KR100699158B1 - Liquid crystal display device, driving method thereof and mobile station having the same - Google Patents

Abstract

The liquid crystal display according to the present invention comprises a transflective liquid crystal panel without a color filter and a front light unit disposed on the front surface of the transflective liquid crystal panel and sequentially injecting red light, green light and blue light. The first display mode displays an image on the rear side of the transflective liquid crystal panel using red light, green light, and blue light sequentially incident from the light unit, and the transflective liquid crystal using red light, green light, and blue light sequentially incident from the front light unit. The feature is that the image is displayed in both directions of the second display mode of displaying the image on the front of the panel.

According to the liquid crystal display device according to the present invention, there is an advantage that the image can be displayed in both the front direction and the rear direction of the liquid crystal panel using one transflective liquid crystal panel.

Description

Liquid crystal display device, driving method thereof and mobile communication terminal having same

1 is a view conceptually showing the configuration of a liquid crystal display device according to the present invention;

FIG. 2 is a view illustrating an image displayed on a rear portion of a liquid crystal panel using light provided from a front light unit in the liquid crystal display according to the present invention.

3 is a view illustrating an image displayed on a front surface of a liquid crystal panel using light provided from a front light unit in the liquid crystal display according to the present invention.

4 is a view for explaining a data signal applied to a liquid crystal display device and a driving signal of a front light unit according to the present invention;

5A and 5B are views for explaining the difference in aperture ratio between a conventional liquid crystal display and a liquid crystal display according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100 ... Transflective Liquid Crystal Panel 110 ... First Substrate

111. Pixel electrode 113. Reflective layer

120 ... second substrate 121 ... black matrix

123 common electrode 130 liquid crystal layer

140 ... first polarizer 150 ... second polarizer

160 ... Front light unit 165 ... Light source

201R, 201G, 201B ... sub pixel

203 ... Black Matrix 210 ... Unit Pixel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device. In particular, a liquid crystal display device capable of displaying an image in both front and rear directions of a liquid crystal panel using one transflective liquid crystal panel, a driving method thereof, and a mobile communication including the same. It relates to a terminal.

In general, CRTs (or Cathode Ray Tubes) (CRTs) have been the most used screen display devices for displaying image information on the screen, which is bulky and heavy compared to the display area. Followed.

Accordingly, a thin film type flat panel display device having a small display area that can be easily used in any place even though the display area is large has been developed, and is gradually replacing the CRT display device. In particular, the liquid crystal display device has superior display resolution than other flat panel display devices, and exhibits a fast response speed as compared with CRTs when a moving image is realized.

As is known, the driving principle of the liquid crystal display device utilizes the optical anisotropy and polarization properties of the liquid crystal. Since the liquid crystal is thin and long in structure, the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal molecules having directionality and polarization in the molecular arrangement. Therefore, if the alignment direction is arbitrarily adjusted, light may be transmitted or blocked according to the alignment direction of the liquid crystal molecules by optical anisotropy of the liquid crystal, thereby displaying colors and images.

The active matrix liquid crystal display device adds an active element having a non-linear characteristic to each pixel arranged in a matrix form, and controls the operation of each pixel by using the switching characteristics of the element. Through this, the memory function is implemented.

On the other hand, in recent years, a variety of researches on a bidirectional display device (dual display) that can display the image in both the front and rear, the liquid crystal display device.

An object of the present invention is to provide a liquid crystal display device and a driving method thereof capable of displaying an image in both front and rear directions of a liquid crystal panel using one transflective liquid crystal panel.

In addition, another object of the present invention is to provide a thin mobile communication terminal capable of displaying images in both directions of a front side and a rear side by using a liquid crystal display device employing a transflective liquid crystal panel.

In order to achieve the above object, a liquid crystal display device according to the present invention includes a transflective liquid crystal panel in which a color filter is not formed; A front light unit disposed on the front surface of the transflective liquid crystal panel and configured to sequentially input red light, green light, and blue light; Its features are to include.

