KR20130046477A - Stereoscopic image display device and method for driving thereof - Google Patents

Abstract

PURPOSE: A 3D image display device and an operating method thereof are provided to prevent a user from seeing an abnormal image when watching a 2D image with polarizing glasses. CONSTITUTION: When the same voltage is supplied to an operating electrode(31) and a reference electrode(33), an active retarder(30) emits first polarized light. When different voltages are supplied to the operating electrode and the reference electrode, the active retarder emits second polarized light. A left eye filter of polarizing glasses passes only the first polarized light. A right eye filter of the glasses passes the second polarized light. First and second switches are turned off in a 3D mode. The first and the second switches are turned on in a 2D mode.

Description

Stereoscopic Display and Driving Method {STEREOSCOPIC IMAGE DISPLAY DEVICE AND METHOD FOR DRIVING THEREOF}

The present invention relates to a stereoscopic image display device including a liquid crystal display panel and a driving method thereof.

The stereoscopic image display device displays a stereoscopic image using a binocular parallax technique or an autostereoscopic technique. The binocular parallax method uses parallax images of right and left eyes with large stereoscopic effect, and can be divided into a spectacular method and a non-spectacular method. The spectacle method includes a pattern retarder method in which a polarization direction of a left and right parallax image is displayed on a direct-view display device or a projector and a stereoscopic image is realized using polarized glasses. In addition, the glasses method is a shutter glass method for time-division displaying left and right parallax images on a direct-view display device or a projector, and realizing a stereoscopic image using liquid crystal shutter glasses. In addition, the spectacle method includes an active retarder method for time division of left and right parallax images on a direct-view display device or a projector and simultaneously changing polarization directions, and realizing a stereoscopic image using polarized glasses. In the autostereoscopic method, an optical plate such as a parallax barrier and a lenticular lens is generally used to realize a stereoscopic image by separating an optical axis of a parallax image.

1 and 2 illustrate driving of a conventional stereoscopic image display device.

The active retarder type stereoscopic image display device uses liquid crystals in the same manner as a general liquid crystal panel, and the movement of the liquid crystal has a characteristic of varying transmittance under the influence of an electric field caused by an operating voltage. As shown in FIG. 1, in the 3D mode, an on / off voltage for operating a liquid crystal to the active retarder is applied in synchronization with the left / right eye frame frequency of the display panel, thereby polarizing the active retarder. The direction changes periodically and is incident separately from the left and right eyes of the polarizing glasses.

Referring to FIG. 2, since the operating voltage is not applied to the active retarder in the 2D mode, the floating state is maintained. In this case, the charge current remaining inside the liquid crystal cell by the driving voltage applied during the 3D mode operation is maintained. ((charge current) causes the liquid crystal to remain unstable. If the user is wearing polarized glasses, the image through the polarized glasses will display an abnormal image in which the left and right images are mixed.) In 2D mode, you can see abnormal images through polarized glasses and need to prevent them.

The present invention provides a stereoscopic image display device and a driving method thereof capable of preventing abnormal images from being viewed through polarized glasses when switching from 3D mode to 2D mode.

In order to achieve the above object, a stereoscopic image display device according to an embodiment of the present invention is a display panel for displaying a 2D image in the 2D mode, and time-divisionally display the left and right images in the 3D mode, the display panel A backlight unit including light sources for irradiating light and attached to the display panel to rotate the liquid crystal by a voltage difference between the driving electrodes and the reference electrode, whereby the same voltage is applied to the driving electrode and the reference electrode; An active retarder that emits light of one polarization and emits light of a second polarization when the driving electrode and the reference electrode are applied with different voltages; and a left eye filter that passes only the light of the first polarization; Polarizing glasses including a right eye filter for passing only the light of the polarized light; The drive electrode is connected to the ground through the first switch, The reference electrode is connected to ground through a second switch, wherein the first switch and the second switch are turned off in the 3D mode, and the first switch and the second switch are turned on in the 2D mode. .

In the 3D mode, a 3D mode signal is applied to the first switch and the second switch so that the first switch and the second switch are turned off.

In the 2D mode, a 2D mode signal is applied to the first switch and the second switch so that the first switch and the second switch are turned on so that the driving electrode and the reference electrode are grounded.

The display panel displays the left eye image during the odd frame period in the 3D mode and the right eye image during the even frame period.

