KR101529649B1 - Field sequential display method liquid crystal display apparatus - Google Patents

Abstract

The present invention discloses a time-division display method and a liquid crystal display device. The time division display method is a time division display method of time-divisionally displaying an input image frame in a plurality of subframes so that an image can be displayed at a frequency higher than a frame frequency of an input video signal. The time division display method is divided into a plurality of regions, And controlling the plurality of areas of the display panel to be driven for respective different time intervals within one frame time, the frame time including at least two time intervals. Accordingly, the driving time of the signal applied to the pixels of the display device is adjusted to perform the 120 Hz time division driving which is written twice for one frame, thereby obtaining the 240 Hz time division driving effect.

Description

FIELD SEQUENTIAL DISPLAY METHOD LIQUID CRYSTAL DISPLAY APPARATUS [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a display method, and more particularly, to a liquid crystal display device and a time division display method capable of improving a side image quality in a VA (Vertical Alignment) mode.

In recent years, most of flat panel TV display products are adopting LCD technology, and high-definition TV LCD products adopt one of a horizontal electric field mode (IPS mode) and a vertical orientation mode (VA mode). In the IPS mode, the liquid crystal molecules have an initial orientation parallel to the substrate surface, and the liquid crystal molecules in the horizontal orientation are rotated in the azimuth angle direction by the horizontal electric field generated by the electrodes formed on one substrate, Thereby controlling the polarization of the light. On the other hand, the VA mode initially has a liquid crystal molecular orientation perpendicular to the substrate. When a voltage is formed between the electrodes on both substrates, the liquid crystal rotates in a polar angle direction to induce the movement of the optical axis of the liquid crystal layer, .

Both IPS and VA modes have been developed as key technologies for high-definition LCD technology. Overcoming the narrow viewing angle problem of TN (Twisted Nematic) technology, which is mainly used in monitors and notebooks, I cry. However, the IPS technology has a wide viewing angle characteristic in principle, whereas the VA mode itself does not have a wide viewing angle characteristic. Thus, all VA mode products employ a multi-domain structure and optical compensation films. The adoption of multi-domain technology and optical compensation film technology has resulted in considerable improvement in viewing angle, but still has the problem of dimming of color on the side. For this reason, the VA mode mostly employs a pixel division technique in which one pixel is divided into two sub-pixels and a different voltage is applied to each pixel. The pixel segmentation technology is very helpful for improving the picture quality of the VA mode products.

The VA mode adopts the pixel segmentation technique to improve the side image quality. The pixel division technique has the problems that the number of signal transmission lines (bus-lines) increases, the number of TFTs increases, and the aperture ratio, which is an effective area of pixels, decreases because each pixel is divided into two sub-pixels and driven. This results in problems such as an increase in the manufacturing cost of the LCD and an increase in power consumption due to the reduction of the transmittance.

In addition, unlike the pixel division technique, the side view visibility improvement technique using time division using the conventional high-speed driving does not have a problem of decreasing the aperture ratio or complicating the panel structure. However, the time division technique requires high- . In particular, high-speed driving at 240 Hz requires four times as much data and four times faster driving speed than the conventional 60 Hz driving. Although it is possible to perform time division only by 120Hz drive, it is difficult to show the effect because the side viewability improvement is insignificant only by 120Hz drive.

It is an object of the present invention to solve the above-mentioned problems and it is an object of the present invention to provide a display device capable of achieving an effect of 240 Hz time division using a driving technology of 120 Hz without requiring an unreasonable cost rise to improve picture quality, A time-division display method, and a liquid crystal display device.

It is another object of the present invention to provide a time division display method and a liquid crystal display device for sensing a temperature of a display device and applying a compensation value for an image signal according to a temperature to perform time division.

According to an aspect of the present invention, there is provided a time division display method for time-divisionally displaying an input image frame in a plurality of subframes so as to display an image at a frequency higher than a frame frequency of an input video signal, Controlling each of the plurality of regions of the display panel divided into a plurality of regions to be independently driven to be driven for each of different time intervals within one frame time, the frame time including at least two time intervals .

