TWI412844B - Reflective liquid crystal display - Google Patents

Abstract

A reflective liquid crystal display includes a polarizer, a first compensator, and a liquid crystal unit. The liquid crystal unit includes a first liquid crystal molecule whose longitudinal shaft is perpendicular to the polarizer. The first compensator is set between the polarizer and the liquid crystal unit, to compensate a linear polarized light beam transmitted out from the first liquid crystal molecule. Phase delay of the linear polarized light beam can be compensated by the first compensator; this reduces an occurrence of a leakage of the linear polarized light.

Description

Reflective liquid crystal display

The present invention relates to a reflective liquid crystal display, and more particularly to a reflective liquid crystal display capable of reducing light leakage.

At present, liquid crystal display technology is maturing, and the share of liquid crystal displays in the display market is also growing. Typical liquid crystal displays mainly include transmissive liquid crystal displays and reflective liquid crystal displays. The transmissive liquid crystal display mainly uses a backlight module to provide a light source required for display, and further selectively transmits a light beam emitted from the light source by a state transition of the liquid crystal layer upon power-on, thereby completing a display operation. The reflective liquid crystal display mainly uses a reflective film layer to reflect ambient light transmitted through the liquid crystal layer to complete a display operation.

As shown in FIG. 1, the conventional reflective liquid crystal display 1 mainly includes a polarizer 10, a liquid crystal cell 20, and a reflection unit 30. The liquid crystal cell 20 mainly includes conductive glass 21, 22, alignment films 23, 24, and liquid crystal molecules 25. The alignment film 23 is formed on the inner surface of the conductive glass 21, and the alignment film 24 is formed on the inner surface of the conductive glass 22. The liquid crystal molecules 25 are filled between the alignment films 23, 24. Among them, the alignment films 23 and 24 are for rotating the liquid crystal molecules 25 within the liquid crystal cell 20 by a certain angle.

The external ambient light beam passes through the polarizer 10 and is converted into a linearly polarized light beam. After the linearly polarized light beam passes through the conductive glass 21 and the alignment film 23, it is guided by the liquid crystal molecules 25 The liquid crystal cell 20 is reflected by the reflection unit 30, passes through the liquid crystal cell 20, and is finally transmitted by the polarizer 10. As shown in FIG. 2, when an electric field is applied to the electroconductive glass 21, 22, that is, when an electric field is applied to the liquid crystal cell 20, the liquid crystal molecules will be aligned in the direction of the electric field. Here, the linearly polarized light beam does not undergo any change when passing through the liquid crystal cell 20, and when reflected by the reflective unit 30, its polarization direction is rotated by 90 degrees. The linearly polarized beam that is reflected back will be absorbed by the polarizing plate 10. Therefore, the display function of characters and graphics can be realized by selecting a method of applying power to some areas of the liquid crystal cell 20 and not applying power to other areas.

However, since the liquid crystal molecules 25 are generally positive uniaxial molecules, birefringence occurs when the linearly polarized light beam is obliquely incident on the liquid crystal molecules, and thereby the linearly polarized light beam is converted into an elliptically polarized light beam. As shown in FIG. 3, the display angle of view of the liquid crystal cell 20 is limited based on the birefringence characteristics of the liquid crystal molecules 25 described above. When the linearly polarized light beam is transmitted through the liquid crystal cell 20 at an angle θ of both sides of the long axis of the liquid crystal molecules 25, it substantially satisfies the condition that can be absorbed by the polarizing plate 10. However, when the linearly polarized light beam is emitted from the outside of the angle θ on both sides of the long axis of the liquid crystal molecule 25, the polarization direction of the generated elliptically polarized light beam has exceeded a certain range. Therefore, the elliptically polarized light beam which is emitted outside the θ angle passes through the polarizing plate 10, thereby causing light leakage.

In view of this, it is necessary to provide a reflective liquid crystal display that can reduce light leakage.

A reflective liquid crystal display comprising a polarizer, a first compensation film and a liquid crystal cell. The liquid crystal cell includes a first liquid crystal molecule whose major axis is perpendicular to the polarizer. The first compensation film is located between the polarizer and the liquid crystal cell, To compensate for the phase delay caused by the first liquid crystal molecules to the linearly polarized beam.

