KR20070024781A - LCD with improved wide viewing angle - Google Patents

Abstract

The present invention provides a liquid crystal display device comprising: two upper and lower glass substrates; A polarizing plate having two absorption axes orthogonal to each other, positioned between the two glass substrates; A vertical alignment panel having a negative or positive dielectric anisotropy and positioned between the two polarizing plates; And a phase difference film that satisfies the conditions of Equations 1, 2, and 3, and is positioned between the two polarizing plates, and has two axes in which the optical axis is perpendicular to the absorption axis of the adjacent polarizing plate. As the wavelength increases, the in-plane retardation value R _in increases with the reverse wavelength dispersion characteristic, and the absolute value of the retardation value R _{th in the} thickness direction decreases with the negative value of the normal wavelength dispersion characteristic. The sum total is 30 to 150 nm in proportion to the wavelength in the visible light range, and the liquid crystal molecules of the vertical alignment panel are free of 75 to 90 degrees with no voltage applied between the two glass substrates. Retardation film having a tilt angle; It provides a liquid crystal display device comprising a, wherein the liquid crystal display device according to the present invention has the effect of improving the contrast characteristics at the inclination angle, and minimize the color change according to the viewing angle in the black state (black state) (Equations 1 to 3 are the same as the contents described in the specification body).

Description

Liquid crystal display with improved wide viewing angle characteristics {Liquid-crystal display}

1 is a perspective view of a VA-LCD cell including a retardation film according to Example 1 of the present invention.

2 is a perspective view of a VA-LCD cell including a retardation film according to a second embodiment of the present invention.

3 is a perspective view of a VA-LCD cell including a retardation film according to a third embodiment of the present invention.

Figure 4 is a graph showing the wavelength dispersion characteristics dependence of the wavelength direction retardation value and the surface retardation value of the retardation film applied in the present invention.

5 is a transmittance (a) according to a viewing angle of a black state of a VA-LCD to which a retardation film according to the present invention is applied, and a transmittance (b) to a viewing angle of a dark state of a VA-LCD to which a general biaxial retardation film is applied (b) ) Is the result of simulation.

6 is a color change of the black state for the VA-LCD to which the retardation film according to the present invention is applied when white light is used while changing the inclination angle in the range of 0 ° to 70 ° at 2 ° intervals at 45 ° longitude. It is the result of simulating the color change (b) of the dark state of VA-LCD to which (a) and the general biaxial retardation film were applied.

7 is a simulation of the transmittance (a) of the dark state according to the wavelength of the VA-LCD to which the retardation film according to the present invention is applied and the transmittance (b) of the dark state according to the wavelength of the VA-LCD to which a general biaxial retardation film is applied. The result is.

FIG. 8 shows the results of simulating the contrast ratio for the VA-LCD structure of Example 1 when white light was used for tilt angles in the range of 0 ° to 80 ° at all east angles.

FIG. 9 shows the results of simulating the contrast ratio for the VA-LCD structure of Example 2 when white light was used for all tilt angles in the range of 0 ° to 80 °.

Fig. 10 simulates the color change of the black state for the VA-LCD structure of Example 2 when white light was used while changing the tilt angle in the range of 0 ° to 80 ° at 2 ° intervals at 45 ° east angle. One result.

FIG. 11 shows the results of simulating the contrast ratio for the VA-LCD structure of Example 3 when white light was used for tilt angles in the range of 0 ° to 80 ° at all east angles.

Fig. 12 shows the color change for the black state for the VA-LCD structure of Example 3 when white light was used, changing the inclination angle in the range of 0 ° to 80 ° at 2 ° intervals at 45 ° east angle. Is the result of the simulation.

* Description of the symbols in the drawings *

100: polarizer

110: 100 polarizing plate perpendicular to the absorption axis

200: vertical alignment panel

300: retardation film having two axes

310: phase difference film having two axes whose absorption axis is perpendicular to 300

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having improved wide viewing angle characteristics in a liquid-crystal display (hereinafter referred to as LCD).

The present invention relates to the dark state of a liquid crystal display (LCD), specifically a vertically aligned liquid-crystal display (VA-LCD) filled with liquid crystals having negative or positive dielectric anisotropy. A vertically oriented liquid crystal display device (hereinafter referred to as "VA-LCD") having a retardation film layer having two axes in order to minimize the color change and improve the wide viewing angle characteristics at the front and inclination angles.

