KR20120003758A - Scanning backlight driving method and stereoscopic image display device using the same - Google Patents

Abstract

PURPOSE: A scanning backlight driving method and a stereoscopic image display device using the same are provided to improve 3D crosstalk and motion blur by turning on the light sources of a backlight unit according to response time of a liquid crystal. CONSTITUTION: A backlight unit for radiating light to a display panel is divided into a plurality of blocks. The gradation distribution of a stereoscopic image is analyzed by dividing a stereoscopic image according to each block. A block representative is extracted based on a gradation distribution analysis result(S103). A difference between the block representative of a prior image and the block representative of another current image is calculated(S104). A backlight lighting timing is controlled according to the calculated difference(S105). A control signal for lighting blocks is generated at a backlight lighting timing controlled according to each block(S106).

Description

SCANNING BACKLIGHT DRIVING METHOD AND STEREOSCOPIC IMAGE DISPLAY DEVICE USING THE SAME}

The present invention relates to a scanning backlight driving method and a stereoscopic image display apparatus using the same.

The stereoscopic image display apparatus is divided into a binocular parallax technique and an autostereoscopic technique. The binocular parallax method uses a parallax image of the left and right eyes with a large stereoscopic effect, and there are glasses and no glasses, both of which are put to practical use. In the spectacle method, the polarization of the left and right parallax images is displayed on the direct view display device or the projector or displayed in a time division method. The glasses method implements a stereoscopic image using polarized glasses or liquid crystal shutter 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.

The shutter glasses type stereoscopic image display apparatus displays a left eye image and a right eye image on a display panel by time division. The glasses worn by the user include a left eye shutter that transmits light of the left eye image and a right eye shutter that transmits light of the right eye image. Therefore, the user sees only the left eye image during the odd frame, and only the right eye image during the excellent frame period, so that the user can feel a three-dimensional effect with binocular parallax.

The stereoscopic image display device may be implemented using a liquid crystal display device. The LCD displays an image by controlling an electric field applied to the liquid crystal layer to modulate the light incident from the backlight unit. In a liquid crystal display device implementing a stereoscopic image, the liquid crystal of the display panel has a slow response time due to intrinsic viscosity, elasticity, and the like, as shown in Equations 1 and 2.

(gamma)는 액정분자의 회전점도(rotational viscosity)를 각각 의미한다. In Equation 1, τ _r is the rising time when a voltage is applied to the liquid crystal, V _a is the applied voltage, and V _F is the Freederick Transition Voltage at which the liquid crystal molecules start the tilt motion. ), D is the cell gap of the liquid crystal cell,

(gamma) means rotational viscosity of liquid crystal molecules, respectively.

In Equation 2, τ _f denotes a falling time during which the liquid crystal is restored to its original position by the elastic restoring force after the voltage applied to the liquid crystal is turned off, and K denotes an elastic modulus inherent to the liquid crystal.

Background Art A scanning backlight driving technique is known as a method for solving a problem due to the response speed of liquid crystal in a liquid crystal display. The scanning backlight driving technique sequentially flashes the light sources of the backlight unit along the scanning direction of the display line, thereby providing an effect similar to that of impulsive driving of the cathode ray tube (CRT).

In the case of a 3D image liquid crystal display device which alternately displays left and right eye images while driving at high speed in time division, the scanning backlight has a left eye image in consideration of response delay time of the liquid crystal to improve the motion picture response time (MPRT). It is driven in accordance with a section that changes from the right eye image, or from the right eye image to the left eye image. However, in this case, the previous frame data and the next frame data, the left eye and right eye images, or the right eye and left eye images may be mixed. Accordingly, motion blur, which is a screen drag phenomenon, and 3D crosstalk in which a left eye image and a right eye image overlap each other may occur.

Disclosure of Invention An object of the present invention is to provide a scanning backlight driving method capable of improving motion blur and 3D crosstalk and a stereoscopic image display apparatus using the same.

In order to achieve the above object, the scanning backlight driving method of the present invention comprises the steps of: dividing the backlight unit for irradiating light to the display panel into a plurality of blocks; Dividing an input image for each block and analyzing a gray distribution of the input image for each block; Extracting a representative value for each block based on a result of analyzing the gradation distribution, and calculating a difference between the representative value for each block of a previous monocular image and a representative value for each block of another current monocular image; Adjusting a backlight lighting timing according to the calculated difference between the representative value of each block of the previous monocular image and the representative value of each block of the current monocular image; And generating a control signal for lighting the blocks at the backlight lighting timing adjusted for each block.