The reflective liquid crystal display adopts a first compensation film to compensate a phase delay caused by the first liquid crystal molecules to the linearly polarized light beam, so as to adjust a polarization direction of the linearly polarized light beam, so that the linearly polarized light beam is transmitted through the liquid crystal unit and the first compensation film, and then is polarized. Absorption, reducing the generation of light leakage, thereby achieving the effect of increasing the viewing angle.

100‧‧‧Reflective LCD

110‧‧‧ polarizer

120‧‧‧First compensation film

130‧‧‧Second compensation film

140‧‧‧Liquid Crystal Unit

141‧‧‧First conductive glass

142‧‧‧Second conductive glass

143‧‧‧First alignment film

144‧‧‧Second alignment film

145‧‧‧First liquid crystal layer

146‧‧‧Second liquid crystal layer

149‧‧‧ liquid crystal molecules

150‧‧‧reflection unit

1 is a schematic structural view of a conventional reflective liquid crystal display.

2 is a schematic view showing the operation state of the reflective liquid crystal display of FIG. 1.

3 is a schematic view showing a viewing angle of a conventional reflective liquid crystal display.

4 is a schematic structural view of a liquid crystal display according to a preferred embodiment of the present invention.

FIG. 5 is a schematic view showing the display angle of the liquid crystal display of FIG. 4. FIG.

As shown in FIG. 4 , a reflective liquid crystal display 100 disclosed in a preferred embodiment includes a polarizer 110 , a first compensation film 120 , a second compensation film 130 , a liquid crystal cell 140 , and a reflective unit 150 . The first compensation film 120 and the second compensation film 130 are located between the polarizer 110 and the liquid crystal cell 140 to compensate the display viewing angle of the liquid crystal cell 140. The first compensation film 120 and the second compensation film 130 are all negative uniaxial compensation films, that is, the refractive index of the o light is greater than the refractive index of the e light. The liquid crystal molecules of the liquid crystal cell 140 are all positive uniaxial molecules, that is, the refractive index of the e light is greater than the refractive index of the o light.

The liquid crystal cell 140 includes a first conductive glass 141, a second conductive glass 142, a first alignment film 143, a second alignment film 144, a first liquid crystal layer 145, and a second liquid crystal layer 146. Wherein, the first conductive glass 141 and the second conductive glass 142 are both Indium tin oxide (ITO) transparent conductive glass. The first alignment film 143 is formed on the inner surface of the first conductive glass 141, and the second alignment film 144 is formed on the inner surface of the second conductive glass 142, both for determining the long axis extending direction of the liquid crystal molecules. Therefore, the liquid crystal molecules close to the first alignment film 143 are restrained by the first alignment film 143, and both tend to be parallel to the first conductive glass 141 and the second conductive glass 142. The liquid crystal molecules near the second alignment film 144 tend to be perpendicular to the first conductive glass 141 and the second conductive glass 142. Therefore, as shown in FIG. 4, the liquid crystal molecules in the liquid crystal cell 140 can be generally classified into two types, that is, liquid crystal molecules having a long axis perpendicular to the first liquid crystal layer 145 of the conductive glass and a second liquid crystal having a long axis parallel to the conductive glass. Liquid crystal molecules within layer 146.

The first compensation film 120 and the second compensation film 130 each have a three-dimensional spatial refractive property. The three-dimensional spatial refraction characteristics are often represented by n _x , n _y , n _z , where n _x and n _y represent the refractive index of the beam in the plane of the compensation film, and n _z represents the refractive index of the beam in the thickness direction of the compensation film. The first compensation film 120 generally adopts an A-type film, that is, n _x >n _y and n _y =n _z , and the second compensation film 130 generally adopts a C-type film, that is, n _x =n _y and n _y >n _z .