In addition, in order to achieve the above object, another example of the liquid crystal display device according to the present invention, the semi-transmissive liquid crystal panel without a color filter; A front light unit disposed on the front surface of the transflective liquid crystal panel and configured to sequentially input red light, green light, and blue light; And a first display mode for displaying an image on a rear portion of the transflective liquid crystal panel using red light, green light, and blue light sequentially incident from the front light unit, and red light sequentially incident from the front light unit. The display of the image in both directions of the second display mode for displaying the image on the front of the transflective liquid crystal panel using green light and blue light.

In addition, the liquid crystal display device driving method according to the present invention in order to achieve the above object, the semi-transmissive liquid crystal panel without a color filter; A front light unit disposed on the front surface of the transflective liquid crystal panel and configured to supply red light, green light, and blue light; A liquid crystal display comprising: a first display mode for displaying an image corresponding to one frame on a rear surface of the transflective liquid crystal panel using red light, green light, and blue light sequentially incident from the front light unit; It is characterized in that it drives in the second display mode in which an image corresponding to one frame is displayed on the front surface of the transflective liquid crystal panel using red light, green light, and blue light sequentially incident from the front light unit.

In addition, in order to achieve the above object, the mobile communication terminal according to the present invention is disposed on the front surface of the transflective liquid crystal panel and the transflective liquid crystal panel in which no color filter is formed, and sequentially inputs red light, green light and blue light. A liquid crystal display device having a front light unit; Communication means for performing communication with the outside; A control unit controlling image display of the communication means and the liquid crystal display device; Its features are to include.

According to the present invention, there is an advantage to provide a liquid crystal display device and a driving method for displaying an image in both the front direction and the rear direction of the liquid crystal panel using one transflective liquid crystal panel.

In addition, according to the present invention, by using a liquid crystal display device employing one transflective liquid crystal panel, there is an advantage that it is possible to provide a thin mobile communication terminal capable of displaying images in both directions of the front and rear parts.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view conceptually showing the configuration of a liquid crystal display according to the present invention.

As shown in FIG. 1, the liquid crystal display according to the present invention includes a transflective liquid crystal panel 100 and a front light unit 160 that provides light for displaying an image.

The liquid crystal display according to the present invention can display an image on the rear surface of the transflective liquid crystal panel 100 by driving the front light unit 160 provided on the front portion of the transflective liquid crystal panel 100. . In addition, the liquid crystal display according to the present invention may display an image on the front of the transmissive liquid crystal panel 100 by driving the front light unit 160 provided on the front of the transflective liquid crystal panel 100. Will be. Accordingly, the front and rear portions of the transflective liquid crystal panel 100 can display images in both directions.

In more detail, as shown in FIG. 2, the liquid crystal display according to the present invention uses the red light, green light, and blue light that are sequentially incident from the front light unit 160 of the transflective liquid crystal panel 100. The display apparatus may be driven in a first display mode for displaying an image on the rear surface. In this case, the first display mode is implemented by light transmitted through the pixel electrode 111 formed in the transflective liquid crystal panel 100.

In addition, the liquid crystal display according to the present invention, as shown in Figure 3, by using the red light, green light, blue light which is sequentially incident from the front light unit 160 to the front portion of the transflective liquid crystal panel 100 It may be driven in a second display mode for displaying an image. In this case, the second display mode is implemented by light reflected through the reflective layer 113 formed on the transflective liquid crystal panel 100.

In the present invention, a transflective liquid crystal panel 100 in which no color filter is formed is applied. And the front light unit 160 is provided with a light source 165, the light source 165 is configured to provide red light, green light, blue light. For example, the light source 165 may include a red light emitting device (LED), a green light emitting device (LED), and a blue light emitting device (LED), and a red cold cathode fluorescent lamp (CCFL) and a green cold cathode fluorescent lamp ( CCFL), and a blue cold cathode fluorescent lamp (CCFL).