The stereoscopic image display device of the present invention is irradiated with light to the display panel, the backlight unit divided into a plurality of blocks; A gradation analyzer for dividing an input image by blocks and analyzing a gradation distribution of the input image for each block; A representative value calculator configured to extract a representative value for each block based on a result of analyzing the gray scale distribution, and calculate a difference between a representative value for each block of a previous monocular image and a representative value for each block of another current monocular image; A scanning controller adjusting a backlight lighting timing according to the calculated difference between the representative value of each block of the previous monocular image and the representative value of each block of the current monocular image; And a backlight controller configured to generate a control signal for lighting the blocks at the backlight lighting timing adjusted for each block.

The present invention analyzes the gradation distribution of pixel data for each scanning block, adjusts the backlight lighting timing according to the analyzed gradation distribution, and lights up the light sources according to the adjusted backlight lighting timing. As a result, the present invention can improve motion blueer and 3D crosstalk by lighting the light sources of the backlight unit in accordance with the response time of the liquid crystal.

1 is a perspective view illustrating a display panel and a backlight unit when driving a scanning backlight.
2 is a waveform diagram illustrating driving of a conventional scanning backlight in a stereoscopic image display device.
3 is a flowchart illustrating a scanning backlight driving method of a stereoscopic image display device according to an exemplary embodiment of the present invention.
4 is a waveform diagram illustrating driving of a scanning backlight of a stereoscopic image display device according to an exemplary embodiment of the present invention.
5A to 5C are gradation distribution diagrams showing examples of various histogram analysis results.
6 is a block diagram illustrating a stereoscopic image display device according to an exemplary embodiment of the present invention.
7 is a block diagram illustrating in detail the timing controller of FIG. 6.

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 numbers refer to like elements throughout. 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.

Component names used in the following description may be selected in consideration of ease of specification, and may be different from actual product part names.

The present invention can be applied to a shutter glasses type stereoscopic image display device that time-divisions a left eye image and a right eye image and separates light incident to the left and right eyes of the user through the liquid crystal shutter glasses.

1 is a perspective view illustrating a display panel 10 and a backlight unit 20 when driving a scanning backlight. The backlight unit 20 is driven by being divided into M blocks (M is a natural number of two or more). The backlight unit 20 of FIG. 1 is driven by being divided into five blocks BL1 to BL5. The input image of the display panel 10 is divided to correspond to each of the blocks BL1 to BL5 of the backlight unit 20.

2 is a waveform diagram illustrating driving of a conventional scanning backlight in a stereoscopic image display device. Referring to FIG. 2, the data RGB _R and RGB _L of the right and left eye images are scanned from the first line to the L (L is a natural number) line of the display panel during one frame period during driving of the scanning backlight. The display panel of FIG. 2 has 1080 vertical lines.

The display panel continuously displays the same right eye image data RGB _R during the 4N + 1 (N is a natural number) and the 4N + 2 frame periods, and the same left eye image data during the 4N + 3 and 4N + 4 frame periods. (RGB _L ) is displayed continuously. In addition, the gamma characteristic of the right eye image data RGB _{R which} is continuous during the 4N + 1 and 4N + 2 frame periods is differently converted into units of one frame period, and the continuous gamma characteristic of the 4N + 3 and 4N + 4 frame periods is converted. The gamma characteristic of the left eye image data RGB _L may be differently converted in units of one frame period.

Since the 3D image display device is driven at high speed by time division, the frame frequency is multiplied by P (P is a natural number of 2 or more) times the input frame frequency. The frame frequency of FIG. 2 is quadrupled with respect to the input frame frequency. The input frame frequency is 50 Hz in PAL (Phase Alternate Line) scheme and 60 Hz in NTSC (National Television Standards Committee) scheme. One frame period is 5 msec when the frame frequency is 200 Hz, and one frame period is about 4.16 msec when the frame frequency is 240 Hz.