One of the biggest weaknesses of liquid crystal displays (LCDs), which are widely used in the field of flat panel displays, is that the viewing angle is narrow. The reason why the image looks different depending on the viewing angle of the liquid crystal display device is the problem due to the anisotropy of the liquid crystal. And second, the imperfection of the polarizer.

In order to improve the wide viewing angle, which is one of the weak points of the liquid crystal display, a completely dark state and uniform brightness are required. In particular, unlike the TN mode, the VA- which has the initial orientation of the liquid crystal in the vertical direction is used. In the case of the LCD, there are two major problems of deteriorating the viewing angle characteristic, the first of which is the viewing angle dependency of the orthogonal polarizer, and the second is the viewing angle dependency of the birefringence characteristic of the VA-LCD panel.

According to these requirements and problems, various attempts have been made to improve the wide viewing angle of the liquid crystal display. As a specific improvement method, a narrow viewing angle due to the change of Δnd (the product of birefringence and the specimen spacing) according to the angle is obtained. A method of using a viewing angle compensation film to compensate and a multi-domain (MULTIDOMAIN) method of dividing a pixel into multiple domains to improve the viewing angle are used.

As a specific example of improving the wide viewing angle of the VA-LCD using the viewing angle compensation film, a -C-Plate compensation film (in the plane direction) is used to compensate for the dark state of the VA-LCD without voltage applied. A VA-LCD using n _x = n _y > n _z ) is disclosed in US Pat. No. 4,889,412 when the _x- axis refractive index is n _x , the y-axis refractive index is n _y , and the Z-axis refractive index is n _z . , VA-LCD containing only -C-Plate compensation film has the disadvantage that light leakage occurs at the inclination angle because it is not completely compensated.

In addition, an example of a compensation film including a -C-Plate compensation film and an A-Plate compensation film is shown in US Pat. No. 6,141,075. In this case, however, the minimum contrast at 70 degrees of inclination in the dark state is only 20: 1, so the contrast in front and inclination angles is improved to improve the viewing angle. It was a condition that the change of the color in the state of improvement is needed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that can obtain high contrast characteristics at the front and inclination angles of a VA-LCD and to improve the viewing angle characteristics of a VA-LCD by minimizing the color change of the dark state at the inclination angle. .

In order to achieve the above object, the present invention provides a liquid crystal display device comprising: two upper and lower glass substrates; A polarizing plate having two absorption axes orthogonal to each other, positioned between the two glass substrates; A vertical alignment panel having a negative or positive dielectric anisotropy and positioned between the two polarizing plates; And a phase difference film that satisfies the conditions of the following Equations 1, 2 and 3, is located between the two polarizing plates, and has two axes in which the optical axis is perpendicular to the absorption axis of the adjacent polarizing plate. As the wavelength increases within the range, the in-plane retardation value R _in increases with the reverse wavelength dispersion characteristic, and the absolute value of the retardation value R _{th in the} thickness direction decreases with the negative value of the normal wavelength dispersion characteristic. The sum is 30 to 150 nm in proportion to the wavelength within the visible light range, and the liquid crystal molecules of the vertical alignment panel are 75 to 90 degrees with no voltage applied between the two glass substrates. Retardation film having a pretilt angle; It provides a liquid crystal display device comprising a.

n _x > n _y > n _z

(Wherein n _x is the refractive index in the x-axis direction on the plane of the film, n _y is the refractive index in the y-axis direction on the plane of the film, and n _z is the refractive index in the thickness direction of the film)

R _in = d × (n _x -n _y )

(The R _in is the phase difference value on the surface of the film, the n _x is the refractive index of the x-axis direction on the surface of the film, the n _y is the refractive index of the y-axis direction on the surface of the film, d is the film Is the thickness of)

R _th = (n _z -n _y ) × d

(Where R _th is a retardation value in the thickness direction of the film, n _z is a refractive index in the thickness direction of the film, n _y is a refractive index in the y axis direction on the plane of the film, and d is a thickness of the film)

The pretilt angle may be 87 to 90 degrees, more preferably 89 to 90 degrees.