The time-divisional display method may further include displaying the sub-frame based on the controlled signal.

Dividing the input image frame into a first sub-frame and a second sub-frame, time-dividing the one frame time into four frame time intervals, and dividing the one frame time into first to fourth quadrant frame time intervals, Wherein the first region is spatially divided into a first region and a second region and is independently displayed, wherein the first region is driven in first and second quadrant frame time periods, and the second region is divided into third and fourth quadrant frame time periods Lt; / RTI >

The first region may correspond to an odd-numbered line of a gate line of the display panel, and the second region may correspond to an even-numbered line of a gate line of the display panel.

Wherein the first area and the second area perform at least two times of division driving during the respective driving time periods, and the time at which different time division signals applied to the respective pixels included in the respective areas are displayed is one frame time As shown in FIG.

The time for displaying different time-division signals applied to each pixel of each area may be displayed at a ratio of 1: 3 based on one frame time.

Wherein the first area is displayed as a first control signal during a first quadrant frame time interval and is displayed as a second control signal for a remaining quadrant frame time period except for the first quadrant frame time period, Area may be displayed as a third control signal during the third quadrant frame time period and may be displayed as the fourth control signal for the remaining quadrant frame time periods except for the third quadrant frame time.

Wherein each pixel of the first area is displayed at a different gradation when displayed by the first control signal and the second control signal, and each pixel of the second area displays the third control signal and the fourth control signal , They can be displayed at different gradations.

Wherein the controlling step includes the steps of classifying an input image frame into an L region having a gradation lower than a first gradation, an M region having a higher gradation than the first gradation, lower than a second gradation, and an H region having a gradation higher than the second gradation based on the gradation of the input image frame; And controlling the L, M, and H regions to be driven with different sub-frame signals and different gradations.

(i) the L region is controlled to be displayed in a gradation varying from 0 to 255 in the first quadrant frame time interval and a gradation of 0 in the remaining quadrant frame time period, and (ii) (Iii) the H region is controlled so as to have a gradation varying from 0 to 255 in the first quadrant frame time period, and a remaining quadrant in the second quadrant frame time period, It is possible to control the display to be performed at the gray level of 255 in the frame time period to be performed.

The subframe data that is substantially applied to the display panel in the quadrant frame time interval allocated for driving the respective regions of L, M, and H may be controlled to increase or decrease as the gradation of the input signal increases.

According to an aspect of the present invention, there is provided a liquid crystal display device for time-divisionally displaying an input image frame in a plurality of subframes so as to display an image at a frequency higher than a frame frequency of an input image signal, A display panel divided into a plurality of regions and independently driven; And a controller for controlling the plurality of areas of the display panel to be driven for different time intervals within one frame time, the frame time including at least two time intervals.

Wherein the liquid crystal display device comprises: a data driver for generating an analog image signal based on a control signal of the controller and providing the analog image signal to a pixel of the display panel; And a gate driver for sequentially generating scan pulses based on the control signal and supplying the generated scan pulses to a gate line, wherein a shift register structure is provided so that the even line wiring and the odd line wiring of the gate line can be driven separately Lt; / RTI >

Dividing the input image frame into a first sub-frame and a second sub-frame, time-dividing the one frame time into four frame time intervals, and dividing the one frame time into first to fourth quadrant frame time intervals, Wherein the first region is spatially divided into a first region and a second region and is independently displayed, wherein the first region is driven in first and second quadrant frame time periods, and the second region is divided into third and fourth quadrant frame time periods Lt; / RTI >

Wherein the first area and the second area perform time division driving at least twice during the respective driving time periods, and the time at which different time division signals applied to the respective pixels included in the respective areas are displayed is one frame time As shown in FIG.

