KR100627311B1 - Liquid crystal display - Google Patents

Abstract

The present invention provides a liquid crystal display device having a backlight of a direct light source.

The liquid crystal display according to the present invention includes a liquid crystal panel and a light emitting panel serving as a backlight of the liquid crystal panel. The liquid crystal panel includes a plurality of first pixels including a plurality of first scan lines to which the first scan signal is sequentially applied, a plurality of data lines to which the data voltage is applied, and a plurality of first pixels including liquid crystal cells operated based on the first scan signal and the data voltage. It is provided. The light emitting panel includes a plurality of second scan lines to which the second scan signal is sequentially applied, a plurality of light emitting signal lines to which the light emitting voltage is applied, and a plurality of second light emitting elements to operate based on the second scan signal and the light emitting voltage. A pixel is provided. The light emitting device included in the second pixel of the light emitting panel extends in the second scanning line direction to form a linear backlight.

Liquid Crystal Display, Backlight, Organic EL

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY}

1 is an equivalent circuit diagram of each pixel in a conventional LCD.

2 is a diagram schematically illustrating a configuration of a liquid crystal display (LCD) according to a first embodiment of the present invention.

3 is a diagram illustrating the structure of the organic EL panel 600 and the equivalent circuit of the pixel in FIG. 2.

4 is a diagram illustrating a signal applied to the liquid crystal panel 100 and the organic EL panel 600 and a light emitting state of the organic EL panel 600.

5 is a diagram schematically illustrating a configuration of a liquid crystal display (LCD) according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating the structure of the organic EL panel 650 and the equivalent circuit of the pixel in FIG. 5.

7 is a timing diagram illustrating signals applied to the liquid crystal panel 100 and the organic EL panel 650.

8 is a diagram schematically illustrating a configuration of a liquid crystal display according to a third embodiment.

FIG. 9 illustrates the structure of the organic EL panel 700 and the equivalent circuit of the pixel in FIG. 8.

10 illustrates a signal applied to the liquid crystal panel 100 and the organic EL panel 700 and a light emitting state of the organic EL panel 700.

FIG. 11 illustrates a structure of an organic EL panel 750 of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having an individual light source for each pixel.

Recently, display devices are also required to be lighter and thinner in accordance with the light weight and thickness of personal computers and televisions, and according to such requirements, a liquid crystal display ("LCD") is used instead of a cathode ray tube (CRT). Flat panel displays are being developed.

An LCD applies an electric field to a liquid crystal material having an anisotropic dielectric constant injected between two substrates, and adjusts the intensity of the electric field to control the amount of light transmitted to the substrate from an external light source (backlight). Get a burn.

Such LCDs are typical of portable flat panel displays, and among them, TFT-LCDs using thin film transistors (hereinafter referred to as TFTs) as switching elements are mainly used.

In the TFT-LCD, each pixel can be modeled as a liquid crystal capacitor because electrodes (pixel electrodes and common electrodes) are disposed to face each other with a liquid crystal interposed therebetween. In such LCDs, each pixel is represented by an equivalent circuit as shown in FIG. Can be.

As shown in FIG. 1, each pixel of the liquid crystal display device includes a TFT 10 having a source electrode connected to a data line Dm, a gate electrode connected to a scan line Sn, and a drain electrode of the TFT 10. And a liquid crystal capacitor Cl connected between the common electrode Vcom and a storage capacitor Cst connected to the drain electrode of the TFT 10.

The TFT 10 provides the pixel electrode (not shown) with the data voltage Vd supplied from the data line Dm in response to the scan signal from the scan line Sn. The electric field corresponding to the difference between the data voltage provided to the pixel electrode (ie, the pixel voltage Vp and the common voltage Vcom applied to the common electrode (not shown) is equivalent to that of the liquid crystal capacitor (FIG. 1). The liquid crystal adjusts the transmittance of light in response to the intensity of the applied electric field, and the storage capacitor Cst converts the pixel voltage provided to the liquid crystal capacitor Cl to the next data voltage Vd. The light is transmitted for a predetermined time by maintaining it until it is supplied.

In general, the LCD can be divided into two methods, a color filter method and a field sequential driving method, according to a method of displaying a color image.

The color filter LCD forms a color filter layer consisting of three primary colors of red (R), green (G) and blue (B) on the upper substrate of the panel, and adjusts the amount of light transmitted through the color filter layer. The desired image is displayed. However, the color filter LCD requires unit pixels corresponding to each of the red (R), green (G), and blue (B) regions, and thus requires three times as many pixels as those for displaying black and white. Therefore, in order to obtain high resolution images, sophisticated manufacturing technology of LCD panels is required. In addition, in the color filter type LCD, red (R), green (G), and blue (B) color filters must be formed on the upper substrate, which is cumbersome in manufacturing, and the light transmittance of the color filter itself must be improved. There is a problem.

In the field-sequential driving LCD, the independent light sources of the red (R), green (G), and blue (B) colors are periodically turned on sequentially, and the pixel voltage Vp is supplied to each pixel at each lighting cycle, thereby providing a color image. Is displayed. That is, the field-sequential driving LCD does not divide one pixel into unit pixels of red (R), green (G), and blue (B), and red (R), green (G), and blue (B), respectively. The light of the three primary colors supplied from the backlight of the light source is divided into R, G, and B fields in one pixel, and time-divisionally irradiates to sequentially display colors. The colors displayed sequentially are recognized as color images by the afterimage effect of the human eye.