In this way, the red light, the green light, and the blue light can be provided from the front light unit 160, so that the liquid crystal display according to the present invention can display a color image without a color filter. That is, by driving the red light, green light, and blue light provided from the front light unit 160 to be sequentially incident at a time interval, it is possible to implement an image of a desired color. The driving method of such a liquid crystal display will be described in more detail later.

The liquid crystal display device includes a first substrate 110, a second substrate 120, a liquid crystal layer 130, a first polarizer 140, and a second polarizer 150. Since details of each of the above components are already well known, only a brief description will be provided herein.

The first substrate 110 includes an array element having a thin film transistor, a pixel electrode 111 formed on the array element to transmit an incident light to display an image, and an insulating film formed on the pixel electrode 111. And a reflective layer 113 formed on a portion of the insulating film to reflect incident light to display an image. The reflective layer 113 may be formed of a material such as AlNd or Ag.

As an example, the case in which the reflective layer 113 is formed on the pixel electrode 111 is described. However, the pixel electrode 111 and the reflective layer 113 may be alternately formed on the array element. The arrangement and formation methods of the pixel electrode 111 and the reflective layer 113 are variously known, and since this is not a major concern in the present invention, detailed descriptions thereof will be omitted.

The array device may include a plurality of gate lines formed in a first direction, a plurality of data lines formed in a direction perpendicular to the gate line, a pixel region divided by the gate lines and data lines, and a plurality of gate lines and data lines. It comprises a thin film transistor formed in the intersection area. The semiconductor layer forming the thin film transistor may be formed of an amorphous silicon layer or a polycrystalline silicon layer. Since a lot of researches have already been performed on the process of manufacturing a thin film transistor using an amorphous silicon layer or a polycrystalline silicon layer, a description thereof will be omitted.

In addition, the second substrate 120 is provided at a position opposite to the first substrate 110, and the black matrix 121 is formed at a position opposite to the pixel electrode 111 of the first substrate 110. And a common electrode 123 formed under the black matrix 121 and / or the second substrate 120.

The liquid crystal layer 130 is filled between the first substrate 110 and the second substrate 120, and a first polarizing plate is disposed on the lower portion of the first substrate 110 and the upper portion of the second substrate 120. 140 and the second polarizing plate 150 are provided, respectively.

The polarizers 140 and 150 may include a 'Quarter-wave plate'.

A driving method of the liquid crystal display device having such a configuration will be described with reference to FIG. 4. 4 is a diagram for describing a data signal applied to a liquid crystal display and a driving signal of a front light unit according to the present invention.

In FIG. 4, the lighting time of the red light source, the green light source, and the blue light source of the front light unit for implementing the color image is shown in consideration of the response time of the liquid crystal panel. When the field sequential driving is applied, it is necessary to increase the time that the red light source, the green light source, and the blue light source are turned on in order to increase the brightness, so that the shorter the address time and the response time of the liquid crystal are advantageous.

However, since the address time, which is generally determined by the driving circuit and the resolution, is limited indefinitely, most field sequential driving methods are used in order to maximize the response speed of the liquid crystal. Therefore, in order for the image to be normally displayed through the field sequential driving, the response speed of the liquid crystal should be faster than 5.55 ms allocated to the subframe during the 180 Hz driving.

When such a field sequential driving method is applied, the red light source, the green light source, and the blue light source provided in the front light unit are sequentially driven. In this case, red light, green light, and blue light are incident to the liquid crystal panel by sequential driving of each light source, and then transmitted through the opening (pixel area) to sequentially implement red, green, and blue colors (first driving mode). If you do). The red, green, and blue colors implemented in the pixel region are formed at time intervals. These time intervals are referred to as fields, and thus, colors are sequentially driven by driving red, green, and blue light sources. The method is called a field sequential driving method.

