the color shift reduction layer 20 may be adhered to the front transparent substrate 13 by an adhesive, or may be directly attached to the front transparent substrate 13 having self adhesiveness.

The color shift reduction layer 20 may include a support. For example, a color shift reduction layer 20 may be formed by applying a resin such as acrylic, silicone, or the like onto an isotropic support such as a PC film, a TAC film, or the like, and then patterning the resin. Here, the support must use an isotropic film. Otherwise, the light phase is changed by the anisotropic support in the display panel, causing light leakage.

(External light intensity: 500 Lux) rescue Frontal black luminance Black luminance at 50 degrees audio visual Color shift reduction layer / front polarization layer with front transparent substrate / lens section 1.2 nit 3.4 nit Color shift reduction layer with front transparent substrate / front polarizing layer / lens 3.7 nit 12.27 nit

Table 3 shows the results of experiments with black luminance in the liquid crystal display of FIG. As can be seen from Table 3, when the color shift reducing layer 20 is located between the front transparent substrate 13 and the front polarizing layer 15, it exhibits a low black luminance value, and therefore, the clear contrast ratio is further increased. It can be seen that excellent.

The color shift reduction layer 20 of the present invention improves the color change and gray level reversal appearing in terms of front contrast without deteriorating image quality (dual image generation, MTF (Modulation Transfer Function) reduction, etc.) and lowering the contrast ratio, and furthermore, viewing angle. It can provide an improved image.

Unexplained reference numeral 19 denotes a rear transparent substrate.

Claims (8)

As a liquid crystal display device,
A liquid crystal layer is provided between the front polarizing layer and the rear polarizing layer,
A color shift reducing layer is provided between the liquid crystal layer and the front polarizing layer,
The color shift reducing layer may include a coating layer that forms a layer and a plurality of intaglio lenses formed on the coating layer to be spaced apart from each other, and directly adheres to the front transparent substrate of the liquid crystal display device with self adhesiveness.
Due to the birefringence characteristic of the liquid crystal layer, among the light emitted from the liquid crystal layer in different colors according to the viewing angle and the gray level, the emission direction of the light incident on the lens unit is dispersed, and passes between the lens units spaced apart from each other. Color shift reduction liquid crystal display device characterized by mixing with light. delete The method of claim 1,
The color shift reducing layer is a color shift reducing liquid crystal display device, characterized in that provided between the front transparent substrate and the front polarizing layer of the liquid crystal display device. delete The method of claim 1,
The cross-section of the lens portion comprises an elliptical arc, color shift reduced liquid crystal display device. The method of claim 1,
And the lens portion has a ratio of the depth of the lens portion to the width of the lens portion of 0.25 or more. The method of claim 1,
And the lens unit has a ratio between a lens unit pitch / lens pitch of 0.5 to 0.95. The method of claim 1,
And the lens portion has a pitch of 45 µm or less.

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