The retardation value of the liquid crystal layer of the vertical alignment panel may be 80 nm to 400 nm, more preferably 80 nm to 300 nm at a wavelength of 550 nm.

When voltage is applied, the director of the liquid crystal molecules of the vertical alignment panel may form 45 degrees with the absorption axis of the polarizer.

The in-plane retardation values R _{in, 400} , R _{in, 550} , and R _{in, 700} at wavelengths of 400 nm, 550 nm, _{and 700} nm, respectively, have wavelength dispersion characteristics R _{in, 400} / R _in at two wavelengths of 400 nm, 550 nm. _{, 550} may have a value in the range of 0.4 to 0.9, and the wavelength dispersion characteristics R _{in, 700} / R _{in, 550} at two wavelengths of 550 nm and 700 nm may have values in the range of 1.1 to 1.8.

The thickness direction retardation values R _{th, 400} , Rth, 550 and R _{th, 700} at the wavelengths of 400 nm, 550 nm and ₇₀₀ nm are respectively the wavelength dispersion characteristics R _{th, 400} / R _th at the two wavelengths 400 nm and 550 nm. _{, 550} may have a value in the range of 1.05 to 1.4, and the wavelength dispersion characteristics R _{th, 700} / R _{th, 550} at two wavelengths of 550 nm and 700 nm may have values in the range of 0.5 to 0.95.

The retardation value R _th in the thickness direction at a wavelength of 550 nm may have a value in the range of −50 nm to −500 nm.

The retardation film is a polymer produced by a method of co-polymerization or mixing a first monomer having a unique positive birefringence value and a second monomer having a unique negative birefringence value It can be produced by stretching.

The retardation film may be produced by laminating at least two or more retardation films having different dependences on the retardation value R _in and the thickness direction retardation value R _th according to the wavelength.

The objects, features and advantages of the present invention will be more readily understood by reference to the accompanying drawings and the following detailed description.

Hereinafter, the configuration and operation of the present invention with reference to the accompanying drawings in detail as follows.

1 to 3 illustrate a VA-LCD that can be implemented by the present invention, two polarizing plates 100 and 110 having absorption axes perpendicular to each other, a vertical alignment panel 200 disposed between the two polarizing plates, and the two The phase difference films 300 and 310 disposed between the polarizing plate and the vertical alignment panel constitute a VA-LCD cell. Here, the polarizing plates 100 and 110 may include a protective film having a triacate cellulose (TAC) protective film having a retardation value in a unique thickness direction or a retardation value in a thickness direction.

1 and 2 illustrate a cell having a thickness of 3 to 8 μm between a vertical alignment panel 200 and two upper and lower polarizers 110 and 100 orthogonal to each other using one phase difference film 300 or 310 having two axes. A structure of a VA-LCD cell according to Example 1 configured to hold a gap.

FIG. 1 illustrates an embodiment in which the retardation film 300 is disposed between the vertical alignment panel 200 and the lower polarizing plate 100, wherein the optical axis of the retardation film 300 is the lower polarizing plate. It is arrange | positioned perpendicular to the absorption axis of (100).

FIG. 2 illustrates a second embodiment in which the retardation film 310 is disposed between the vertical alignment panel 200 and the upper polarizing plate 110, wherein the optical axis of the retardation film 300 is the upper polarizing plate. It is arrange | positioned perpendicular to the absorption axis of 110.

3 is disposed between the vertical alignment panel 200 and the two upper and lower polarizers 110 and 100 orthogonal to each other using two phase difference films 310 and 300 to maintain a cell gap of 3 to 8 μm. As a structure of a VA-LCD cell according to the third embodiment configured to be, Figure 3 is disposed one retardation film 300 between the vertical alignment panel 200 and the lower polarizing plate 100 and the other retardation film 310 Is disposed between the vertical alignment panel 200 and the upper polarizing plate 110, wherein the retardation film 300 disposed between the vertical alignment panel 200 and the lower polarizing plate 100 has a lower optical axis The retardation film 310 disposed perpendicular to the absorption axis of the polarizing plate 100 and disposed between the vertical alignment panel 200 and the upper polarizing plate 110 has an optical axis perpendicular to the absorption axis of the upper polarizing plate 110. It is arranged.