On the other hand, the field sequential drive type LCD uses one R light source, a G light source, and a B light source, respectively, as backlights. Therefore, the uniformity of the entire screen is not only lowered, but also the display quality is lowered due to a mismatch between the on / off time of the backlight and the application time of the data signal.

SUMMARY OF THE INVENTION The present invention has been made in an effort to solve the problems of the prior art, and to provide a liquid crystal display having a backlight of a direct light source.

A liquid crystal display device according to a feature of the present invention for achieving the above object is

A plurality of first pixels including a plurality of first scan lines to which a first scan signal is sequentially applied, a plurality of data lines to which a data voltage is applied, and a liquid crystal cell operating based on the first scan signal and the data voltage A liquid crystal panel provided; And

A plurality of second pixels including a plurality of second scan lines to which the second scan signal is sequentially applied, a plurality of light emission signal lines to which the light emission voltage is applied, and a light emitting element operating based on the second scan signal and the light emission voltage. Is provided, comprising a light emitting panel which serves as a backlight of the liquid crystal panel,

The light emitting device of the second pixel extends in the second scanning line direction to form a linear backlight.

The plurality of light emitting signal lines may include light emitting signal lines transmitting first, second, and third light emitting voltages, and a second pixel including light emitting devices emitting light of a first color may be provided on the light emitting signal lines transmitting the first light emitting voltage. Is connected to the light emitting signal line transmitting the second light emitting voltage, and a second pixel including a light emitting device emitting light of a second color is connected, and the light emitting signal line transmitting the third light emitting voltage emits light of a third color. Second pixels including light emitting devices may be connected.

The first, second, and third light emitting voltages may be voltages of a constant level at which the first, second, and third light emitting devices may emit light at predetermined luminance, respectively.

The second scan signal may be the same signal as the first scan signal.

The second pixel may include a first transistor configured to transfer the light emission voltage in response to the second scan signal; A capacitor for storing a voltage corresponding to the light emission voltage delivered by the first transistor; And a second transistor configured to output a current corresponding to the light emitting voltage to the light emitting device.

According to another aspect of the present invention, a liquid crystal display device is time-divisionally divided into a first field in which an image of a first color is displayed, a second field in which an image of a second color is displayed, and a third field in which an image of a third color is displayed. A liquid crystal display that is sequentially driven,

A liquid crystal having a plurality of first pixels including a plurality of first scan lines to which a first scan signal is applied, a plurality of data lines to which a data voltage is applied, and a liquid crystal cell operating based on the first scan signal and the data voltage. panel;

A data driver for generating the data voltage and applying the data voltage to a corresponding data line;

A scan driver for generating the first scan signal and sequentially applying the first scan signal to a corresponding first scan line;

A plurality of second scan lines to which the first scan signal generated by the scan driver is sequentially applied, a plurality of light emission signal lines to which light emission voltage is applied, and a first color and a second color based on the second scan signal and the light emission voltage A light emitting panel in which a plurality of second pixels including light emitting devices emitting light of any one of third colors is arranged in a matrix form; And

A light emitting driver for generating the light emitting voltage and applying the light emitting signal to a corresponding light emitting signal line;

The light emitting device of the first color emits light in the first field, the light emitting device of the second color emits light in the second field, and the light emitting device of the third color emits light in the third field.

The plurality of pixels connected to one light emitting signal line may include light emitting devices emitting light of the same color.

The light emitting driver applies a voltage of a first level to a light emitting signal line to which a pixel including a light emitting device of a first color is connected during a first field, and a pixel including a light emitting device of a second color is applied during a second field. A second level of voltage may be applied to the connected light emitting signal lines, and a third level of voltage may be applied to light emitting signal lines to which pixels including light emitting elements of a third color are connected during the third field.

The first, second, and third levels may be different values at which the first, second, and third light emitting devices emit light at predetermined luminance, respectively.

According to another aspect of the present invention, a liquid crystal display device includes: a liquid crystal panel including a scan line sequentially transmitting a selection signal, a data line transferring a data signal, and a liquid crystal cell connected to the scan line and the data line; And a light emitting panel disposed to correspond to the liquid crystal panel and operating as a backlight of the liquid crystal panel and including a plurality of pixels.

The pixel of the light emitting panel may include a transistor configured to output a current to a drain by applying a predetermined voltage to a gate and a source, respectively; First, second and third switching devices which are turned on in response to the first, second and third light emitting signals to transfer the currents, respectively; And first, second, and third light emitting devices that emit light corresponding to currents transmitted from the first, second, and third switching devices, respectively, in the specific directions of the first, second, and third light emitting devices. It extends and emits light in the form of a line.

The first, second, and third light emitting devices may extend in a direction parallel to the scan line of the liquid crystal panel.

The first, second and third light emitting devices may emit light of different colors.

According to another aspect of the present invention, a liquid crystal display (LCD) includes a scan line sequentially transmitting a selection signal, a data line transferring a data signal, and a liquid crystal cell connected to the scan line and the data line, wherein the image of the first color is displayed. A liquid crystal panel in which a first field to be displayed, a second field to display an image of a second color, and a third field to display an image of a third color are time-divided and sequentially driven; And a light emitting panel disposed to correspond to the liquid crystal panel and operating as a backlight of the liquid crystal panel and including a plurality of pixels.