The blocks BL1 to BL5 of the backlight unit 20 are driven in order from the first block to the fifth block along the scanning directions of the right eye and left eye image data RGB _R and RGB _L from the top of the display panel. Also, the blocks BL1 to BL5 of the backlight unit 20 are sequentially driven after the liquid crystal response delay time of the right eye and left eye image data RGB _R and RGB _L elapses. This is because 90% or more of the target luminances of the right and left eye image data RGB _R and RGB _L of the pixel may be displayed after the liquid crystal response delay time of the display panel has elapsed. Therefore, the blocks BL1 to BL5 of the backlight unit 20 are turned on after the liquid crystal response delay time of the display panel elapses, and the blocks BL1 to BL5 of the backlight unit 20 are changed from the left eye image to the right eye image. It lights up in accordance with the section changed from the right eye image to the left eye image.

In the scanning backlight driving, each of the blocks BL1 to BL5 of the backlight unit 20 is driven by different backlight unit control signals C _BLU1 to C _BLU5 . The first to fifth backlight unit control signals C _BLU1 to C _BLU5 sequentially turn on the blocks BL1 to BL5 of the backlight unit 20 after the liquid crystal response delay time of the display panel elapses.

In addition, each of the blocks BL1 to BL5 of the backlight unit 20 is turned on at a constant pulse width modulation duty ratio every 8.33 ms. The PWM duty ratio is shown in equation (3).

In Equation 3, DR denotes a PWM duty ratio, d ₁ denotes a high logic level (back light unit lighting time) of a PWM signal, and d ₂ denotes a low logic level (back light unit lighting time) of a PWM signal. The PWM duty ratio of FIG. 2 is approximately 18%, and the backlight unit lighting time d ₁ is approximately 1.49 ms.

The liquid crystal shutter glasses open the right or left eye shutter in synchronization with a section in which the blocks BL1 to BL5 of the backlight unit 20 are turned on. When the right eye image data RGB _R is scanned on the display panel in synchronization with a section in which the blocks BL1 to BL5 of the backlight unit 20 are turned on, the right eye shutter is opened and the left eye image data RGB _L is scanned. , Open the left eye shutter.

As shown in FIG. 2, when the blocks BL1 to BL5 of the backlight unit 20 are turned on in accordance with a section from the left eye image to the right eye image or the right eye image to the left eye image, the left and right eyes, or the right and left eyes The picture may look mixed. Therefore, there is a problem that motion blue and 3D crosstalk occur.

3 is a flowchart illustrating a scanning backlight driving method of a stereoscopic image display device according to an exemplary embodiment of the present invention. 4 is a waveform diagram illustrating driving of a scanning backlight of a stereoscopic image display device according to an exemplary embodiment of the present invention. Referring to FIG. 3, the 3D image display apparatus of the present invention analyzes a histogram for each block to extract a gray level representative value, and a gray level representative value for each block of a previous monocular image and a block gray level for another current monocular image. The difference ΔG _BL of the representative value is calculated. Then, the block-by-block scanning lighting timing corresponding to the calculated ΔG _BL is selected, and the backlight unit is driven based on the backlight lighting timing. In FIG. 3, the previous monocular image is a left eye image, and another current monocular image is a right eye image. Hereinafter, the scanning driving method of the stereoscopic image display device according to the exemplary embodiment of FIG. 3 will be described in detail with reference to FIG. 4.

The stereoscopic image display device of the present invention continuously displays the same right eye image data RGB _R during the 4N + 1 (N is a natural number) and the 4N + 2 frame period, and the 4N + 3 and 4N + 4 frame periods. While the same left eye image data RGB _L is continuously displayed. The right eye image data RGB _{R of} the 4N + 1 and 4N + 2 frame periods is analyzed to scan the backlight unit for each block, and the right eye shutter ST _R of the liquid crystal shutter glasses is opened. Therefore, the first step determines whether RGB data RGB _R of the right eye image is input. (S101)

When the data RGB _R of the right eye image is input, the second step histogram analyzes data of the input image to be displayed on the display panel corresponding to each of the blocks BL1 to BL5 of the backlight unit 20. The analyzed histogram represents the gradation distribution of the input image to be displayed on the display panels of blocks BL1 to BL5 of the backlight unit 20.

5A to 5C are gradation distribution diagrams showing examples of various histogram analysis results. 5A to 5C, the X axis represents a gray value and the Y axis represents the number of data of the input image. When the right eye and left eye image data RGB _R and RGB _L are 8 bits, the gray scale value is represented by G0 to G255. The luminance distribution for each gradation is various in the form of luminance distribution in the low gradation region as shown in FIG. 5A, luminance distribution in the high gradation region as in FIG. May appear. (S102)

When the histogram analysis is completed, the third step extracts the gray level representative values G _BL1 to G _BL5 for each block. The gray level representative values G _BL1 to G _{BL5 for each} block may be calculated as a gray level value, a mode value, or an average value corresponding to the upper i% as a result of the histogram analysis. Here, i% may be specified as any value between 5% and 10%.