Wherein the controller is configured to classify an L region having a lower gray level than the first gray level, an M region having a higher gray level than the first gray level and an H region having a higher gray level than the second gray level based on the gray level of the input image frame, ; And the L, M, and H regions may be controlled to be driven with different sub-frame signals and different gradations.

According to an aspect of the present invention, there is provided a time division display method for dividing an input image frame into a plurality of subframes so as to display an image at a frequency higher than a frame frequency of an input video signal, Generating a compensation value of the input video signal by applying a signal change to the input video signal in consideration of a temperature value; Dividing the signal into a plurality of subframe signals based on a compensation value of the video signal; And displaying the time-divided sub-frame signal.

The compensation value generation step may include sensing a temperature inside and outside of the display device; And generating the compensation value based on the sensed temperature.

The compensation value may include at least one of a luminance compensation value, a gamma compensation value, and a contrast compensation value depending on a temperature.

And controlling the plurality of regions of the display panel, which are divided into a plurality of regions and independently driven, to be driven during different periods within one frame time, respectively.

According to an aspect of the present invention, there is provided a liquid crystal display device for dividing an input image frame into a plurality of subframes so as to display an image at a frequency higher than a frame frequency of an input image signal, A compensation value generation unit for generating a compensation value of the input image signal by applying a signal change to the input image signal in consideration of a temperature value; A time division unit that time-divides the signal into the plurality of subframe signals based on the compensation value of the video signal; And a panel for displaying the time-divided sub-frame signal.

According to the time division display method and the liquid crystal display device of the present invention, the driving time of the 240 Hz time division can be obtained by performing the 120 Hz time division driving which is written twice for one frame by adjusting the time of the signal applied to the pixel of the display device.

In addition, according to the time-division display method and the liquid crystal display device of the present invention, a compensation value is applied to an image signal according to a temperature to enable a user to view an image with an optimal image quality suitable for a current temperature, and to reduce the incidence of crosstalk .

1 is a block diagram schematically showing a liquid crystal display device according to an embodiment of the present invention,
2 is a diagram for explaining a 240 Hz time division driving method and a 120 Hz time division driving method,
FIG. 3 is a graph for showing the level of lateral visibility according to the 240 Hz time division driving method and the 120 Hz time division driving method,
4 is a table showing the visibility index according to the 240 Hz time division driving method and the 120 Hz time division driving method,
5 is a view illustrating a panel structure of a liquid crystal display device according to an embodiment of the present invention.
6 is a view for explaining a driving principle of a time division display method according to an embodiment of the present invention;
7 is a detailed block diagram specifically showing a controller of a liquid crystal display device according to an embodiment of the present invention,
FIG. 8 is a graph illustrating a side view level according to the time division display method according to an embodiment of the present invention,
9 is a table showing the visibility index according to the time division display method according to the embodiment of the present invention,
10 is a block diagram schematically showing a liquid crystal display device according to another embodiment of the present invention,
11 is a detailed block diagram specifically illustrating a compensation value generating unit of a liquid crystal display device according to another embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a block diagram schematically illustrating a liquid crystal display device according to an embodiment of the present invention. 1, a liquid crystal display device according to an exemplary embodiment of the present invention may include a controller 10, a data driver 20, a gate driver 30, and an LCD panel 40. Referring to FIG.

Referring to FIG. 1, the controller 10 receives an input signal Gi, performs time division, and generates a driving signal for driving the panel 40. The controller 10 includes a timing controller (not shown), and the timing controller time-divides the input image frame into two or more subframes at a frame frequency. That is, a video signal associated with a pixel of each subframe is divided into subframes.

According to the embodiment of the present invention, in a method of displaying an input video signal Gi, the controller 10 can generate a video signal having a plurality of sub-frames within each frame, have. At this time, the controller 10 may divide the input video signal Gi into two, three, or four. From the viewpoint of the side view, it is preferable to have four subframes because the side image quality increases as the number of subframes increases. In the case of having four subframes, an image frame of 60 Hz can be divided into 240 Hz subframes, and the input image signal Gi can also be divided into respective image signals in each subframe. However, when the subframe is divided into subframes of 240 Hz, the controller 10 must have a further configuration for high-speed driving, and a high-specification configuration must be added to the panel 40 in order to receive and drive an image signal of 240 Hz.