The retardation films 300 and 310 according to the present invention have a refractive index of n _x > n _y > n _z . Here, n _x represents a refractive index in the x-axis direction parallel to the surface of the film, n _y represents a refractive index in the y-axis direction parallel to the surface of the film, and n _z represents a refractive index in the thickness direction perpendicular to the surface of the film.

The retardation film has the following main characteristics.

In-plane retardation value of the retardation film (R _in = d × (n _x -n _y ), where d is the thickness of the film) is the reverse wavelength dispersion in which the retardation value increases as the wavelength increases in the visible light range (reversed wavelength dispersion) characteristics.

The retardation value in the thickness direction of the retardation film (R _th = d × (n _z -n _y ), where d is the thickness of the film) is a negative value, and the absolute value of the retardation value in the thickness direction increases as the wavelength increases in the visible light range. It should have a characteristic of normal wavelength dispersion with decreasing value.

Figure 4 is a reference diagram showing the dependence of the retardation value according to the wavelength of the retardation film according to the present invention, the wavelength dispersion characteristics (R _{th, λ} / R _{th, 550} ) of the thickness direction retardation value of the retardation film, and planar The wavelength dispersion characteristic (R _{in, λ} / R _{in, 550} ) of the phase difference value is shown.

As shown in FIG. 4, in the retardation film according to the present invention, an appropriate wavelength dispersion characteristic of the planar retardation value is a relative retardation ratio value (R _{in, 400} / R _{in, 550} ) at two wavelengths of 400 nm and 550 nm. It should have a value in the range of 0.4 to 0.9, and the relative phase difference ratio value (R _{in, 700} / R _{in, 550} ) at 550 nm and 700 nm should have a value _{in the} range of 1.1 to 1.8. Here, R _{in, 400} is a planar phase difference value at ₄₀₀ nm wavelength, R _{in, 550} is a planar phase difference value at ₅₅₀ nm wavelength, and R _{in, 700} is a planar phase difference value at ₇₀₀ nm wavelength.

The retardation film has its plane retardation R _{in, 550} = d × according to the present invention the appropriate range of (n _x n _y) is in 30㎚~150㎚ 550㎚ wavelength.

In addition, the proper wavelength dispersion characteristic of the thickness direction retardation value of the retardation film according to the present invention, the relative retardation ratio value (R _{th, 400} / R _{th, 550} ) at the two wavelengths 400nm, 550nm range of 1.05 to 1.4 The relative retardation ratio value (R _{th, 700} / R _{th, 550} ) at the two wavelengths of 550 nm and 700 nm should have a value in the range of 0.5 to 0.95.

An appropriate range of the thickness direction retardation value R _{th, 550} = d x (n _z -n _y ) is -50 nm to -500 nm at a wavelength of 550 nm.

Therefore, when the liquid crystal display device shown in FIGS. 1 to 3 is manufactured using the retardation film according to the present invention, complete compensation of the dark state of the VA-LCD at the inclination angle is possible, and the dark state, It is possible to minimize the color change of the bright state and RGB color.

5 is a transmittance according to a viewing angle of a black state of a VA-LCD to which a retardation film according to the present invention is applied, and a transmittance according to a viewing angle of a dark state of a VA-LCD to which a conventional biaxial retardation compensation film is applied. As a result of comparing (b), when the retardation film according to the present invention is applied, it can be seen that the black state compensation characteristics are better.

For reference, the conventional biaxial retardation compensation film was used as a polycarbonate retardation film, and the wavelength dispersion characteristic, (R _{th, 400} / R _{th, 550} ) = (R _{in, 400} / R _{in, 550} ) = 1.15 was used.

6 is a color change of a black state for a VA-LCD to which a retardation film of the present invention is applied when white light is used while changing an inclination angle in a range of 0 ° to 70 ° from an east angle at 2 ° (a ) And the color change (b) of the dark state of the VA-LCD to which the existing biaxial retardation compensation film is applied, and show that the dark state color change is much smaller when the retardation film according to the present invention is used. Able to know.

When the retardation film according to the present invention is used in comparison with the conventional biaxial retardation compensation film, the reason of showing low transmittance in the dark state and a small color change in the dark state is that the change in transmittance according to the wavelength is flat. to be.

As a method for producing the retardation film according to the present invention, it is possible to produce by laminating two or three existing films having different wavelength dependence of retardation values.