4, the amount of change in the gray scale representative values G _BL1 to G _BL5 for each block is shown. Looking at the gray level represented by the block of the previous left-eye image value (G _BL1 ~ G _BL5), the gradation representative value of the first block (BL 1) (G _BL1) is the gradation representative value of G0, the second block (BL 2) (G _BL2 ) is G0, and the gray scale representative value G _BL3 of the third block BL 3 is G150, and the gray scale representative value G _BL4 of the fourth block BL 4 is G70, and the gray scale of the fifth block BL 5. The representative value G _BL5 is G0. Looking at the current gradation representative value (G _BL1 ~ G _BL5) per block of the right-eye image, a first block gradation representative value of (BL 1) (G _BL1) is G50, the gradation representative value of the second block (BL 2) (G _BL2 ) is G200, and the gradation representative value G _BL3 of the third block BL 3 is G250, and the gradation representative value G _BL4 of the fourth block BL 4 is G70, and the gradation of the fifth block BL 5. The representative value G _BL5 is G127. Here, the gray level representative values G _BL1 to G _{BL5 for} each block mean gray level representative values of data of the input image corresponding to each of the blocks BL1 to BL5 of the backlight unit 20. (S103)

The fourth step calculates a difference ΔG _BL1 to ΔG _BL5 between the gray level representative value of each block of the previous left eye image and the gray level representative value of each block of the current right eye image. In FIG. 4, when the differences ΔG _BL1 to ΔG _{BL5 of the} blocks are calculated, the difference ΔG _BL1 of the gradation representative value of the first block BL 1 is determined by G50 and the second block BL 2. The difference ΔG _BL2 of the gray scale representative value is G200, and the difference ΔG _BL3 of the gray scale representative value of the third block BL 3 is G100, and the difference ΔG _BL4 of the fourth block BL 4 is The difference ΔG _BL5 of the gray level representative value of G70 and the fifth block BL 5 is G127. (S104)

Block-by-block backlight on timings T _ON1 to T _ON5 are selected in correspondence with the calculated difference ΔG _BL1 to ΔG _BL5 of each block. The calculated difference ΔG _BL1 to ΔG _BL5 for each block and backlight ON timing T _ON1 to T _{ON5 for each} block may be stored in a register or memory in a table form. . Block-by-block backlight on timings T _ON1 to T _ON5 corresponding to the calculated differences in gray level representative values for blocks ΔG _BL1 to ΔG _BL5 may be determined through a preliminary experiment.

Referring to the block-backlit timing T _ON1 to T _{ON5 of} FIG. 4 in detail, since the difference ΔG _{BL1 of} the first block BL 1 is G50, the response delay of the liquid crystal is increased in the first block BL 1. small. Therefore, the timing at which the data of the input image reaches the target luminance is predicted to be faster, and the backlight lighting timing T _ON1 of the first block BL 1 is shifted forward.

Since the difference ΔG _BL2 of the second block BL 1 is G200, the response delay of the liquid crystal is large in the second block BL 2. Therefore, the timing at which the pixel data reaches the target luminance will not be accelerated, and the backlight lighting timing T _ON2 of the second block BL 2 becomes a section that changes from the right eye image to the left eye image.

Since the difference ΔG _BL3 of the third block BL 3 is G100, the response delay of the liquid crystal is small in the third block BL 3. Therefore, the timing at which the pixel data reaches the target luminance is expected to be faster, and the backlight lighting timing T _ON3 of the third block BL 3 is also shifted forward.

Since the difference ΔG _BL4 of the fourth block BL 4 is G70, the response delay of the liquid crystal is small in the fourth block BL 4. Therefore, the timing at which the pixel data reaches the target luminance is expected to be faster, and the backlight lighting timing T _ON4 of the fourth block BL 4 is also shifted forward.

Since the difference ΔG _BL5 of the fifth block BL 5 is G127, the response delay of the liquid crystal is small in the fifth block BL 5. Therefore, the timing at which the pixel data reaches the target luminance is expected to be faster, and the backlight lighting timing T _ON5 of the fifth block BL 5 is also shifted forward.