In addition, the driving method of the stereoscopic image display device according to an embodiment of the present invention is a display panel for displaying a 2D image in the 2D mode, time-divisional display of the left eye image and the right eye image in the 3D mode, and the light on the display panel A backlight unit including light sources for irradiating light, and a liquid crystal rotated by a voltage difference between driving electrodes and a reference electrode attached to the display panel so that the same voltage is applied to the driving electrode and the reference electrode. An active retarder that emits light of polarized light and emits light of a second polarized light when different voltages are applied to the driving electrode and the reference electrode, a left eye filter through which only the light of the first polarized light passes, Polarizing glasses including a right eye filter for passing only light of two polarizations, wherein the driving electrode is connected to ground through a first switch, and the reference The pole is connected to the ground through a second switch, the first switch and the second switch is turned off in the 3D mode, the first switch and the second switch is turned on in the 2D mode, The method may further include applying a 3D mode signal to the first switch and the second switch in the 3D mode to turn off the first switch and the second switch, and time-divisionally display a left eye image and a right eye image on the display panel. And turning on the first switch and the second switch by applying a 2D mode signal to the first switch and the second switch in the 2D mode, and displaying a 2D image on the display panel. do.

The stereoscopic image display device and the driving method thereof according to the present invention have an advantage of preventing abnormal images in which left and right images are mixed when a user views a 2D image while wearing polarized glasses. Accordingly, the stereoscopic image display device of the present invention has an advantage of improving the display quality of the image and giving a smooth viewing feeling to the user.

1 and 2 are views showing the driving of the conventional stereoscopic image display device.
3 is a block diagram illustrating a stereoscopic image display device according to an embodiment of the present invention.
4 is a view showing a grounding structure of an active retarder according to an embodiment of the present invention.
5 and 6 illustrate driving of a stereoscopic image display device according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, when it is determined that a detailed description of known functions or configurations related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. The names of components used in the following description are selected in consideration of ease of specification, and may be different from actual product names.

3 is a block diagram illustrating a stereoscopic image display device according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a ground structure of an active retarder according to an embodiment of the present invention.

Referring to FIG. 3, a stereoscopic image display device according to an embodiment of the present invention may include a display panel 10, polarizing glasses 20, an active retarder 30, a gate driver 110, a data driver 120, The active retarder driver 130, the timing controller 140, the host system 150, and the like are included.

The display panel 10 includes a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting diode (OLED), OLED) and the like can be implemented as a display panel. Although the display panel 10 is illustrated as being a liquid crystal display device in the following embodiment, it should be noted that the display panel 10 is not limited to the liquid crystal display device.

In the display panel 10, a liquid crystal layer is formed between two substrates, an upper substrate and a lower substrate. The substrate of the display panel 10 may be formed of glass, plastic, or film. A color filter array including a black matrix, a color filter, a common electrode, and the like is formed on the upper substrate of the display panel 10. The data line D and the gate lines G (or scan lines) cross each other on the lower substrate of the display panel 10, and are formed by the data lines D and the gate lines G. A TFT array in which pixels are arranged in a matrix form in defined cell regions is formed.

Each pixel of the display panel 10 is connected to a thin film transistor and is driven by an electric field between the pixel electrode and the common electrode. The common electrode is formed on the upper substrate in a vertical electric field driving method such as twisted nematic (TN) mode and vertical alignment (VA) mode, and a horizontal electric field driving such as IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode. The pixel electrode is formed on the lower substrate. The liquid crystal mode of the display panel 10 may be implemented in any of the liquid crystal modes as well as the above-described TN mode, VA mode, IPS mode, and FFS mode.

The display panel 10 displays an image under the control of the timing controller 140. The display panel 10 displays a 2D image in 2D mode, and time-divisionally displays a left eye image and a right eye image in 3D mode. The operation of the display panel 10 in the 2D mode and the 3D mode according to an exemplary embodiment of the present invention will be described later with reference to FIGS. 5 and 6.

As the display panel 10, a transmissive liquid crystal display panel that modulates light from the backlight unit may be selected. The backlight unit includes a light source, a light guide plate (or a diffusion plate), a plurality of optical sheets, and the like, which light up according to a driving current supplied from the backlight driver. The backlight unit may be implemented as a direct type backlight unit or an edge type backlight unit. The light sources of the backlight unit may include one of a hot cathode fluorescent lamp (HCFL), a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a light emitting diode (LED), or two or more light sources. .