In addition, the retardation film according to the present invention is produced by co-polymerizing the first monomer (monomer) having a unique positive birefringence value and the second monomer (monomer) having a unique negative birefringence value Of course, it can be produced by stretching the polymer or a polymer produced by mixing the first monomer (monomer) and the second monomer (monomer).

Examples of compensating VA-LCD using the retardation film according to the present invention are as follows, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

Example 1

A VA-LCD shown in Fig. 1, in which one retardation film having two axes is applied, includes a vertical alignment panel having a 3 mu m cell gap. A pretilt angle of 89 °, a dielectric constant anisotropy of Δε = -4.9, a refractive index anisotropy of Δn = 0.0979 and a wavelength dispersion characteristic of Δn ₄₀₀ / Δn ₅₅₀ = 1.096 were used. Therefore, the retardation value in the thickness direction of the vertical alignment panel is R _{VA, 550} = 297 nm. The retardation film was made of a polycarbonate-based material, the thickness retardation value is R _th (550 nm) = -270 nm, the planar retardation value is R _in (550 nm) = 67 nm. The wavelength dispersion characteristic of the thickness retardation value is R _th (450 nm) / R _th (550 nm) = 1.15, and the wavelength dispersion characteristic of the surface retardation value is R _in (450 nm) / R _in (550 nm) = 0.652. .

The results of simulating the contrast characteristics of the VA-LCD compensated using the retardation film are shown in FIG. 8, and the color change of the dark state of the VA-LCD compensated using the retardation film is shown in FIG. Indicated.

Example 2

The VA-LCD shown in FIG. 2 using one retardation film having two axes includes a vertical alignment panel having a 3 μm cell gap. A pretilt angle of 89 °, a dielectric constant anisotropy of Δε = -4.9, a refractive index anisotropy of Δn = 0.0979 and a wavelength dispersion characteristic of Δn ₄₀₀ / Δn ₅₅₀ = 1.096 were used. Therefore, the retardation value in the thickness direction of the vertical alignment panel is R _{VA, 550} = 297 nm.

The retardation film was made of TAC (Triacetate cellulose) material, the thickness retardation value R _th (550 nm) = -241 nm, the planar retardation value is R _in (550 nm) = 44 nm.

The wavelength dispersion characteristic of the thickness retardation value is R _th (450 nm) / R _th (550 nm) = 1.12, and the wavelength dispersion characteristic of the surface retardation value is R _in (450 nm) / R _in (550 nm) = 0.61. .

The results of simulating the contrast characteristics of the VA-LCD compensated using the retardation film are shown in FIG. 9, and the color change of the dark state of the VA-LCD compensated using the retardation film is shown in FIG. 10.

Example 3

The VA-LCD shown in FIG. 3 using two retardation films having two axes includes a vertical alignment panel having a 3 μm cell gap. A pretilt angle of 89 °, a dielectric constant anisotropy of Δε = -4.9, a refractive index anisotropy of Δn = 0.0979 and a wavelength dispersion characteristic of Δn ₄₀₀ / Δn ₅₅₀ = 1.096 were used. Therefore, the retardation value in the thickness direction of the vertical alignment panel is R _{VA, 550} = 297 nm. Each of the two retardation films was made of a polycarbonate-based material, and the thickness retardation value was R _th (550 nm) = − 119 nm and the planar retardation value was R _in (550 nm) = 44 nm.

The wavelength dispersion characteristic of the thickness retardation value is R _th (450 nm) / R _th (550 nm) = 1.24, and the wavelength dispersion characteristic of the surface retardation value is R _in (450 nm) / R _in (550 nm) = 0.585. .

The results of simulating the contrast characteristics of the VA-LCD compensated using the retardation film are shown in FIG. 11, and the color change of the dark state of the VA-LCD compensated using the retardation film is shown in FIG. 12.

8, 9, and 11, in the case of the liquid crystal display according to the present invention, it was confirmed that the display panel had high contrast characteristics at all angles. According to FIGS. 10 and 12, the liquid crystal display according to the present invention. In the case of the device, it was confirmed that the color change of the dark state at the inclination angle is minimized.