As a result, since the response delay of the liquid crystal is short in the first block BL 1, the third block BL 3, the fourth block BL 4, and the fifth block BL 5, the image is changed from the right eye image to the left eye image. It does not need to be lit to match the interval. However, since the response delay of the liquid crystal is large, the second block BL 2 is turned on in accordance with a section changing from the right eye image to the left eye image.

Further, the difference (ΔG _BL1 ~ ΔG _BL5) is more backlight lighting timing is small (T _ON1 ~ T _ON5) of the block by the gradation representative value is further shifted forward. As the difference between the gray level representative values ΔG _BL1 to ΔG _{BL5 for} each block decreases, the response delay time of the liquid crystal decreases, so that the data of the input image of each of the blocks BL1 to BL5 of the backlight unit 20 is shorter. This is because the target luminance can be reached.

Furthermore, the blocks BL1 to BL5 of the backlight unit 20 may not be sequentially implemented. As shown in FIG. 4, when the difference ΔG _BL2 of the gray scale representative value of the second block BL 2 is large and the difference ΔG _BL3 of the gray scale representative value of the third block BL is small, the third block BL The backlight lighting timing T _ON3 of 3) is pulled forward a lot, but the backlight lighting timing T _ON2 of the second block BL 2 is a section that changes from the right eye image to the left eye image.

Meanwhile, since the lighting duration d ₁ of each of the blocks BL1 to BL5 of the backlight unit 20 is the same, each of the blocks BL1 to BL5 of the backlight unit 20 is turned on for the same time. However, since the backlight lighting timings T _ON1 to T _ON5 vary according to the difference ΔG _BL1 to ΔG _BL5 of the gray scale representative value, the unlit duration d ₂ and the PWM duty ratio of each of the blocks change.

According to the present invention, the smaller the difference between the gray level representative values (ΔG _BL1 to ΔG _BL5 ) of each block is shifted forward by the scanning lighting timing (T _ON1 to T _ON5 ) for each block, the existing right eye and left eye images are mixed. And resulting motion blur and 3D crosstalk can be minimized. (S105)

The backlight unit is driven to scan the backlight unit based on the selected block-by-block backlight on timing T _ON . In addition, the right eye shutter of the liquid crystal shutter glasses is opened in synchronization with the lighting periods of the blocks BL1 to BL5 of the backlight unit 20. (S106)

The left eye image data RGB _{L of} the 4N + 3 and 4N + 4 frame periods is analyzed to scan the backlight unit for each block, and the left eye shutter ST _L of the liquid crystal shutter glasses is opened. When the left eye image data RGB _L is input, the scanning backlight driving method of the stereoscopic image display apparatus according to the present invention is the same as when the right eye image data RGB _R is input (S101 to S106).

6 is a block diagram illustrating a stereoscopic image display device according to an exemplary embodiment of the present invention. Referring to FIG. 6, the liquid crystal display of the present invention includes a display panel 10, a backlight unit 20, a liquid crystal shutter glasses 30, a display panel driver 110, a backlight driver 120, and a liquid crystal shutter glasses control signal. A receiver 130, a liquid crystal shutter glasses control signal transmitter 140, a backlight controller 150, a timing controller 160, and a system board 170 are provided.

The display panel 10 alternately displays left eye image data RGB _L and right eye image data RGB _R under the control of the timing controller 160. The display panel 10 may display two-dimensional image data RGB without distinguishing between the left eye image and the right eye image under the control of the timing controller 160. The display panel 10 may be selected as a hold type display device requiring the backlight unit 20. As the hold type display device, a transmissive liquid crystal display panel that modulates light from the backlight unit 20 may be selected.