Meanwhile, in the field sequential driving type liquid crystal display device, a frame applied to the conventional liquid crystal display device is divided into three fields, and red light, green light, and blue light are incident on the liquid crystal panel from the front light unit during each field. Typically, the time interval of one frame of the liquid crystal display driving at 60 Hz is 16.7 ms (1/60 s). Therefore, the field of the field sequential driving method has a time interval of 5.55 ms (1/180 s). This time interval is a very short time, and field changes in this short time interval cannot be detected by the human eye. Eventually, the human eye is recognized as an integrated time of 16.7 ms, so that the combined colors of red, green, and blue can be recognized.

As described above, the liquid crystal display according to the present invention includes a light source for emitting red light, green light, and blue light, respectively, so that a color image can be realized without employing a color filter. Therefore, according to the present invention, by displaying an image by applying a liquid crystal panel that is not provided with a color filter, the light absorption phenomenon by the color filter does not occur it is possible to implement a high brightness image.

In the liquid crystal display according to the present invention, since the color filter is not formed, the color image display and the black and white image display may be selectively implemented. That is, when the front light unit is not driven, the black and white image may be displayed by a reflection mode using external natural light, and the color image may be displayed by driving the front light unit. The display device of both color and monochrome images can be used in black and white when displaying low density information and in color when displaying high density information. By selecting the mode appropriately, longer use is possible.

In addition, according to the present invention, since the unit pixel is not divided into sub-pixels of R, G, and B, the aperture ratio can be improved and a high resolution image can be realized. This will be described with reference to FIGS. 5A and 5B. 5A and 5B illustrate a difference in aperture ratio between a conventional liquid crystal display and a liquid crystal display according to the present invention.

That is, in the conventional liquid crystal display device employing a color filter, as shown in Fig. 5A, three sub pixels 201R, 201G, and 201B displaying red, green, and blue are gathered to form one unit pixel. In addition, a black matrix 203 is formed between the sub pixels 201R, 201G, and 201B. However, in the liquid crystal display device according to the present invention, as shown in FIG. 5B, a unit pixel having a single structure can be formed without red, green, and blue sub pixels and a black matrix. As described above, in the liquid crystal display according to the present invention, the aperture ratio may be further improved, and as the degree of freedom for reducing the size of the unit pixel is extended, the liquid crystal display having high resolution may be more easily designed.

In addition, according to the present invention, the number of driving elements can be reduced by driving the unit pixels corresponding to the conventional R, G, and B sub pixels instead of driving each of the R, G, and B sub pixels.

On the other hand, the liquid crystal display having such a configuration can be utilized as a double-sided display device. Accordingly, when the liquid crystal display device according to the present invention is applied to a mobile communication terminal (mobile portable communication, PDA, etc.), it is possible to display images in both directions of the front part and the rear part of the liquid crystal panel. The video display function can be implemented.

 For example, when the liquid crystal display device according to the present invention is applied to a mobile communication terminal equipped with a digital camera function, several users can simultaneously view a picture screen of the same screen size and the same resolution in both directions of the mobile communication terminal. There is usefulness to become.

As described above, according to the liquid crystal display and the driving method thereof, there is an advantage in that an image can be displayed in both directions of the front direction and the rear direction of the liquid crystal panel using one liquid crystal panel.

In addition, according to the present invention, by displaying an image by applying a liquid crystal panel that is not provided with a color filter, there is an advantage that a light absorption phenomenon due to the color filter does not occur to implement a high brightness image.

In addition, according to the present invention, since the unit pixel is not divided into sub-pixels of R, G, and B, the aperture ratio is improved, and the high resolution image can be realized.

In addition, according to the present invention, the number of driving elements of the data line is reduced to 1/3 by driving the unit pixels corresponding to the conventional R, G, and B sub pixels instead of driving the respective sub pixels of R, G, and B. There are advantages to it.

In addition, according to the mobile communication terminal according to the present invention, by using a liquid crystal display device employing one liquid crystal panel, there is an advantage that it is possible to provide a thin mobile communication terminal capable of displaying images in both directions.

