Abstract:
A configuration/apparatus to drive emphasized data to an LCD screen, including enhancing frame difference data with compensation and enhancement factors. These factors can consider a backlight phase input from a variable backlight control system.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority from a provisional patent application entitled “Adaptive Overdrive And Backlight Control For TFT LCD Pixel Accelerator” filed on Jul. 16, 2002 and bearing Ser. No. 60/396,456. 
     
    
     
       BACKGROUND  
         [0002]    1. Field of the Invention  
           [0003]    The invention is related to improvement of a liquid-crystal display (LCD) control and driving scheme. Particularly, it relates to acceleration of the pixel response and the speed of an active matrix liquid crystal display panel. It relates to improvement the performance of motion picture presentation of active matrix liquid crystal display panel.  
           [0004]    2. Related Art  
           [0005]    Active matrix liquid crystal (also called “TFT LCD” (Thin Film Transistor Liquid Crystal Display)) display panels are widely in use in PC (Personal Computer) based display applications, such as notebook PCs and PC monitors, because they provide light weight, thin thickness, and low power consumption features. Moreover, recent efforts to develop high performance TFT LCD panels are resolving limitations of conventional panel performance, such as resolution, contrast, brightness, and viewing angle. It is expected that LCD monitor unit shipping number will become larger than CRT (Cathode Ray Tube) monitor shipping in the PC monitor market in near future. Further, the demand for multimedia and thus, LCD, is expected to become stronger, since the types of image sources are expanded from only PC-based still information to motion pictures from DVD (Digital Video Disc) players, video games, digital TVs and so on.  
           [0006]    However, one drawback of LCD performance for motion video is slow response time. The response time in LCD tends to be slower in grayscale, and the worst values in TN LC (twisted nematic liquid crystal) material reaches 4 to 5 frame periods. This deteriorates display quality in moving images greatly, and results in ghosting and reduced resolution in the moving image. In order to resolve this issue, fast response LC materials have been developed. However, unfortunately these have not been sufficient in improving the slow response time in grayscale, since the origin of slow response is related to LC operation dynamics.  
           [0007]    As mentioned above, conventional active matrix liquid crystal display (TFT LCD) uses TN LC (twisted nematic liquid crystal) material. The response time of a liquid crystal display is directly related to the driving voltage changes, changes that depend on the starting tone and the targeting tone. The response time of black to white or white to black is comparatively as late as 30-50 milliseconds. Moreover, the response times to the middle tone from other tones, like the middle tone from white, the middle tone from black, and a certain middle tone from other middle tones, are very slow and as late as 50-100 milliseconds. When the screen has so many middle tone images, such as TV images, and when the display shows moving image, a residual image phenomenon where the image still lingers in the wrong position is generated.  
           [0008]    Moreover, all of the existing and conventional liquid-crystal display panel schemes use a display system of a so called “hold type,” which continues to display a picture of one frame interval during the period which is in the same one cycle of a picture signal. If moving images, such as TV images, are displayed on this hold-type liquid-crystal display, the picture, which is moving frame by frame, is displayed for one frame in the same position. In order to pursue the tracing edges viewed by the human eye, averaging happens to those moving edges of the pictures on the eye retina and hence the human eye will recognize these images as the blurring outline in a picture.  
           [0009]    As mentioned above, in displaying a moving image on a liquid-crystal display, two problems exist. To solve the first problem, when display data has changed, detected with the display data of the previous frame, the display data is then emphasized and written into the driver more than the amount of the change to the pixel data. Several emphasizing schemes (commonly called over-driving) of changing display data currently exist and are named based on different theoretical concepts, for example: LAO (level adaptive over-drive), FFD (feed-forwarding drive), and DCC (dynamic contrast compensation or dynamic charge compensation). All of these schemes use a simple algorithm with a full frame buffer. The response speed of a middle tone response becomes almost equivalent to the response speed of a white display or a black display and the residual images at the time of moving display are improved to some extent by these schemes. But, all of these schemes fall short and are not applicable in mass-production with reasonable low cost and price.  
           [0010]    Regarding the second problem, within one frame interval, there is an experimental scheme to eliminate edge blurring by driving the liquid-crystal panel by more than 2 times faster than the frame speed, turning on back-light only the second half of frame interval, and it must use the double speed response liquid crystal material. Another scheme uses the insertion of a black-screen data in the first half and similarly by driving the display data in the second half of the frame interval. This can eliminate human visual feeling of blurring edges. However, these schemes can be utilized only under some special limitations and only at the laboratory level. Further there is an existing problem of how to apply these schemes in low cost mass-production products.  