The transmissive liquid crystal display panel includes a thin film transistor (TFT) substrate and a color filter substrate. A liquid crystal layer is formed between the TFT substrate and the color filter substrate. On the TFT substrate, the data lines and the gate lines (or scan lines) are formed to cross each other on the lower glass substrate, and the liquid crystal cells are arranged in a matrix form in the cell regions defined by the data lines and the gate lines. do. The TFT formed at the intersection of the data lines and the gate lines transfers the data voltage supplied through the data lines to the pixel electrode of the liquid crystal cell in response to the scan pulse from the gate line. For this purpose, the gate electrode of the TFT is connected to the gate line, and the source electrode is connected to the data line. The drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell. The common voltage is supplied to the common electrode facing the pixel electrode. The color filter substrate includes a black matrix and a color filter formed on the upper glass substrate. The common electrode is formed on the upper glass substrate in a vertical electric field driving method such as twisted nematic (TN) mode and vertical alignment (VA) mode, and a horizontal electric field such as IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode. The driving method is formed on the lower glass substrate together with the pixel electrode. A polarizing plate is attached to each of the upper glass substrate and the lower glass substrate of the transmissive liquid crystal display panel, and an alignment layer for setting the pre-tilt angle of the liquid crystal is formed. A spacer for maintaining a cell gap of the liquid crystal layer is formed between the upper glass substrate and the lower glass substrate of the transmissive liquid crystal display panel. The liquid crystal mode of the transmissive liquid crystal display panel may be implemented in any liquid crystal mode as well as the above-described TN mode, VA mode, IPS mode, FFS mode.

The display panel driver 110 includes a data driver circuit and a gate driver circuit. The data driving circuit converts the data (RGB _L , RGB _R ) of the left eye image and the right eye image input from the timing controller 160 into the positive / negative gamma compensation voltage in the 3D image, thereby converting the positive / negative analog data. Generate voltages. Positive / negative analog data voltages output from the data driving circuit are supplied to the data lines of the display panel 10. The gate driving circuit sequentially supplies gate pulses (or scan pulses) synchronized with data voltages to gate lines of the display panel 10.

The backlight unit 20 is turned on for a predetermined time, irradiates light to the display panel 10, and turns off for other periods. The backlight unit 20 includes a light source, a light guide plate (or a diffusion plate), a plurality of optical sheets, and the like, which are turned on according to the driving power supplied from the backlight driver 120. The backlight unit 20 may be implemented as a direct type backlight unit or an edge type backlight unit. The light sources of the backlight unit 20 may include any 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. can do.

The backlight unit 20 may be divided into M blocks. In FIG. 6, the backlight unit 20 is divided into five blocks BL1 to BL5. In addition, the display panel 10 may also be divided into M blocks corresponding to the backlight unit 20. This is because, when the backlight unit 20 is scanning driven, the pixel data is analyzed by histogram for each block of the display panel 10 to select the backlight lighting timing T _ON .

The backlight driver 120 generates driving power for turning on light sources of the backlight unit 20. The backlight driver 120 periodically turns on / off driving power supplied to the light sources under the control of the backlight controller 150. The backlight driver 120 receives a backlight control signal C _{BLU that} controls the blocks BL1 to BL5 of the backlight unit 20, and drives driving power to each of the blocks BL1 to BL5 of the backlight unit 20. To supply.

The liquid crystal shutter glasses 30 have a left eye shutter ST _L and a right eye shutter ST _R that are electrically controlled separately. Each of the left eye shutter ST _L and the right eye shutter ST _R includes a first transparent substrate, a first transparent electrode formed on the first transparent substrate, a second transparent substrate, a second transparent electrode formed on the second transparent substrate, and And a liquid crystal layer sandwiched on the first and second transparent substrates. The reference voltage is supplied to the first transparent electrode and the ON / OFF voltage is supplied to the second transparent electrode. Each of the left eye shutter ST _L and the right eye shutter ST _R transmits light from the display panel 10 when the ON voltage is supplied to the second transparent electrode, while the OFF eye is supplied to the second transparent electrode. Light from the display panel 10 is blocked.

The liquid crystal shutter glasses control signal transmitter 140 is connected to the timing controller 160 and receives the liquid crystal shutter glasses control signal C _ST input from the timing controller 160 through the wired / wireless interface. To be sent). The liquid crystal shutter glasses control signal receiver 130 is installed in the liquid crystal shutter glasses 30 to receive the liquid crystal shutter control signal C _ST through a wired / wireless interface, and the liquid crystal shutter glasses according to the liquid crystal shutter control signal C _ST . The left eye shutter ST _L and the right eye shutter ST _R of 30 are alternately opened and closed.