The backlight driver generates a driving current for turning on light sources of the backlight unit. The backlight driver turns on / off a driving current supplied to the light sources under the control of the backlight controller. The backlight controller SPI generates backlight control data in which backlight brightness and lighting timing are adjusted according to the global / local dimming signal DIM input from the host system 150 and the backlight control signal C _BL input from the timing controller 140. (Serial Pheripheral Interface) Output to the backlight driver in data format.

An upper polarizer is attached to the upper substrate of the display panel 10, and a lower polarizer is attached to the lower substrate. The light transmission axis of the upper polarizer and the light transmission axis of the lower polarizer are perpendicular to each other. In addition, an alignment film for setting a pre-tilt angle of the liquid crystal is formed on the upper substrate and the lower substrate. A spacer is formed between the upper substrate and the lower substrate of the display panel 10 to maintain a cell gap of the liquid crystal layer. The active retarder 30 is positioned on the display panel 10.

The active retarder 30 may include a reference electrode and a plurality of driving electrodes that face each other with the liquid crystal layer interposed therebetween, and may be implemented as a liquid crystal panel without a polarizer, a color filter, and a black matrix. The active retarder 30 may be implemented in twisted nematic (TN) mode. When the first driving voltage is applied to the driving electrodes, the active retarder 30 passes the light without changing the polarization characteristic of the light incident from the display panel 10. The active retarder 30 delays a phase value of light incident from the display panel 10 by λ / 2 (λ is a wavelength of light) when the second driving voltage is applied to the driving electrodes. Accordingly, the active retarder 30 emits light of the first polarization when the first driving voltage is applied to the driving electrodes, and emits light of the second polarization when the second driving voltage is applied to the scan electrodes. .

The polarizing glasses 20 include a left eye filter L _F that transmits only the polarization of the left eye image L, and a right eye filter R _F that transmits only the polarization of the right eye image R. Therefore, the left eye filter L _F of the polarizing glasses 20 transmits only the first polarization of the left eye image L and blocks the second polarization of the right eye image R. The right eye filter R _F of the polarizing glasses 20 transmits only the second polarization of the right eye image R and blocks the first polarization of the left eye image L.

Light passing through the upper polarizer of the display panel 10 has polarization characteristics of first polarization. When the first driving voltage is applied to the driving electrodes, the active retarder 30 passes the light of the first polarized light incident from the display panel 10 as it is. In addition, when the second driving voltage is applied to the driving electrodes, the active retarder 30 delays the light of the first polarized light incident from the display panel 10 by λ / 2 to convert the second polarized light. Therefore, the user sees only the image of the first polarization incident to the left eye filter L _F of the polarizing glasses 20 to the left eye, and the second polarization incident to the right eye filter R _F of the polarizing glasses 20 to the right eye. You will only see the video. As a result, the user may feel a three-dimensional effect due to binocular parallax.

The active retarder driver 130 supplies a reference voltage and a first or second driving voltage to the active retarder 30 under the control of the timing controller 140. The active retarder driver 130 may determine whether the active retarder driver 130 is a 2D mode or a 3D mode according to the mode signal MODE input from the timing controller 140. The active retarder driver 130 supplies a reference voltage to the reference electrode of the active retarder 30 in the 3D mode. The active retarder driver 130 may drive the first or second driving voltages to the driving electrodes of the active retarder 30 according to the active retarder control signal C _AR input from the timing controller 140 in the 3D mode. To supply.

The data driver 120 includes a plurality of source drive ICs. The source drive ICs convert the image data RGB input from the timing controller 140 into positive / negative gamma compensation voltages to generate positive / negative analog data voltages. The positive / negative analog data voltages output from the source drive ICs are supplied to the data lines D of the display panel 10.

The gate driver 110 sequentially supplies gate pulses synchronized with the data voltage to the gate lines G of the display panel 10 under the control of the timing controller 140. The gate driver 110 may be composed of a plurality of gate drive integrated circuits each including a shift register, a level shifter for converting an output signal of the shift register into a swing width suitable for TFT driving of the liquid crystal cell, have. Alternatively, the gate driver 110 may be directly formed on the lower substrate 10b of the display panel 10 by using a gate drive IC in panel (GIP) method. In the GIP method, the level shifter may be mounted on a printed circuit board (PCB), and the shift register may be formed on the lower substrate 10b of the display panel 10.