The pixel of the light emitting panel may include a transistor configured to apply a predetermined voltage to a gate and a source, respectively, and output a current corresponding to a voltage difference between the gate and the source as a drain; First switching elements sequentially turned on during the first field to transfer the currents, respectively; A second switching element which is sequentially turned on during the second field to transfer the currents respectively; Third switching elements sequentially turned on during the third field to transfer the currents, respectively; And first, second, and third light emitting devices that emit light in first, second, and third colors, respectively, in response to currents transmitted from the first, second, and third switching devices.

Each of the first, second and third light emitting devices may extend in a specific direction to emit light in a linear form, and the first, second and third light emitting devices may extend in parallel with each other. Alternatively, the pixels of the light emitting panel may be arranged in a matrix form.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

2 is a diagram schematically illustrating a configuration of a liquid crystal display (LCD) according to a first embodiment of the present invention.

2, the LCD according to the first embodiment of the present invention includes a liquid crystal panel 100, a scan driver 200, a data driver 300, a gray voltage generator 400, a timing controller 500, and an organic light emitting diode. An EL panel 600 and a light emitting driver 610 are provided.

The liquid crystal panel 100 includes a plurality of pixels 120 arranged in a matrix at the intersection of the scan lines S1 to Sn and the data lines D1 to Dm.

The timing controller 500 receives the grayscale data signals R, G, and B data, the horizontal synchronization signal Hsync, and the vertical synchronization signal Vsync from an external or graphic controller (not shown), and the scan driver 200. A scan control signal Sg for controlling the control signal, a data control signal Sd for controlling the data driver 300, and a control signal Sb for controlling the light emitting driver 610 are generated and output. The timing controller 500 supplies the gray scale data signals R, G, and B data to the gray voltage generator 400.

The scan driver 200 generates a scan signal based on the scan control signal Sg supplied from the timing controller 500 and sequentially supplies the scan signal to the scan lines S1 to Sn to form a horizontal line to which the data voltage Vd is supplied. Choose.

The gray voltage generator 400 generates a gray voltage (data voltage Vd) corresponding to the gray data signals R, G, and B DATA, and supplies the generated data voltage Vd to the data driver 300. do. The data driver 300 supplies the data voltages Vd to the data lines D1 to Dm while being controlled by the data control signal Sd.

The organic EL panel 600 is a backlight and is connected to scan lines S1 to Sn, R, G, and B emission signal lines L_R, L_G, L_B, scan lines S1 to Sn, and R, G, and B data lines, respectively. R, G, and B pixels are included. In addition, the R, G, and B pixels each include one organic light emitting diode (hereinafter referred to as an OLED) extending substantially in the row direction of the panel. The scan lines S1 to Sn of the organic EL panel 600 are denoted by the same reference numerals as in the liquid crystal panel 100 because the scan signals output from the scan driver 200 are applied.

The light emitting driver 610 applies a voltage of a predetermined level so that each pixel of the organic EL panel 600 emits R, G, and B light based on the control signal Sb.

3 is a diagram illustrating the structure of the organic EL panel 600 and the equivalent circuit of the pixel in FIG. 2.

In FIG. 3, pixels 620_R, 620_G, and 620_B are provided in regions where the scan lines S1 to Sn and the emission signal lines L_R, L_G, and L_B cross each other. Each pixel 620_R, 620_G, and 620_B includes a switching transistor M2, a driving transistor M1, and a capacitor C, and emits OLEDs OLED_R, green ( OLED (OLED_G) which emits light in G) or OLED (OLED_B) which emits in blue (B). Specifically, the pixel 620_R connected to the scan line S1 and the light emission signal line L_R includes the OLED OLEDR1, and the pixel 620_G where the scan line S1 and the light emission signal line L_G cross each other is the OLED (OLED_G1). The pixel 620_B where the scan line S1 and the light emission signal line L_B cross each other includes an OLED OLED_B1. The case where the switching transistor M2 is an N-type transistor and the driving transistor M1 is a P-type transistor will be described as an example.

Typically, in the pixel 620_R in the region where the scan line S1 and the light emission signal line L_R cross each other, the driving transistor M1 has a source connected to the power supply voltage VDD, and a capacitor C between the gate and the source. Is connected. The cathode of the OLED OLED_R1 is connected to the reference voltage Vss and emits light corresponding to the current applied through the driving transistor M1. Here, the power supply VSS connected to the cathode of the OLED OLED_R1 is a voltage having a lower level than the power supply VDD, and a ground voltage or the like may be used.

The capacitor C maintains the gate-source voltage V _GS of the transistor M1 for a period of time. When the switching transistor M2 is turned on in response to the high level selection signal from the current scan line S1, the voltage V _L transmitted to the light emission signal line L_R is applied to the gate of the transistor M1. Then, the current I _OLED flows through the transistor M1 in response to the voltage V _GS charged between the gate and the source of the transistor M1 by the capacitor C, and the OLED corresponds to the current I _OLED . (OLED_R1) emits light. At this time, the current I _OLED flowing through the OLED OLED_R1 is represented by Equation 1 below.

Here, V _TH represents a threshold voltage of the transistor M1, and β represents a constant value. As shown in Equation 1, a current corresponding to the voltage V _L is supplied to the OLED OLED_R1, and the OLED OLED_R1 emits light at a luminance corresponding to the supplied current. In this case, the voltage V _L applied through the light emission signal line L_R may have a constant value which may emit light with a predetermined luminance as a backlight of the liquid crystal panel 100.