           [0011]    [0011]FIG. 1 is a block diagram of a computer system to explain the background of display sub-systems as they relate to computer systems. System  100  includes a CPU (Central Processor Unit)  105 , coupled to a System/Host Bus  140 , for accessing all system resources, to execute parameter setting for all system configuration, to perform I/O operation, to execute software program, and to update display information, and so on.  
           [0012]    System  100  also includes Memory Sub-System  110 , Peripheral Sub-System  120 , and Display Sub-System  130 , coupled to System/Host Bus  140 . Memory Sub-System  110  comprises Random Access Memory (RAM)  112  and Read Only Memory (ROM)  114 . Memory subsystem  110  typically stores miscellaneous data, some programs for execution by CPU, and intermediate results of executing programs. Peripheral Sub-System  120  includes a keyboard  128 , a printer  126 , a disk  124 , and other peripheral interfaces. The disk  124  can be used as a secondary external memory for CPU data and programs.  
           [0013]    Display Sub-System  130  includes a display controller  132 , a display memory  134 , and a display device  136 . Display device  136  is a CRT or an LCD. In some cases both devices can be included in the system as operating simultaneously. The Display Sub-System  130  performs screen refreshing for such display devices as monitors or LCD screens.  
           [0014]    [0014]FIG. 2( a ) is a detailed view of a conventional display sub-system. The CPU  105  executes parameter setting for all registers in this Display Sub-System when initializing after system power up. The Display Sub-System has several registers in it and CPU writes all initializing values to the registers that are needed to initialize. In some cases, such as when operation mode changing happens, the CPU  105  re-writes those registers that are needed to meet the new operation mode. The CPU  105  sends the update values to Parameter Registers  233  through System/Host Bus  140  in the case. Parameter Registers  233  receive all necessary parameters to specify all values for registers in each module of the Display Sub-System.  
           [0015]    Sync/Timing Generator  235  generates synchronous signals and timing signals based on those parameter values. The synchronous signals and timing signals are distributed and used to control operation inside the Display Sub-System.  
           [0016]    CPU  105  updates information to be displayed on the display device through System/Host Bus  140  (such as ISA or PCI bus) when display data are changed. The update information are transferred to and from FIFO Buffer  236  with the aid of Host/CPU Interface  234  (ISA or PCI bus interface controller). These are industry-standard interface buses that include address decoder logics.  
           [0017]    Memory Controller  238  transfers host data between FIFO Buffer  236  to and from Display Memory  134  based on a reading or writing request from System/Host Bus  140 . When CPU  105  requests reading data, Memory Controller  238  receives read address from FIFO Buffer  236 . Memory Controller  238  issues read command to Display Memory  134  specifying received read address and executes reading. Memory Controller  238  returns the read data to FIFO Buffer  236 .  
           [0018]    When CPU  105  requests writing data, Memory Controller  238  receives write data and its address to store from FIFO Buffer  236  and issues write command to Display Memory using received write data and address. After finishing write operation, Memory Controller  238  checks next request from System/Host Bus  140  and enters next operation.  
           [0019]    Display/Scan Address Generator  237  generates the memory address for the display scan in order to read screen refresh data as display data to the display device. Memory Controller  238  reads the display data and transfers it to Attribute Controller  239 . These data transfers occur concurrently between Display Memory  134  to and from FIFO Buffer  236 , and Display Memory  134  to Attribute Controller  239 .  
           [0020]    Attribute Controller  239  may re-map or alter the color represented by the display data using a Register Color Look-Up Table and by outputting Pixel Data. Attribute Controller  239  may apply other attribute functions, such as blinking or reverse-video characters.  
           [0021]    RAM DAC  240  receives the Pixel Data. It is modified by Attribute Controller  239 . RAM DAC  240  contains RAM Color Look-Up Tables which are indexed by Pixel Data, and output digital values for red, green, and blue sub-pixels that comprise a color pixel. RAM DAC  240  also contains three digital-to-analog converters (DAC) that convert the digital color sub-pixel data to analog intensity values (analog RGB signals) that are transmitted to the CRT Display  210 . It also outputs CRT vertical and horizontal synchronous signals to CRT Display  210 .  