The timing controller 140 may control the gate driver 110 based on the image data RGB output from the host system 150, the timing signals Vsync, Hsync, DE, and CLK, and the mode signal MODE. ) And a data driver control signal to the data driver 120. In particular, the timing controller 140 multiplies the frame frequency by L times L (L is a natural number of 2 or more) times, preferably 4 times or more of the input frame frequency, and controls the gate driver control signal and the data driver based on the multiplied frame frequency. A signal, a backlight control signal, and an active retarder control signal. The input frame frequency is 50 Hz in PAL (Phase Alternate Line) scheme and 60 Hz in NTSC (National Television Standards Committee) scheme.

The gate driver control signal includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable signal (Gate Output Enable, GOE), and the like. The gate start pulse (GSP) controls the timing of the first gate pulse. The gate shift clock GSC is a clock signal for shifting the gate start pulse GSP. The gate output enable signal GOE controls the output timing of the gate driver 110.

The data driver control signal includes a source start pulse (SSP), a source sampling clock (SSC), a source output enable signal (SOE), a polarity control signal (POL), and the like. . The source start pulse SSP controls the data sampling start time of the data driver 120. The source sampling clock is a clock signal that controls the sampling operation of the data driver 120 based on the rising or falling edge. If the digital video data to be input to the data driver 120 is transmitted using a mini LVDS (Low Voltage Differential Signaling) interface standard, the source start pulse SSP and the source sampling clock SSC may be omitted. The polarity control signal POL inverts the polarity of the data voltage output from the data driver 120 every L (L is a natural number) horizontal period period. The source output enable signal SOE controls the output timing of the data driver 120.

The host system 150 supplies the image data RGB to the timing controller 140 through an interface such as a low voltage differential signaling (LVDS) interface and a transition minimized differential signaling (TMDS) interface. In addition, the host system 150 supplies timing signals Vsync, Hsync, DE, and CLK, a 2D / 3D mode signal MODE, and the like to the timing controller 140.

Meanwhile, referring to FIG. 4, the active retarder 30 of the present invention includes a liquid crystal cell 35 between the driving electrode 31 and the reference electrode 33. The driving electrode 31 is connected to the ground through the first switch 1SW, and the reference electrode 33 is connected to the ground through the second switch 2SW. In the 3D mode, a 3D mode signal from the host system is applied to the first switch 1SW connected to the reference electrode 33 and the second switch 2SW connected to the driving electrode 31, so that the first switch ( 1SW and the second switch 2SW are turned off. On the other hand, in the 2D mode, a 2D mode signal is applied from the host system to the first switch 1SW and the second switch 2SW, so that the first switch 1SW and the second switch 1SW are turned on ( On). Accordingly, the driving electrode 31 and the reference electrode 33 are connected to the ground.

That is, in order to remove the charge current in the liquid crystal cell 35 of the active retarder 30, the driving voltage applied to the driving electrode 31 and the reference voltage applied to the reference electrode 33 are changed when switching from the 3D mode to the 2D mode. The current accumulated in the liquid crystal cell 35 of the active retarder 30 may be removed by a method of grounding the ground (GND) voltage and the ground. In the present invention, only the polarization in one direction is generated at the same reference voltage and the driving voltage, so that the normal image can be viewed only through the right eye lens or the left eye lens of the polarizing glasses, and the other lens is in a non-transmissive state so that the black image is seen.

In the present invention, the 3D / 2D mode signal is directly applied to the first switch 1SW and the second switch 1SW from the host system. However, the present invention is not limited thereto, and the 3D / 2D mode is not limited to the timing controller or the active retarder driver. A signal may be applied. The 3D / 2D mode signal may be a 3D enable signal, the 3D mode signal may be an enable high signal, and the 2D mode signal may be an enable low signal.

5 and 6 illustrate driving of a stereoscopic image display device according to an exemplary embodiment.

2 and 5, when the 3D mode is input by the user, the 3D mode signal is input from the host system to the first switch and the second switch respectively connected to the driving electrode and the reference electrode of the active retarder. The first switch and the second switch to which the 3D mode signal is applied are turned off. The display panel 10 time-divisionally displays the left eye image and the right eye image according to the 3D mode signal. For example, the left eye image data is displayed on all the pixels of the display panel 10 during the odd frame period, and the right eye image data is displayed on all the pixels of the display panel 10 during the even frame period. The active retarder 140 transmits the first polarized light of the left eye image in response to the Voff voltage during the odd frame period, and transmits the second polarized light of the right eye image in response to the Von voltage during the even frame period. The user may view the left eye image displayed on the display panel 10 during the odd frame period through the polarizing glasses 20, and the right eye image R1 displayed on the display panel 10 during the even frame period. You will enjoy the stereoscopic image.