Next, the driving of the liquid crystal display according to the first exemplary embodiment of the present invention will be described in detail with reference to FIG. 4.

4 is a diagram illustrating a signal applied to the liquid crystal panel 100 and the organic EL panel 600 and a light emitting state of the organic EL panel 600.

In the liquid crystal display according to the first exemplary embodiment of the present invention, one frame is applied with a red (R) data signal to the liquid crystal panel 100 so that a red image is displayed, and the first field (1F) and green (G) data signals are displayed. Is applied to the liquid crystal panel 100 to display the green image, and the second field 2F and the blue (B) data signal are applied to the liquid crystal panel 100 to time-divided into the third field 3F to display the blue image. It is driven by dividing by.

Specifically, as shown in FIG. 4, during the first field 1F, a scanning signal that becomes a high level is sequentially applied to the scanning lines S1 to Sn of the liquid crystal panel 100. Each time a scan signal is applied to each scan line, a red data voltage is applied to each data line D1 to Dm to accumulate a voltage corresponding to the data voltage applied to the capacitor Cst of the pixel 120. It is arranged according to the electric field corresponding to the data voltage.

On the other hand, during the first field 1F, the high level scan signal is sequentially applied to the scan lines S1 to Sn of the organic EL panel 600. Since only the OLEDs OLED_R1 to OLED_Rn should emit light during the first field 1F, a predetermined level of emission voltage V _L is applied to the emission signal line L_R, and the OLED is applied to the other emission signal lines L_G and L_B. In order not to emit light, a voltage V _H having a level higher than the difference between the threshold voltage V _TH of the power supply VDD and the transistor M1 is applied. For example, when a high level scan signal is applied to the scan line S1 and a light emission voltage V _L of a predetermined level is applied to the light emission signal line L_R, the transistor M2 of the pixel 620_R is turned on and the applied light emission voltage is applied. The voltage corresponding to V _L is stored in the capacitor C, and the transistor M1 applies a current corresponding to the voltage difference between the source and the gate to the OLED OLED_R1 so that the OLED OLED1 emits light. Here, the voltage V _L at a predetermined level applied to the light emission signal line L_R is a voltage at which the OLED OLED_R1 may emit light at a predetermined brightness, and may be set differently according to the characteristics of the liquid crystal panel or the amount of ambient light. Next, when the scan signals are sequentially applied to the scan lines S2 to Sn, the red OLEDs OLED_R2 to OLED_Rn emit light. In this manner, as shown in FIG. 4, the red light emitted from the organic EL panel 600 is irradiated to the liquid crystal panel 100 so that a red image is displayed on the liquid crystal panel 100.

During the second field 2F, scan signals are sequentially applied to the scan lines S1 to Sn of the liquid crystal panel 100. Each time a scan signal is applied to each scan line, a green (G) data voltage is applied to each of the data lines D1 to Dm, and a voltage corresponding to the data voltage applied to the capacitor C of the pixel 120 is accumulated. The liquid crystals are arranged in accordance with the electric field corresponding to the data voltages. During the second field 2F, the scanning signals are sequentially applied to the scanning lines S1 to Sn of the organic EL panel 600. Since only the OLEDs OLED_G1 to OLED_Gn should emit light during the second field 2F, a predetermined level of emission voltage V _L is applied to the emission signal line L_G, and the OLED emits light to the other emission signal lines L_R and L_B. The voltage V _H at a level higher than the difference between the threshold voltage V _TH of the power supply VDD and the transistor M1 is applied. For example, when a scan signal is applied to the scan line S1 and a light emission voltage V _L having a predetermined level is applied to the light emission signal line L_G, the transistor M2 of the pixel 620_G is turned on and the applied light emission voltage V _L is applied. Is stored in the capacitor C, and the transistor M1 applies a current corresponding to the voltage difference between the source and the gate to the OLED OLED_G1 so that the OLED OLED_G1 emits light. Next, when the scanning signals are sequentially applied to the scanning lines S2 to Sn, the OLEDs (OLED_G2 to OLED_Gn) emit light. In this manner, as shown in FIG. 4, the green light emitted from the organic EL panel 600 is irradiated onto the liquid crystal panel 100 so that the green image is displayed on the liquid crystal panel 100.

During the third field 3F, a blue (B) data voltage is applied to the data lines D1 to Dm of the liquid crystal panel 100. The scanning signals are sequentially applied to the scanning lines S1 to Sn of the organic EL panel 600. Since only the OLEDs OLED_B1 to OLED_Bn should emit light during the second field 2F, the emission voltage V _L is applied to the emission signal line L_B. For example, when the scan signal is applied to the scan line S1 and the emission voltage V _L is applied to the emission signal line L_B, the transistor M2 of the pixel 620_B is turned on and corresponds to the applied emission voltage V _L. The voltage is stored in the capacitor C, and the transistor M1 applies a current corresponding to the voltage difference between the source and the gate to the OLED OLED_B1 so that the OLED OLED1 emits light. In this manner, when the scan signals are sequentially applied to the scan lines S2 to Sn as shown in FIG. 4, the OLEDs OLED_B2 to OLED_Bn emit light. In this way, blue light emitted blue from the organic EL panel 600 is irradiated to the liquid crystal panel 100 so that a blue image is displayed on the liquid crystal panel 100.