The controller 10 may use a method of interpolating selected two frames by selecting consecutive input frames during frame division and video signal division.

In addition, the controller 10 may generate a gradation data signal by applying a different lookup table according to the pixel position of each subframe after the time division operation, and output the gradation data signal. That is, the data driver 20 and the gate driver 30 generate a data driving control signal and a gate driving control signal, respectively, and transmit the data driving control signal and the gate driving control signal to the data driving unit 20 and the gate driving unit 30, respectively.

The data driver 20 provides a constant voltage to the pixel based on the data driving control signal received from the controller 10. [ The data driver 20 receives the gamma voltage according to the image signal from the gray-scale voltage generator (not shown) and provides the gamma voltage to the pixels of the LCD panel 40. The data driver 20 converts the received image signal into an analog image signal and transmits the analog image signal to the data line formed in the LCD panel 40. [

The gate driver 30 receives the gate driving control signal supplied from the controller 10, sequentially generates scan pulses and supplies the generated scan pulses to the gate lines. According to the embodiment of the present invention, the gate driver 30 sequentially supplies scan pulses to the gate lines during the driving period of the odd-numbered subframe of the subframe in which the frame frequency is increased by the timing controller, A scan pulse can be supplied to the gate line during the driving period of the frame. Further, the gate driver 30 turns on or off the TFT of the LCD panel 40 in accordance with the scan pulse.

The LCD panel 40 receives an analog image signal and a scan pulse from the data driver 20 and the gate driver 30 through a data line and a gate line and transmits a signal to each pixel in the panel to display an image . The LCD panel 40 can display an image at a frame frequency of 2 to 4 times by dividing a video signal of an input frame. For example, an image can be displayed at a high frame rate of 120 Hz to 240 Hz.

In the embodiment of the present invention, the LCD panel 40 may be constituted by injecting liquid crystal between two glass substrates. On the lower glass substrate of the LCD panel 40, the data lines and the gate lines are orthogonalized. A TFT (Thin Film Transistor) may be formed at an intersection of the data line and the gate line. The TFT supplies data on the data line to the liquid crystal cell in response to the stanch pulse. The gate electrode of the TFT is connected to the gate line, and the source electrode of the TFT can be connected to the data line.

2 is a view for explaining a 240 Hz time division driving method and a 120 Hz time division driving method.

Referring to FIG. 2, in the 240 Hz time division scheme, when an input signal is input at 60 Hz, a frame time is divided into four subframes, and an image signal for each pixel is converted into four subframe signals. The output signals applied to the panel 40 are Gi -> (Ga, Gb, Gc, Gd) and Gb - Gb when the input gradation is Gi and each subframe is defined as F_a, F_b, F_c, Are separated into four signals as shown in FIG.

At this time, it can be divided into four regions (A, B, C, D) based on the range of 0 to 255 according to input gradation. The gradation corresponding to each area is as follows.

The gradation of each sub-

The second to fourth subframes F_b, F_c, and F_d (0 to 255, 0, 0, 0) have variable grayscales ranging from 0 to 255 in the first subframe F_a, ) Means that the gradation is 0.

B area: (255, 0 to 255, 0, 0)

C region: (255, 255, 0 to 255, 0)

D region: (255, 255, 255, 0 to 255).

According to the embodiment of the present invention, the area of the input signal can be divided into 0 to 120 gray, 120 to 180 gray, 180 to 230 gray, and 230 to 240 gray for the A region and the D region, respectively . This is an embodiment, and is not necessarily limited thereto.