When the liquid crystal shutter control signal C _ST is input to the liquid crystal shutter control signal receiver 130 as a first logic value, the ON voltage is supplied to the second transparent electrode of the left eye shutter ST _L while the right eye shutter ST is supplied. _The OFF voltage is supplied to the second transparent electrode of _R ). When the liquid crystal shutter control signal C _ST is input to the liquid crystal shutter control signal receiver 130 as the second logic value, the OFF voltage is supplied to the second transparent electrode of the left eye shutter ST _L , while the right eye shutter ST is supplied. _The ON voltage is supplied to the second transparent electrode of _R ). Therefore, the left eye shutter ST _L of the liquid crystal shutter glasses 30 is opened when the liquid crystal shutter control signal C _ST is generated as the first logic value, and the right eye shutter ST _R of the liquid crystal shutter glasses 30 is It is opened when the liquid crystal shutter control signal C _ST is generated as the second logic value. The first logic value may be set to a high logic voltage, and the second logic value may be set to a high logic voltage.

The display panel control signal C _DIS includes a data control signal for controlling the operation timing of the data driving circuit and a gate control signal for controlling the operation timing of the gate driving circuit. The data 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 driving circuit. The source sampling clock is a clock signal that controls the sampling operation of the data driving circuit based on the rising or falling edge. If the digital video data to be input to the data driving circuit is transmitted in 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 driving circuit in a period of L (L is a positive integer) horizontal period. The source output enable signal SOE controls the output timing of the data driver circuit.

The gate 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 driving circuit.

The backlight controller 150 receives information on the backlight-turn-on timing T _{ON for each} block from the timing controller 160, and controls the backlight control signal C _{BLU of} each of the blocks BL1 to BL5 of the backlight unit 20. Is output to the backlight driver 120. The backlight control signal C _BLU controls the backlight driver 120 to periodically turn on and off the blocks BL1 to BL5 of the backlight unit 20. Detailed description thereof will be described later with reference to FIG. 7.

The system board 170 converts the resolution of the image data RGB input from the outside to match the resolution of the display panel 10 and converts various timing signals (Vsync, Hsync, DE, CLK, etc.) into the timing controller 160. To transmit.

FIG. 7 is a detailed block diagram illustrating the timing controller 160 of FIG. 6. Referring to FIG. 7, the timing controller 160 of the present invention includes a gray scale analyzer 161, a representative value calculator 162, a scanning controller 163, and a register 164.

The gray scale analyzer 161 receives RGB data from the system board 170 and analyzes a gray scale distribution of data of the input image of each of the blocks BL1 to BL5 of the backlight unit 20. The gray value of each of the data of the input image may be represented by luminance information Y calculated using R data, G data, and B data as variables. The gray scale distribution of the data of the input image analyzed by the gray analyzer 161 may appear in various forms including the forms of FIGS. 5A to 5C.

The representative value calculator 162 extracts the gray representative value G _BL from the gray distribution analyzed by the gray analyzer 161. The gray level representative value G _{BL for each} block may be extracted as a gray level value, a mode value, or an average value corresponding to the upper i% of the histogram analysis result. Here, i% may be specified as any value between 5% and 10%.

The representative value calculator 162 calculates a difference ΔG _BL between the gray level representative value of each block of the previous monocular image and the gray level representative value of each block of the current monocular image from the extracted gray level representative value G _BL . Therefore, the representative value calculator 162 may include a memory to store the gray level representative value for each block of the previous monocular image. The representative value calculator 162 outputs, to the scanning controller 163, a difference ΔG _BL between the calculated gray scale representative value of each block of the previous monocular image and another gray scale representative value of each block of the current monocular image.

Also, the scanning controller 163 registers the difference ΔG _BL between the gray level representative value of each block of the previous monocular image received from the representative value calculator 162 and the gray level representative value of each block of the current monocular image. Can be printed as The register 164 stores a difference (ΔG _BL ) between the block gray level representative value of the previous monocular image and the block gray level representative value of another current monocular image in the form of a table, and the backlight lighting timing T _{ON for each} block. to be.

The register 164 receives a difference (ΔG _BL ) between the gray level representative value of each block of the previous monocular image and the gray level representative value of each block of the current monocular image, and stores the backlight lighting timing T _ON stored in the input address. ) The number of registers 164 may be equal to the number of blocks BL1 to BL5 of the backlight unit 20, and in this case, the difference ΔG _BL of the gray level representative value of the first block may be the first register. The difference ΔG _BL of the gray level representative value of the second block may be implemented in a format input to the second register. The scanning controller 163 outputs the backlight-turning timing T _ON for each block input from the register 164 to the backlight controller 150.