As described above, the liquid crystal display according to the first exemplary embodiment of the present invention uses an organic EL panel including line-shaped OLEDs formed long in the row direction. As in 4, the light is sequentially emitted. As a result, light is irradiated when the light transmittance of the liquid crystal cells in each row reaches a constant state, thereby ensuring uniformity of the display screen.

Next, a liquid crystal display according to a second exemplary embodiment of the present invention will be described with reference to FIGS. 5 to 7. The liquid crystal display device according to the second embodiment of the present invention differs from the first embodiment in that it includes an organic EL panel 650 driven by the light emission scanning driver 660.

5 is a diagram schematically illustrating a configuration of a liquid crystal display (LCD) according to a second embodiment of the present invention.

Referring to FIG. 5, the LCD according to the second embodiment of the present invention includes a liquid crystal panel 100, a scan driver 200, a data driver 300, a gray voltage generator 400, a timing controller 500, and an organic light emitting diode. An EL panel 650 and a light emission scanning driver 660 are provided. Since the liquid crystal panel 100, the scan driver 200, the data driver 300, the gray voltage generator 400, and the timing controller 500 are the same as in the first embodiment, detailed description thereof will be omitted.

The organic EL panel 650 is a backlight of the liquid crystal display, and is connected to the scan lines RS1 to RSn, GS1 to GSn, BS1 to BSn, and to the scan lines RS1 to RSn, GS1 to GSn, and BS1 to BSn, respectively. And a B pixel 670. The pixels 670 also include R, G, and B OLEDs each extending substantially in the row direction of the panel.

The light emission scan driver 660 applies a scan signal to each of the scan lines RS1 to RSn, GS1 to GSn, and BS1 to BSn of the organic EL panel 650 based on the control signal Sb. Specifically, first, scan signals are sequentially applied to the scan lines RS1 to RSn, and then scan signals are sequentially applied to the scan lines GS1 to GSn, and then sequentially scanned to the scan lines BS1 to BSn. Apply a signal.

FIG. 6 is a diagram illustrating the structure of the organic EL panel 650 and the equivalent circuit of the pixel in FIG. 5.

As shown in Fig. 6, pixels 670 are provided which are connected to the emission scan lines RS1 to RSn, GS1 to GSn, and BS1 to BSn, respectively. The pixel 670 includes a driving transistor M1 and three switching transistors M2 and includes an OLED (OLED_R) emitting light in red (R) extending in a row direction, and an OLED emitting in green (G) ( OLED_G) or OLED (OLED_B) which emits light in blue (B). All transistors included in the pixel 670 are illustrated as P-type transistors. In the pixel 670, the switching transistor M2 and the OLED (OLED_R) having a gate connected to the emission scan lines RS1 to RSn are referred to as a subpixel 670_R, and the switching transistor M2 having a gate connected to the emission scan lines GS1 to GSn. ) And OLED (OLED_G) are referred to as subpixels 670_G, and switching transistors M2 and OLED (OLED_B) having gates connected to the light emitting scan lines BS1 to BSn are referred to as subpixels 670_B.

In the subpixel 670_R, the driving transistor M1 is applied with a voltage VDD to the source, and the gate is a predetermined level lower than the difference voltage between the voltage VDD and the threshold voltage of the driving transistor M1. A light emission voltage V _E having a constant value capable of emitting light at a luminance is applied. Therefore, the driving transistor M1 outputs a current corresponding to the voltage difference between the source and the gate. The switching transistor M2 is turned on in response to the low level of the emission scan signal RS1 to transfer the current output from the driving transistor M1 to the OLED OLED_R1. The anode of the OLED OLED_R1 is connected to the drain of the switching transistor M2 and the cathode is connected to the reference voltage Vss and emits light corresponding to the current applied through the driving transistor M1.

Similarly, in the subpixel 670_G, the switching transistor M2 is turned on in response to the low level of the emission scan signal GS1 to transfer the current output from the driving transistor M1 to the OLED OLED_G1. In the subpixel 670_B, the switching transistor M2 is turned on in response to the low level of the light emission scan signal BS1 to transfer the current output from the driving transistor M1 to the OLED OLED_B1.

Next, the driving of the liquid crystal display according to the second exemplary embodiment of the present invention will be described in detail with reference to FIG. 7.

7 is a timing diagram illustrating signals applied to the liquid crystal panel 100 and the organic EL panel 650.

In the liquid crystal display according to the second exemplary embodiment of the present invention, one frame is applied with a red (R) data signal to the liquid crystal panel 100 so that a red image is displayed and the first field (1F) and green (G) data signals are displayed. Is applied to the liquid crystal panel 100 to display the green image, and the second field 2F and the blue (B) data signal are applied to the liquid crystal panel 100 to time-divided into the third field 3F to display the blue image. It is driven by dividing by.

In FIG. 7, the scan signals are sequentially applied to the scan lines S1 to Sn of the liquid crystal panel 100 during the first field 1F. Each time a scan signal is applied to each scan line, a red data voltage is applied to each data line D1 to Dm to accumulate a voltage corresponding to the data voltage applied to the capacitor Cst of the pixel 120. It is arranged according to the electric field corresponding to the data voltage. In addition, since the organic EL panel 650 should emit only the OLEDs OLED_R1 to OLED_Rn during the first field 1F, the emission scan signals RS1 to RSn are sequentially applied. For example, when the emission scan signal RS1 is applied to the organic EL panel 650, the transistor M2 of the subpixel 670_R is turned on. Then, the current output from the driving transistor M1 corresponding to the voltage difference between the source VDD and the gate V _E is applied to the OLED OLED_R1 and the OLED OLED_R1 emits light. Likewise, when the emission scan signals RS2 to RSn are sequentially applied, current is sequentially applied to the red OLEDs OLED_R2 to OLED_Rn to emit light. In this manner, red light is emitted from the organic EL panel 650 in the same manner as in the light emitting state in FIG. 4, and the emitted red light is irradiated onto the liquid crystal panel 100 to display a red image on the liquid crystal panel 100.