According to the present invention, the VA-LCD having a biaxial retardation compensation film is capable of completely dark state compensation at the inclination angle of the VA-LCD, and in the dark state, the white state and the RGB state It is possible to improve the viewing angle characteristics by minimizing the color change.

Although the present invention has been described in detail with reference to the described embodiments, various modifications and changes are possible by those skilled in the art within the scope and spirit of the present invention, as well as such modifications and modifications belong to the appended claims. It is also natural.

Claims (11)

In the liquid crystal display device, Two upper and lower glass substrates; A polarizing plate having two absorption axes orthogonal to each other, positioned between the two glass substrates; A vertical alignment panel having a negative or positive dielectric anisotropy and positioned between the two polarizing plates; And The phase difference film which satisfies the conditions of the following equations (1), (2) and (3), is located between the two polarizing plates, and has two axes in which the optical axis is perpendicular to the absorption axis of the adjacent polarizing plate. As the wavelength increases, the in-plane retardation value R _in increases with the reverse wavelength dispersion characteristic, and the absolute value of the retardation value R _{th in the} thickness direction decreases with the negative value of the normal wavelength dispersion characteristic. The sum total is 30-150 nm in proportion to the wavelength within the visible light range, and the liquid crystal molecules of the vertical alignment panel are free of 75-90 degrees with no voltage applied between the two glass substrates. Retardation film having a tilt angle; Liquid crystal display comprising a. [Equation 1] n _x > n _y > n _z N _x is the refractive index in the x-axis direction on the plane of the film, N _y is a refractive index in the y-axis direction on the plane of the film, N _z is a refractive index in the thickness direction of the film [Equation 2] R _in = d × (n _x -n _y ) R _in is a phase difference value on the surface of the film, N _x is the refractive index in the x-axis direction on the plane of the film, N _y is a refractive index in the y-axis direction on the plane of the film, D is the thickness of the film [Equation 3] R _th = (n _z -n _y ) × d R _th is a retardation value in the thickness direction of the film, N _z is a refractive index in the thickness direction of the film, N _y is a refractive index in the y-axis direction on the plane of the film, D is the thickness of the film The method of claim 1, And the pretilt angle is 87 to 90 degrees. The method of claim 1 And the pretilt angle is 89 to 90 degrees. The method of claim 1, And a phase difference value of the liquid crystal layer of the vertical alignment panel has a range of 80 nm to 400 nm at a wavelength of 550 nm. The method of claim 4, wherein And a phase difference value of the liquid crystal layer of the vertical alignment panel is 80 nm to 300 nm at a wavelength of 550 nm. The method of claim 1, The liquid crystal display device, characterized in that the director of the liquid crystal molecules of the vertical alignment panel when the voltage is applied to the absorption axis of the polarizing plate 45 degrees. The method of claim 1, The retardation values R _{in, 400} , R _{in, 550} , and R _{in, 700 respectively} at 400 nm, 550 nm, _{and 700} nm wavelengths have wavelength dispersion characteristics R _{in, 400} / R _in at two wavelengths 400 nm, 550 nm. _{And 550} have values in the range of 0.4 to 0.9, and the wavelength dispersion characteristics R _{in, 700} / R _{in, 550} at two wavelengths of 550 nm and 700 nm have values in the range of 1.1 to 1.8. The method of claim 1, Each of the thickness retardation value in 400㎚, 550㎚, 700㎚ wavelength _{R th, 400, R th,} 550, R th, 700 a, 400㎚ two wavelengths, the wavelength dispersion property in 550㎚ R _{th, 400} / R _{th, 550} has a value in the range of 1.05 to 1.4, and wavelength dispersion characteristics R _{th, 700} / R _{th, 550} at two wavelengths of 550 nm and 700 nm have a value in the range of 0.5 to 0.95. . The method of claim 1, And the phase difference value (R _th ) in the thickness direction at a wavelength of 550 nm has a value ranging from -50 nm to -500 nm. The method of claim 1, The retardation film is a polymer produced by the method of co-polymerization or mixing a first monomer having a unique positive birefringence value and a second monomer having a unique negative birefringence value Liquid crystal display device characterized in that it is produced by stretching. The method of claim 1, The retardation film is a liquid crystal display device characterized in that at least two or more retardation film having a dependency of the retardation value (R _in ) and the thickness direction retardation value (R _th ) according to the wavelength is laminated.

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