On the other hand, the 120 Hz driving method divides the input frame into two areas and displays it. Therefore, the input frame is divided into two subframes. Referring to FIG. 2, F_p and F_q correspond to subframes. The input signal Gi is divided into two subframe signals and can be expressed as Gi -> (Gp, Gq) with respect to the gradation. (For example, P: 0 to 180 gray, Q: 180 to 255) by dividing the input signal Gi into two regions and dividing the input signal Gi into four regions (A, B, C and D) gray -> this can be determined through experimentation and is not necessarily limited to this embodiment). The gray level of each region can be represented by the P region (0 to 255, 0) and the Q region (255, 0 to 255). Therefore, an arbitrary input signal Gi is separated into (Ga, Gb, Gc, Gd) at 240 Hz and separated into (Gp, Gq) at 120 Hz. At this time, And there is only one Gp and Gq in the case of not 0 or 255 gradation.

FIG. 3 is a graph illustrating the side visibility level according to the 240 Hz time division driving method and the 120 Hz time division driving method. In the case of performing the time division by the above-described method, simulation of the side view visibility was tried through evaluation of a test cell.

As shown in FIG. 3, the gamma curve of the side surface shows a large difference when compared with the gamma curve of the front surface. The larger the difference from the frontal gamma, the less the side visibility is. In the case of the 240 Hz drive, the curve is the most similar to the gamma curve in the front view. In the case of the 120 Hz drive, the performance is similar to that in the case where the time division is not applied. It can be seen that the lowest side visibility in the area A is shown by the area.

4 is a table showing the visibility index according to the 240 Hz time division driving method and the 120 Hz time division driving method. It is difficult to judge the visibility level by the shapes of the two side gamma curves of FIG. 3, but the level of the side visibility can be more clearly understood by calculating it using the side viewability index calculation method. The lateral visibility calculation is described in the paper ("Assessment of Image Quality Degraded by Tone Rendering Distortion", JK Song and SB Park, Journal of Display Technology, Vol.7, No. 7, pp. 365-372, . When the index is calculated according to the above method, the lower the calculated index value, the better the image quality.

Referring to FIG. 4, in the case of the general method, the visibility index is 0.401, and the 240Hz driving is 0.266 and the 120Hz driving is 0.345, which is lower than that of the general method. However, 120Hz is 240Hz Which is significantly lower than that of the first embodiment. The reference value of the pixel division method exhibits a visibility of about 0.24 to 0.27 level. Compared with this, the 240 Hz time division exhibits a level of visibility similar to that of the pixel division, but the level of visibility at 120 Hz has an inferior level of visibility. That is, the time division method shows a lower index value than the general method, which means improvement of the side viewability. However, since the side visibility level in the time division structure depends sensitively on the frame frequency, 120 Hz time division has insufficient characteristics Able to know.

5 is a view illustrating a panel structure of a liquid crystal display device according to an embodiment of the present invention. Referring to FIG. 5, the liquid crystal display device of the present invention includes a structure in which the panel is divided into two parts and can be separately driven. However, this is only an embodiment, and is not necessarily limited to this. That is, according to another embodiment of the present invention, the apparatus may include a structure in which the panel is divided into three or four or more regions and can be separately driven.

Referring to FIG. 5, the pixels 502 arranged in the even line 512 and the pixels 514 arranged in the odd line 514 may be separately driven. However, it is not always necessary to drive the odd-numbered line 512 and the even-numbered line 514 separately, but they may be separately driven in different ways. In order to drive them separately, it is necessary to arrange the signal generating circuit of the gate separately. The odd gate signal generating circuit 522 and the even gate signal generating circuit 524 are separately constructed so that the odd gate signal generating circuit 522 is connected to the odd line 512 and the even line 514 is connected And transmits the signals provided to the pixels of the odd line 512. The even gate signal generating circuit 524 is connected only to the even line 514 and the odd line 512 is not connected and carries signals provided to the pixels of the even line 514. [

According to an embodiment of the present invention, a panel structure may be formed such that the gate lines of the odd-numbered lines 512 and the gate lines of the even-numbered lines 514 are separately driven with separate shift resister structures. The above structure can be implemented by a method of integrating a gate chip on a glass using amorphous silicon gate (ASG) technology in the panel.