During the next second field 2F, scan signals are sequentially applied to the scan lines S1 to Sn of the liquid crystal panel 100. Each time a scan signal is applied to each scan line, a green data voltage is applied to each of the data lines D1 to Dm, and a voltage corresponding to the data voltage applied to the capacitor Cst of the pixel 120 is accumulated. It is arranged according to the electric field corresponding to the data voltage. Further, since the organic EL panel 650 should emit only the OLEDs OLED_G1 to OLED_Gn during the second field 2F, the emission scan signals GS1 to GSn are sequentially applied. For example, when the emission scan signal GS1 is applied to the organic EL panel 650, the transistor M2 of the subpixel 670_G is turned on. Then, a current output from the driving transistor M1 corresponding to the voltage difference between the source VDD and the gate V _E is applied to the OLED OLED_G1, and the OLED OLED_G1 emits light. Likewise, when the emission scan signals GS2 to GSn are sequentially applied, current is sequentially applied to the red OLEDs OLED_G2 to OLED_Gn to emit light. In this manner, the green light is sequentially emitted from the organic EL panel 650 in the same manner as in the light emitting state in FIG. 4, and the emitted green light is irradiated onto the liquid crystal panel 100 to display a green image on the liquid crystal panel 100. .

During the next third field 3F, scan signals are sequentially applied to the scan lines S1 to Sn of the liquid crystal panel 100. Each time a scan signal is applied to each scan line, a blue data voltage is applied to each data line D1 to Dm to accumulate a voltage corresponding to the data voltage applied to the capacitor Cst of the pixel 120. It is arranged according to the electric field corresponding to the data voltage. Further, since the organic EL panel 650 should emit only the OLEDs OLED_B1 to OLED_Bn during the third field 3F, the emission scan signals BS1 to BSn are sequentially applied. For example, when the emission scan signal BS1 is applied to the organic EL panel 650, the transistor M2 of the subpixel 670_B is turned on. Then, the current output from the driving transistor M1 corresponding to the voltage difference between the source VDD and the gate V _E is applied to the OLED OLED_B1 and the OLED OLED1 emits light. Likewise, when the emission scan signals BS2 to BSn are sequentially applied, current is sequentially applied to the red OLEDs OLED_B2 to OLED_Bn to emit light. In this manner, blue light is sequentially emitted from the organic EL panel 650 in the same manner as in the light emitting state in FIG. 4, and the emitted blue light is irradiated onto the liquid crystal panel 100 to display a blue image on the liquid crystal panel 100.

Next, a liquid crystal display according to a third exemplary embodiment of the present invention will be described with reference to FIGS. 8 to 10. The liquid crystal display according to the third embodiment of the present invention differs from the first embodiment in that the organic EL panel 700 has m OLEDs driven by one scanning line.

8 is a diagram schematically illustrating a configuration of a liquid crystal display according to a third embodiment.

In detail, the liquid crystal display according to the third exemplary embodiment includes the liquid crystal panel 100, the scan driver 200, the data driver 300, the gray voltage generator 400, the timing controller 500, and the organic EL panel 700. ) And a light emitting driver 710. Since the liquid crystal panel 100, the scan driver 200, the data driver 300, the gray voltage generator 400, and the timing controller 500 are the same as in the first embodiment, detailed description thereof will be omitted.

The organic EL panel 700 is connected to a plurality of scanning lines S1 to Sn, a plurality of light emitting signal lines L1 to Lm, a plurality of scanning lines S1 to Sn, and a plurality of light emitting signal lines L1 to Lm, respectively, arranged in a matrix. The pixel 720 is included.

The light emitting driver 710 applies a predetermined level of voltage to each of the light emitting signal lines L1 to Lm so that each pixel 720 of the organic EL panel 700 emits R, G, and B light based on the control signal Sb. Is authorized.

FIG. 9 illustrates the structure of the organic EL panel 700 and the equivalent circuit of the pixel in FIG. 8.

As shown in FIG. 9, in the organic EL panel 700, pixels 720 are provided in regions where the scan lines S1 to Sn and the emission signal lines L1 to Lm cross each other. Each pixel 720 includes a switching transistor M2, a driving transistor M1, and a capacitor C. In addition, each pixel 720 includes an OLED (OLED_R) that emits red (R), an OLED (OLED_G) that emits green (G), or an OLED (OLED_B) that emits blue (B). That is, the pixel where the scan line S1 and the light emission signal lines L1, L4, ... Lm-2 intersect includes the OLED (OLED_R), and the scan line S1 and the light emission signal lines L2, L5, ... Lm-1 The intersecting pixel includes the OLED (OLED_G), and the pixel in which the scan line S1 and the emission signal lines L3, L6, ... Dm intersect includes the OLED (OLED_B). Thus, the organic EL panel 700 includes R, G, and B OLEDs arranged in a matrix form.