As shown in FIG. 5, the compensation effect of the first compensation film 120 on the first liquid crystal layer 145 is illustrated by taking the first liquid crystal layer 145 having a single liquid crystal molecule 149 as an example. The effect of the first compensation film 120 is approximately a virtual liquid crystal molecule 121 perpendicular to the liquid crystal molecules 149. The refractive index of the o-light of the virtual liquid crystal molecule 121 is larger than the refractive index of the e-light, and its influence on the rotational direction of the polarization direction of the linearly polarized beam is opposite to that of the liquid crystal molecule 149.

The display angle of view of the liquid crystal molecules 149 is within the angle θ of both sides of the long axis. Liquid The phase of the d1 segment of the linearly polarized beam 148 emerging outside the θ angle on both sides of the long axis of the crystal molecule 149 produces a certain retardation, thereby being converted into an elliptically polarized beam. When the elliptically polarized light beam enters the first compensation film 120, it will obtain the reverse compensation of the first compensation film 120 in the d2 segment, thereby converting into a primary linearly polarized light beam. Thus, the retardation produced by the linearly polarized beam 148 in the d1 segment of the liquid crystal cell 140 will result in its compensation of the d2 segment in the first compensation film 120, thereby adjusting its polarization direction.

Similarly, the retardation produced by the linearly polarized beam within the second liquid crystal layer 146 will also result in its compensation within the second compensation film 130, thereby adjusting its polarization direction.

The retardation produced by the linearly polarized beam within the liquid crystal cell 140 will result in its compensation within the first compensation film 120 and the second compensation film 130, thereby adjusting its polarization direction. Therefore, when the compensated linearly polarized light beam reaches the polarizing plate 110, it will be absorbed by the polarizing plate 110, and the generation of light leakage will be reduced.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above descriptions are only the preferred embodiments of the present invention, and those skilled in the art will be able to include equivalent modifications or variations in the spirit of the present invention.

100‧‧‧Reflective LCD

110‧‧‧ polarizer

120‧‧‧First compensation film

130‧‧‧Second compensation film

140‧‧‧Liquid Crystal Unit

141‧‧‧First conductive glass

142‧‧‧Second conductive glass

143‧‧‧First alignment film

144‧‧‧Second alignment film

145‧‧‧First liquid crystal layer

146‧‧‧Second liquid crystal layer

150‧‧‧reflection unit

Claims (8)

A reflective liquid crystal display comprising a polarizing plate and a liquid crystal cell, the liquid crystal cell comprising a first liquid crystal molecule having a long axis perpendicular to the polarizing plate, wherein the reflective liquid crystal display further comprises a long axis parallel to the a second liquid crystal molecule of the polarizing plate, a first compensation film, and a second compensation film, the first compensation film being located between the polarizing plate and the liquid crystal cell to compensate for a linearly polarized light beam caused by the first liquid crystal molecule With a phase delay, the second compensation film is located between the first compensation film and the liquid crystal cell to compensate for a phase delay caused by the second liquid crystal molecules to the linearly polarized beam. The reflective liquid crystal display of claim 1, wherein the refractive index of the o-light of the first compensation film is greater than the refractive index of the e-light. The reflective liquid crystal display of claim 1, wherein the three-dimensional spatial refractive index of the first compensation film satisfies a relationship of n _x > n _y and n _y = n _z . The reflective liquid crystal display of claim 1, wherein the reflective liquid crystal display further comprises a reflection unit, and the reflection unit and the second compensation film are respectively located at two sides of the liquid crystal unit. The reflective liquid crystal display of claim 4, wherein the liquid crystal cell comprises a first conductive glass and a second conductive glass, the first conductive glass is adjacent to the second compensation film, and the second conductive glass is adjacent to The reflecting unit. The reflective liquid crystal display of claim 5, wherein the liquid crystal cell comprises a first alignment film and a second alignment film, the first alignment film shape Formed on an inner surface of the first conductive glass, the second alignment film is formed on an inner surface of the second conductive glass. The reflective liquid crystal display of claim 1, wherein the refractive index of the o-light of the second compensation film is greater than the refractive index of the e-light. The reflective liquid crystal display of claim 1, wherein the second compensation film has a three-dimensional spatial refractive index satisfying a relationship of n _x = n _y and n _y > n _z .