The backlight controller 150 receives a backlight turn-on timing T _{ON for each} block from the scanning controller 163. The backlight controller 150 may generate a pulse once per horizontal period, such as a horizontal sync signal Hsync or a data enable signal DE, and a vertical sync signal Vsync or a gate start pulse GSP. As described above, a signal in which a pulse is generated once in one frame period (one vertical period) may be input from the timing controller 160. The backlight controller 150 determines the backlight on-time timing T _ON for each block through the various timing signals, and outputs the backlight control signals C _BLU1 to C _BLU5 for each block whose timing is adjusted according to the determination result. 120). The backlight driver 120 supplies driving power to each of the blocks BL1 to BL5 of the backlight unit 20 according to the backlight control signal C _BLU received from the backlight controller 150.

The timing controller 160 controls the liquid crystal shutter glasses control signal C to open the liquid crystal shutter glasses in synchronization with the lighting intervals of the blocks BL1 to BL5 of the backlight unit 20 from the backlight lighting timing T _ON and various timing signals. _ST ) is output to the liquid crystal shutter glasses control signal transmitter 140. The liquid crystal shutter glasses control signal C _ST is transmitted to the liquid crystal shutter glasses control signal receiver 130 so that the left eye shutter ST _L and the right eye shutter ST _{R of the} liquid crystal shutter glasses 30 are synchronized with the lighting period of the blocks. Open and close.

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: backlight unit
30: liquid crystal shutter glasses 110: display panel driver
120: backlight driver 130: liquid crystal shutter glasses control signal receiver
140: liquid crystal shutter glasses control signal transmission unit 150: backlight control unit
160: timing controller 161: gradation analyzer
162: representative value calculation unit 163: scanning control unit
164: Register 170: System Board

Claims (13)

Dividing a backlight unit into a plurality of blocks for irradiating light to the display panel;
Dividing an input image for each block and analyzing a gray distribution of the input image for each block;
Extracting a representative value for each block based on a result of analyzing the gradation distribution, and calculating a difference between the representative value for each block of a previous monocular image and a representative value for each block of another current monocular image;
Adjusting a backlight lighting timing according to the calculated difference between the representative value of each block of the previous monocular image and the representative value of each block of the current monocular image; And
And generating a control signal to light the blocks at the backlight timing adjusted for each block. The method of claim 1,
Opening the right eye shutter when the display panel displays the right eye image, and opening the liquid crystal shutter glasses that open the left eye shutter in synchronization with the lighting duration of the blocks when the left eye image is displayed. Way. The method of claim 1,
The lighting duration of the blocks is,
Scanning backlight driving method characterized in that the same set for each block. The method of claim 1,
The backlight lighting timing is
And the smaller the difference between the calculated block representative value of the previous monocular image and the block representative value of another current monocular image is shifted forward. The method of claim 1,
The backlight lighting timing is adjusted to the time after the response delay time of the liquid crystal. The method of claim 1,
And illuminating the blocks according to the control signal. A backlight unit irradiating light to the display panel and divided into a plurality of blocks;
A gradation analyzer for dividing an input image by blocks and analyzing a gradation distribution of the input image for each block;
A representative value calculator configured to extract a representative value for each block based on a result of analyzing the gray scale distribution, and calculate a difference between a representative value for each block of a previous monocular image and a representative value for each block of another current monocular image;
A scanning controller adjusting a backlight lighting timing according to the calculated difference between the representative value of each block of the previous monocular image and the representative value of each block of the current monocular image; And
And a backlight controller configured to generate a control signal for lighting the blocks at the backlight on timing adjusted for each block. The method of claim 7, wherein
3. The 3D image display device of claim 1, wherein the lighting durations of the blocks are equally set for each block. The method of claim 7, wherein
The display panel further includes a liquid crystal shutter glasses for opening the right eye shutter when the right eye image is displayed and opening the left eye shutter when the left eye image is displayed.
The liquid crystal shutter glasses are opened in synchronization with the lighting duration of the blocks. The method of claim 7, wherein
And the backlight lighting timing is shifted forward as the difference between the calculated block representative value of the previous monocular image and the block representative value of the current another monocular image is smaller. The method of claim 7, wherein
The backlight lighting timing is adjusted to a time after the response delay time of the liquid crystal. The method of claim 7, wherein
And a backlight driver to turn on the blocks according to the control signal. The method of claim 7, wherein
The scanning control unit,
And a register configured to store a difference between a representative value of each block of the previous monocular image calculated for each block, a representative value of each block of the current monocular image, and a backlight lighting timing.

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