6 is a view for explaining a driving principle of a time division display method according to an embodiment of the present invention. As shown in Fig. 6, odd-numbered lines and even-numbered lines are driven as separate sub-frame signals.

Referring to FIG. 6, a method of applying a signal to two portions (in this embodiment, divided into odd-numbered lines and even-numbered lines) first divides each frame into two subframes of the first half and the second half of the frame . This can be defined as an Fe subframe (odd line) and an Fo subframe (even line). Only the odd lines are driven during the Fe sub-frame (odd lines), and only the even lines are driven during the Fo sub-frames (even lines).

Based on the 120 Hz driving standard, one subframe time can be defined as a time when the entire panel can be turned on once. However, if only the odd line is driven, it can be said that the driving can be repeatedly performed twice during one subframe time. Thus, odd lines are driven twice consecutively during the first half of the Fe sub-frame time. And the even line is driven twice in succession for the Fo subframe time of the latter half. When receiving the input signal Gi, the odd-numbered pixels are divided into four sub-frames Fe_a, Fe_b, Fe_b and Fe_b to generate signals (Gea, Geb, Geb and Geb) The results are similar to those obtained. In this case, it can be said that the actual data is applied during the previous two subframe times and the second applied Geb data is maintained during the latter two subframes. Therefore, the odd line is driven by receiving two data, so that the effect of having four subframes can be obtained. However, as described above, different signals may be transmitted and displayed at a ratio of 1: 3, but the ratio is not necessarily limited to 1: 3, and other asymmetric ratios can be applied. That is, in this case, the actual signal is applied to the preceding two quadrant frame time periods, and the signal applied during the second quadrant frame time period is maintained in the two quadrant frame time periods.

On the other hand, when the pixels of the even lines receive the Gi signal, signals (Gob, Gob, Goa, Gob) are applied to the four subframes Fo_b, Fo_b, Fo_a and Fo_b. That is, the actual data is applied only during the last two subframe times of the four subframe times, and the Fo_b signal applied to the last subframe of the previous frame is maintained during the two subframe times of the first half.

In the time-divisional display method according to an embodiment of the present invention, the number of data generated in an actual timing controller (not shown) corresponds to 120 Hz driving which is twice the input signal Gi. Thus, writing is performed twice for each pixel during each frame time. However, unlike typical 120Hz drive (see Fig. 2), the writing time difference is different. In other words, when one frame time is divided into four subframe times, a signal such as (Gp, Gp, Gq, Gq) is applied to a general 120Hz time division driving, but the 120Hz time division driving according to the embodiment of the present invention is , Geb, Geb, Geb) are input. For example, when Gea = 0 to 255 and Geb = 0 are input, the same signal is applied as in the driving method of the A region of 240 Hz. On the other hand, when Gea = 0 to 255 and Geb = 255, the same signal as the D region of 240 Hz is applied. Therefore, while driving at 120 Hz, the A region and the D region of 240 Hz can be imitated equally, and the grayscale corresponding to the regions B and C can be configured by appropriately adjusting Gea and Geb.

7 is a detailed block diagram illustrating a controller of a liquid crystal display device according to an exemplary embodiment of the present invention. 7, the controller 700 of the liquid crystal display device may include an area classification unit 710 and a drive control unit 720 according to an embodiment of the present invention.

Referring to FIG. 7, the region classifying unit 710 classifies the input image frame into three regions based on the gray level of the input image frame. This can be defined as the L, M, and H regions. The L region is a region having a low gradation below a certain standard, the M region is a region having an intermediate gradation, and the H region is an region having a gradation higher than a specific standard. Comparing this with each region of 240 Hz, the L region is the same as the A region, the H region is the same as the D region, and the M region includes the B and C regions. If the input gradation is lower than the first gradation and is higher than the first gradation and lower than the second gradation, the region classifying unit 710 classifies the gradation of the input image into the M region and the H region if the gradation is higher than the second gradation Classify.