Next, the driving of the liquid crystal display according to the third exemplary embodiment of the present invention will be described in detail with reference to FIG. 10.

10 illustrates a signal applied to the liquid crystal panel 100 and the organic EL panel 700 and a light emitting state of the organic EL panel 700. The liquid crystal display according to the third exemplary embodiment of the present invention also has a first field 1F in which one frame displays a red image and a second field in which a green image is displayed, similarly to the liquid crystal display according to the first embodiment. 2F) and the third field 3F in which the blue image is displayed are divided in time division and driven.

During the first field 1F, scanning signals are sequentially applied to the scanning lines S1 to Sn of the organic EL panel 700 as well. Since only the OLED OLED_R should emit light during the first field 1F, a predetermined level of emission voltage V _L is applied to the emission signal lines L1, L4, L7 ... Lm-2, and the OLED is applied to other emission signal lines. A voltage at which no light is emitted is applied. For example, when a scan signal is applied to the scan line S1 and a light emission voltage V _L having a predetermined level is applied to the light emission signal line L1, the transistor M2 of the pixel 720 is turned on and corresponds to the applied voltage. Stored in the capacitor C, the transistor M1 applies a current corresponding to the voltage difference between the source and the gate to the OLED OLED_R so that the OLED OLED_R emits light. Similarly, as shown in the light emitting state of FIG. 10, the OLEDs OLED_R connected to the light emitting signal lines L1, L4, L7..., Lm-2 emit light sequentially. In this way, the red light emitted from the organic EL panel 700 passes through the liquid crystal panel 100 to display a red image.

Then, during the second field, the scan signal is sequentially applied to the scan lines S1 to Sn of the organic EL panel 200, and the light emission voltage is applied to the light emission signal lines L2, L5, L8 ... Lm-1. Accordingly, as shown in the light emission state of FIG. 10, the OLEDs OLED_G connected to the light emission signal lines L2, L5, L8..., Lm-1 emit light sequentially. In this way, the green light emitted from the organic EL panel 700 passes through the liquid crystal panel 100 to display a green image.

Finally, during the third field, the scan signal is sequentially applied to the scan lines S1 to Sn of the organic EL panel 200, and the light emission voltage is applied to the light emission signal lines L3, L6, L9 ... Lm. Accordingly, as shown in the light emission state of FIG. 10, the OLED OLED_B connected to the light emission signal lines L3, L6, L9..., Lm sequentially emits light. In this way, blue light emitted from the organic EL panel 700 passes through the liquid crystal panel 100 to display a blue image.

As described above, the liquid crystal display according to the third exemplary embodiment of the present invention can further secure uniformity of the screen by using a dot-type backlight using an organic EL panel including OLEDs arranged in a matrix.

Next, a liquid crystal display according to a fourth exemplary embodiment of the present invention will be described with reference to FIG. 11. The liquid crystal display according to the fourth embodiment differs from the second embodiment in that it includes an organic EL panel 750 arranged in an R, G, and B OLED matrix. Since the liquid crystal display according to the fourth embodiment is the same as the second embodiment except for the organic EL panel 750, a detailed description thereof will be omitted and the organic EL panel 750 will be described in detail below.

FIG. 11 illustrates a structure of an organic EL panel 750 of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

In Fig. 11, pixels 770 connected to light emission scan lines RS1 to RSn, GS1 to GSn, and BS1 to BSn are provided. The element 770 includes a driving transistor M1 and a switching transistor M2, respectively, and includes an OLED (R) emitting red light, an OLED (G) emitting green light, or an OLED (B) emitting blue light. Sub-pixels 770_R, 770_G, and 770_B.

As shown in FIG. 7, light emission scan signals RS1 to RSn having a low level are sequentially applied to the organic EL panel 750 in the first field 1F, and have a low level sequentially in the second field 2F. The light emission scan signals GS1 to GSn are applied to the organic EL panel 750, and the light emission scan signals BS1 to BSn having a low level are sequentially applied to the organic EL panel 750 in the third field 3F. Therefore, OLED (R) emits light sequentially in the first field, OLED (G) emits light sequentially in the second field, and OLED (B) emits light sequentially in the third field.

Accordingly, as shown in the light emitting state of FIG. 10, since the organic EL panel 750 emits light in a dot form, the liquid crystal display is driven by a backlight in dot form, thereby further securing uniformity of the screen.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights. For example, in the above-described embodiment of the present invention, the LCD of the field sequential driving method has been described as an example, but may be applied to various LCDs other than the field sequential driving LCD. In addition, although the example in which the organic EL panel using the organic light emitting diode is applied as the backlight has been described, various light emitting panels including the light emitting device may be applied as the backlight.

As described above, according to the present invention, the uniformity of the entire screen can be improved by using an active matrix active matrix light emitting display panel as a backlight, and the liquid crystal is applied to an electric field corresponding to the applied data voltage. Accordingly, the quality of the display image can be further improved because the backlight panel emits light for a period such as while maintaining the arranged state.

In addition, by applying the same scan signal to the liquid crystal panel and the backlight panel, it is possible to solve the problem of inconsistency between the backlight on / off time and the data signal application time.