Claims (20)

A transflective liquid crystal panel in which a color filter is not formed; A front light unit disposed on the front surface of the transflective liquid crystal panel and configured to sequentially input red light, green light, and blue light; Liquid crystal display comprising a. A transflective liquid crystal panel in which a color filter is not formed; A front light unit disposed on the front surface of the transflective liquid crystal panel and configured to sequentially input red light, green light, and blue light; It is configured to include, First display mode for displaying an image on the back of the transflective liquid crystal panel using red light, green light, and blue light sequentially incident from the front light unit, and red light, green light, and blue light sequentially incident from the front light unit. And displaying an image in both directions of a second display mode for displaying an image on a front surface of the transflective liquid crystal panel. The method according to claim 1 or 2, The front light unit includes a red light source, a green light source and a blue light source. The method according to claim 1 or 2, The front light unit includes a red light emitting device, a green light emitting device, and a blue light emitting device. The method according to claim 1 or 2, The front light unit includes a red cold cathode fluorescent lamp (CCFL), a green cold cathode fluorescent lamp (CCFL), and a blue cold cathode fluorescent lamp (CCFL). The method according to claim 1 or 2, The transflective liquid crystal panel, A first substrate comprising an array element having a thin film transistor, a pixel electrode formed on the array element to transmit an incident light to display an image, and a reflective layer to reflect the incident light to display an image; A second substrate provided at an opposite position of the first substrate and having a black matrix formed between the pixel electrodes of the first substrate; A liquid crystal layer filled between the first substrate and the second substrate; Liquid crystal display comprising a. The method of claim 6, The array device, A plurality of gate lines formed in a first direction; A plurality of data lines formed in a direction perpendicular to the gate line; A pixel region divided by the gate line and the data line; A thin film transistor formed at an intersection of the gate line and the data line; Liquid crystal display comprising a. The method of claim 6, The reflective layer is formed of AlNd or Ag. The method according to claim 1 or 2, The transflective liquid crystal panel has a response speed characteristic faster than 5.55ms. The method according to claim 1 or 2, And the semiconductor layer formed on the transflective liquid crystal panel comprises an amorphous silicon layer or a polycrystalline silicon layer. The method according to claim 1 or 2, And a polarizing plate is further provided on the front and rear surfaces of the transflective liquid crystal panel, respectively. The method according to claim 1 or 2, The image is displayed on the front surface of the transflective liquid crystal panel by using the light reflected from the reflective region of the transflective liquid crystal panel, and the light is transmitted through the transmissive region of the transflective liquid crystal panel. LCD, characterized in that for displaying an image on the back. The method according to claim 1 or 2, And a color image by using light provided from the front light unit, and a black and white image by using light incident from an external light source. The method of claim 11, The polarizing plate comprises a 'Quarter-wave plate'. A transflective liquid crystal panel in which a color filter is not formed; A front light unit disposed in front of the transflective liquid crystal panel and configured to supply red light, green light, and blue light; In the liquid crystal display device comprising a, A first display mode for displaying an image corresponding to one frame on the rear surface of the transflective liquid crystal panel using red light, green light, and blue light sequentially incident from the front light unit, and red light sequentially incident from the front light unit. And driving in a second display mode in which an image corresponding to one frame is displayed on a front surface of the transflective liquid crystal panel using green light and blue light. The method of claim 15, The front light unit includes a red light source, a green light source, and a blue light source. The method of claim 15, And the transflective liquid crystal panel has a response speed characteristic faster than 5.55 ms. The method of claim 15, The red light, the green light, and the blue light provided from the front light unit are sequentially incident with each other at a time interval to implement one image frame. The method of claim 15, And displaying a color image by using light provided from the front light unit, and displaying a black and white image by using light incident from an external light source. The liquid crystal display device according to claim 1 or 2; Communication means for performing communication with the outside; A control unit controlling image display of the communication means and the liquid crystal display device; Mobile communication terminal comprising a.

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