The driving control unit 720 controls the L, M, and H regions classified by the region classifying unit 710 to be driven with different sub-frame signals and different gradations. Describing this with reference to an odd line, the L region is driven to (0 to 255, 0, 0, 0). At this time, the first subframe data increases as Gi increases. The M region is driven with 0 to 255, 0 to 255, 0 to 255, 0 to 255, where the first subframe data decreases as Gi increases, and the second 0 to 255 increases as Gi increases . Data such as (0, 255, 255, 255) is applied when the last gradation of the M area is reached. (0 to 255, 255, 255, 255) in the H region, and the first subframe data increases as the gray level increases.

8 is a graph illustrating a side view level according to the time division display method according to an embodiment of the present invention. As shown in FIG. 8, when the time-division effect is verified through simulation using the 120 Hz driving method of the present invention, similar results are obtained except for the center M region when compared with 240 Hz. That is, the relative brightness in the aspect of the new 120 Hz time division driving method is almost similar to the side of 240 Hz, and thus, the side visibility is improved.

9 is a table showing the visibility index according to the time division display method according to an embodiment of the present invention. As shown in FIG. 9, it can be seen from the table that the 120 Hz driving method of the present invention exhibits a visibility index substantially similar to 240 Hz time division, which is comparable to the pixel division method Good side visibility can be seen.

10 is a block diagram schematically showing a liquid crystal display device according to another embodiment of the present invention. 10, the liquid crystal display device according to another embodiment of the present invention may include a compensation value generating unit 1010, a time partitioning unit 1020, and a panel 1030. [

The conventional temperature compensation method according to the time division method follows a method in which values of the sub-frames Ga, Gb, Gc and Gd are compensated according to the temperature when the input signal Gi is inputted. That is, the subframes of Ga, Gb, Gc, and Gd all had to be transformed into optimized signal values through a series of compensation processes, which had to go through very complicated signal processing algorithms.

Referring to FIG. 10, a liquid crystal display device according to another embodiment of the present invention provides an algorithm for placing a preprocessing component of a compensation value generator 1010 to improve the above complexity.

The compensation value generation unit 1010 applies a signal change to the input signal Gi in consideration of a temperature value to generate a compensation value of Gi '. The compensation value Gi 'may be directly calculated by a specific calculation method, and may be generated by extracting a compensation value matching a specific temperature with reference to the lookup table 1012. [ The lookup table is made up of a compensation value corresponding to the internal or external temperature in the form of a table. The lookup table is stored in a memory (not shown) of the liquid crystal display device. The compensation value Gi 'may include at least one of a luminance compensation value, a gamma compensation value and a contrast compensation value. The compensation value Gi 'is divided into two to four subframe signals by the time division unit 1020 and input to the panel 1030. [ In this way, since many logic values for changing Gi to Gi 'are added without generating compensating values of Ga, Gb, Gc, and Gd, respectively, the entire configuration is greatly simplified.

11 is a detailed block diagram specifically illustrating a compensation value generating unit of a liquid crystal display device according to another embodiment of the present invention. 11, the compensation value generator 1010 according to an embodiment of the present invention may include a temperature sensing unit 1110 and a calculation unit 1120. [

Referring to FIG. 11, the temperature sensing unit 1110 senses an external temperature or an internal temperature. The temperature sensing unit 1110 measures the internal temperature of the liquid crystal display device. The temperature sensing unit 1110 can measure the temperature of various portions of the liquid crystal display device. For example, the temperature at the front or back of the device can be measured. The temperature sensing unit 1110 measures the temperature outside the liquid crystal display device. In this case, the sensor included in the temperature sensing unit 1110 can be mounted directly on the outside. Accordingly, the temperature sensing unit 1110 may operate as a separate sensor connected by wire or wirelessly.