Claims (16)

A plurality of first pixels including a plurality of first scan lines to which a first scan signal is sequentially applied, a plurality of data lines to which a data voltage is applied, and a liquid crystal cell operating based on the first scan signal and the data voltage A liquid crystal panel provided; And A plurality of second pixels including a plurality of second scan lines to which the second scan signal is sequentially applied, a plurality of light emission signal lines to which the light emission voltage is applied, and a light emitting element operating based on the second scan signal and the light emission voltage. Is provided, comprising a light emitting panel which serves as a backlight of the liquid crystal panel, The second pixel is A first transistor transferring the emission voltage in response to the second scan signal; A capacitor for storing a voltage corresponding to the light emission voltage delivered by the first transistor; And A second transistor configured to output a current corresponding to the light emitting voltage to the light emitting device; The light emitting device of the second pixel extends in the second scanning line direction to form a linear backlight. The method of claim 1, The plurality of light emitting signal lines may include light emitting signal lines transmitting first, second and third light emitting voltages. A second pixel including a light emitting device emitting light of a first color is connected to the light emitting signal line transmitting the first light emitting voltage, and a light emitting device emitting light of a second color is included on the light emitting signal line transmitting the second light emitting voltage. And a second pixel including a light emitting device emitting light of a third color, to a light emitting signal line transmitting the third light emitting voltage. The method of claim 2, And the first, second, and third light emitting voltages are voltages of a constant level at which the first, second, and third light emitting elements can emit light at a predetermined brightness, respectively. The method of claim 1, And the second scan signal is the same signal as the first scan signal. delete A liquid crystal display device in which a first field in which an image of a first color is displayed, a second field in which an image of a second color is displayed, and a third field in which an image of a third color are displayed are time-divided and sequentially driven. A liquid crystal having a plurality of first pixels including a plurality of first scan lines to which a first scan signal is applied, a plurality of data lines to which a data voltage is applied, and a liquid crystal cell operating based on the first scan signal and the data voltage. panel; A data driver for generating the data voltage and applying the data voltage to a corresponding data line; A scan driver for generating the first scan signal and sequentially applying the first scan signal to a corresponding first scan line; A plurality of second scan lines to which the second scan signal generated by the scan driver is sequentially applied, a plurality of light emission signal lines to which light emission voltage is applied, and a first color and a second color based on the second scan signal and the light emission voltage A light emitting panel in which a plurality of second pixels including light emitting devices emitting light of any one of third colors is arranged in a matrix form; And A light emitting driver configured to generate the light emitting voltage and apply the light emitting signal to a corresponding light emitting signal line; The second pixel is A first transistor transferring the emission voltage in response to the second scan signal; A capacitor for storing a voltage corresponding to the light emission voltage delivered by the first transistor; And A second transistor configured to output a current corresponding to the light emitting voltage to the light emitting device; The light emitting device of the first color emits light in the first field, the light emitting device of the second color emits light in the second field, and the light emitting device of the third color emits light in the third field. The method of claim 6, A plurality of pixels connected to one light emitting signal line includes a light emitting device that emits light of the same color. The method of claim 7, wherein The light emitting drive unit, During the first field, a voltage of a first level is applied to a light emitting signal line to which pixels including light emitting elements of a first color are connected, and to the light emitting signal line to which pixels including light emitting elements of a second color are connected during a second field. 2. A liquid crystal display device applying a voltage of two levels and applying a voltage of a third level to a light emitting signal line to which pixels including light emitting elements of a third color are connected during a third field. The method of claim 8, And the first, second, and third levels are different values at which the first, second, and third light emitting elements can emit light at predetermined luminance, respectively. A liquid crystal panel including a scan line sequentially transmitting a selection signal, a data line transferring a data signal, and a liquid crystal cell connected to the scan line and the data line; And A light emitting panel disposed corresponding to the liquid crystal panel and operating as a backlight of the liquid crystal panel, the light emitting panel including a plurality of pixels; The pixel of the light emitting panel, A transistor configured to output a current to a drain by applying a predetermined voltage to the gate and the source, respectively; First, second and third switching devices which are turned on in response to the first, second and third light emitting signals to transfer the currents, respectively; And First, second and third light emitting device for emitting light corresponding to the current transmitted from the first, second and third switching device, The liquid crystal display device which extends in a specific direction of the first, second and third light emitting elements to emit light in the form of a line. The method of claim 10, And the first, second and third light emitting elements extend in a direction parallel to the scan line of the liquid crystal panel. The method of claim 10, The first, second and third light emitting devices emit light of different colors. A first field in which an image of a first color is displayed, and an image of a second color is displayed, including a scan line sequentially transmitting a selection signal, a data line transferring a data signal, and a liquid crystal cell connected to the scan line and the data line. A liquid crystal panel in which a second field to be displayed and a third field in which an image of a third color is displayed are time-divided and sequentially driven; And A light emitting panel disposed corresponding to the liquid crystal panel and operating as a backlight of the liquid crystal panel, the light emitting panel including a plurality of pixels; The pixel of the light emitting panel, A transistor configured to apply a predetermined voltage to a gate and a source, respectively, and output a current corresponding to a voltage difference between the gate and the source as a drain; First switching elements sequentially turned on during the first field to transfer the currents, respectively; A second switching element which is sequentially turned on during the second field to transfer the currents respectively; Third switching elements sequentially turned on during the third field to transfer the currents, respectively; And first, second, and third light emitting devices that emit light in first, second, and third colors, respectively, in response to currents transmitted from the first, second, and third switching devices. The liquid crystal display device which extends in a specific direction of the first, second and third light emitting elements to emit light in the form of a line. delete The method of claim 13, The first, second and third light emitting devices extend in parallel with each other. delete

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