Meanwhile, referring to FIG. 6, when the 2D mode is input by the user, the 2D mode signal is input from the host system to the first switch and the second switch respectively connected to the driving electrode and the reference electrode of the active retarder. The first switch and the second switch to which the 2D mode signal is applied are turned on to connect the driving electrode and the reference electrode to the ground. The display panel 10 displays an image that is not time-divided according to the 2D mode signal. Since the driving electrode and the reference electrode are grounded, the active retarder 140 transmits only one polarized light because the driving electrode and the reference electrode are equipotential. For example, if the active retarder 140 transmits the first polarized light of the left eye image when the active retarder 140 is equipotential, the user may display the display panel during the odd and even frame periods through the left eye filter L _F of the polarizing glasses 20. The left eye image shown in (10) can be seen. In addition, since the active retarder 140 transmits only the first polarized light of the left eye image, the right eye filter R _F of the polarizing glasses 20 sees the black image for every frame period.

Therefore, when the user changes to the 2D mode while viewing the 3D image, different polarized light is transmitted through the polarized glasses to the left eye and the right eye, thereby preventing the user from viewing the abnormal image. Therefore, the stereoscopic image display apparatus according to an embodiment of the present invention has an advantage of improving the display quality of the image and giving a smooth viewing feeling to the user.

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 invention. Therefore, the present invention should not be limited to the details described in the detailed description, but should be defined by the claims.

10 display panel 20 polarized glasses
30: active retarder 110: gate driver
120: data driver 130: active retarder driver
140: timing controller 1SW. 2SW: first switch, second switch
150: host system

Claims (5)

A display panel for displaying a 2D image in 2D mode and time-dividing the left eye image and the right eye image in 3D mode;
A backlight unit including light sources for irradiating light to the display panel;
Attached to the display panel to rotate the liquid crystal by a voltage difference between the driving electrodes and the reference electrode, thereby emitting light having a first polarization when the same voltage is applied to the driving electrode and the reference electrode, An active retarder which emits light of a second polarization when different voltages are applied to the reference electrode; And
And a left eye filter for passing only the light of the first polarization and a right eye filter for passing only the light of the second polarization.
The driving electrode is connected to the ground through a first switch, the reference electrode is connected to the ground through a second switch, the first switch and the second switch are turned off in the 3D mode, and in the 2D mode. And a first switch and the second switch are turned on.
The method according to claim 1,
In the 3D mode, a 3D mode signal is applied to the first switch and the second switch so that the first switch and the second switch are turned off.
The method according to claim 1,
In the 2D mode, a 2D mode signal is applied to the first switch and the second switch so that the first switch and the second switch are turned on so that the driving electrode and the reference electrode are grounded. Device.
The method according to claim 1,
And the display panel displays the left eye image during the odd frame period in the 3D mode and the right eye image during the even frame period.
A display panel for displaying a 2D image in 2D mode and time-dividing a left eye image and a right eye image in 3D mode, a backlight unit including light sources for irradiating light to the display panel, and attached to the display panel By rotating the liquid crystal by the voltage difference between the driving electrodes and the reference electrode, when the same voltage is applied to the driving electrode and the reference electrode, the first polarized light is emitted, and the driving electrode and the reference electrode are different voltages. A polarizing glasses including an active retarder that emits light of a second polarization when applied, a left eye filter that passes only light of the first polarization, and a right eye filter that passes only light of the second polarization, The driving electrode is connected to ground through a first switch, and the reference electrode is connected to ground through a second switch. The first switch and the second switch is turned off, the 2D mode when the first switch and the three-dimensional display device that the second switch is turned on,
Applying a 3D mode signal to the first switch and the second switch in the 3D mode to turn off the first switch and the second switch, and time-divisionally display a left eye image and a right eye image on the display panel; And
And turning on the first switch and the second switch by applying a 2D mode signal to the first switch and the second switch in the 2D mode, and displaying a 2D image on the display panel. Method of driving a stereoscopic image display device.

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