The calculation unit 1120 generates a compensation value based on the sensed temperature. The calculation unit 1120 may generate a compensation value by referring to a plurality of lookup tables 1120 in which image quality compensation values according to an external temperature and an internal temperature are recorded. The lookup table may include at least one of a luminance compensation value for each of the internal temperature and the external temperature, a gamma compensation value, and a contrast compensation value. The calculating unit 1120 extracts a lookup table corresponding to the external or internal temperature. The calculating unit 1120 applies image quality compensation to the image using the extracted lookup table. The calculating unit 1120 may generate the direct compensation value using a specific algorithm for calculating the compensation value according to the sensed temperature. In this case, an algorithm for calculation is stored in a memory (not shown).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions as defined by the following claims It will be understood that various modifications and changes may be made thereto without departing from the spirit and scope of the invention.

Claims (6)

A time division display method for time-divisionally displaying an input image frame in a plurality of subframes so that an image can be displayed at a frequency higher than a frame frequency of an input video signal,
The pixels of the first area among the plurality of areas of the display panel divided into a plurality of areas and driven independently are driven only in a first sub-frame time period of one frame section, and pixels of the second area are driven by the first area Frame period, and the control step is performed so as to be driven only in the second sub-frame time period
Dividing the input image frame into an L region having a gray level lower than a first gray level, an M region having a gray level higher than the first gray level, lower than a second gray level, and a higher gray level than the second gray level; And
And controlling the L, M, and H regions to be driven with different sub-frame signals and different gradations.
The method according to claim 1,
(i) the L-th frame is divided into a first quadrant frame time period-quadrant frame time period with a gradation varying from 0 to 255 in a time period in which one frame period is divided into four quarters, The display is controlled to be displayed at a gray level of 0 in the time interval,
(ii) the M region is controlled to be displayed in a gradation varying from 0 to 255 in all four quadrant frame time periods,
(iii) the H region is controlled to be displayed in a gradation varying between 0 and 255 in the first quadrant frame time period and a gradation of 255 in the remaining quadrant frame time period.
3. The method of claim 2,
Wherein the subframe data applied to the display panel in the quadrant frame time period allocated to drive the respective regions of L, M, and H is controlled to increase or decrease as the gradation of the input signal increases. Display method.
A liquid crystal display device for time-divisionally displaying an input image frame in a plurality of subframes so that an image can be displayed at a frequency higher than a frame frequency of an input video signal,
A display panel divided into a plurality of regions and independently driven; And
A controller for controlling the pixels of the first area of the plurality of areas of the display panel to be driven only in a first sub frame time period and the pixels of the second area to be driven only in a second sub frame time period in which the first area is not driven, , Wherein the controller
An area classifier for classifying the input image frame into an L area having a gradation lower than a first gradation, an M area having a higher gradation than the first gradation, lower than a second gradation, and an H area higher than the second gradation based on a gradation of the input image frame; And
And a drive controller for controlling the L, M, and H regions to be driven with different sub-frame signals and different gradations.
5. The apparatus of claim 4, wherein the controller
(i) the L-th frame is divided into a first quadrant frame time period-quadrant frame time period with a gradation varying from 0 to 255 in a time period in which one frame period is divided into four quarters, The display is controlled to be displayed at a gray level of 0 in the time interval,
(ii) the M region is controlled to be displayed in a gradation varying from 0 to 255 in all four quadrant frame time periods,
(iii) the H region is displayed in the first quadrant frame time interval with a gradation varying between 0 and 255, and the remaining quadrant frame time period is displayed with 255 gradation.
6. The method of claim 5,
Wherein the subframe data applied to the display panel in the quadrant frame time interval allocated for driving each of the L, M, and H regions is controlled to increase or decrease as the gradation of the input signal increases. Display device.

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