           [0022]    RAM DAC  240  output Digital Pixel Data to LCD Interface  241 . The Digital Pixel Data are taken from the output of RAM Color Look-Up Tables, after the RAM has been accessed and has output the digital sub-pixels, but before conversion to analog values. LCD Interface  241  may perform a gray-scale conversion of the color sub-pixels if the display device is STN LCD (Super Twisted Nematic Liquid Crystal Display). Or it may perform some other conversion of the Pixel Data to a format that is acceptable to LCD Display  220 . The converted pixel data is output from LCD Interface to the LCD Display  220 . LCD Interface  241  has LCD panel timing control signals and clock signals with the converted (digital) pixel data to the LCD Display  220 . LCD Display  220  may itself includes some additional control or conversion logic to manipulate the pixel data before it is displayed on a screen visually, and it may be implemented on many different types and in many different technologies.  
           [0023]    [0023]FIG. 2( b ) is an example of a frame buffer with a data compression scheme. This example frame buffer  280  uses publicly well-known CSC (color space conversion) scheme. The CSC compression scheme and motion picture frame buffer application are compatible, because original data format of motion picture images are usually video color space data format.  
           [0024]    Input data to the scheme are 18-bit RGB data and are converted to 6-bit YCrCb format (block  288 ) and written into memory block  281 . These data read out and recovered to 18-bit RGB data format (block  282 ) and output as FBDT after just one frame interval.  
           [0025]    The memory timing controller  286  and memory read/write control  284  blocks generate necessary memory control timing and address signals to execute just one frame time delay line between input to output data. The targeted compressed Frame Buffer size is 160 KB SRAM.  
         SUMMARY  
         [0026]    The invention in various embodiments discloses a composition/configuration in which blurring edges and residual images can be eliminated when displaying moving video images. The invention can provide, by using usual LCD back-light, without using special high speed and fast response liquid crystal material for the active matrix liquid crystal display, good quality moving display images without blurring edges and no residual image anomalies. The invention includes the use of a data emphasizer for outputting drive data to a LCD display and utilizes a back light control system in generating this drive data.  
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0027]    [0027]FIG. 1 is a block diagram of a computer system to explain the background of display sub-systems as they relate to computer systems.  
         [0028]    [0028]FIG. 2( a ) is a detailed view of a conventional display sub-system.  
         [0029]    [0029]FIG. 2( b ) is an example of a frame buffer with a data compression scheme.  
         [0030]    [0030]FIG. 3 illustrates a TFT LCD panel system block diagram according to at least one embodiment of the invention.  
         [0031]    [0031]FIG. 4 is an example of a DATA Emphasizer for an over-drive algorithm according to the invention.  
         [0032]    [0032]FIG. 5 illustrates an example of a DATA Emphasizer block detail for an adaptive over-drive algorithm.  
         [0033]    [0033]FIG. 6 illustrates an example of a DATA Emphasizer block for an adaptive over-drive algorithm with a BLPH signal input.  
         [0034]    [0034]FIG. 7 illustrates an example of a Conversion Table block for an adaptive over-drive algorithm with a BLPH signal input.  
         [0035]    [0035]FIG. 8 illustrates an example of a backlight timing generator.  
         [0036]    [0036]FIG. 9 illustrates a timing chart  900  of backlight related signals.  
         [0037]    [0037]FIG. 10 is an example of a Xenon tube backlight high voltage generator and trigger circuit  1000 .  
         [0038]    [0038]FIG. 11 is an exemplary embodiment of a DATA emphasizer for adaptive over-drive output with a BLPH input.  
         [0039]    [0039]FIG. 12 is an exemplary adaptive over-drive data and intensity timing chart.  
         [0040]    [0040]FIG. 13 exemplifies adaptive over-drive data and timing chart  1300  with BLPH control.  
         [0041]    [0041]FIG. 15 is another example of adaptive over-drive intensity timing chart  1500  with BLPH compensation control.  
         [0042]    [0042]FIG. 16 is an example of adaptive over-drive intensity timing chart  1600  with two lightings.  
         [0043]    [0043]FIG. 17 is an example of a video window detecting timing generator.  
         [0044]    [0044]FIG. 18 is a diagram of video window and display timing.  
     
    
     DETAILED DESCRIPTION  
       [0045]    The invention provides a means to drive the data for the value corresponding to the present frame display data and by comparing with the previous frame of display data, the display data in the present frame that has the changes, the display data are then over emphasized and written into the LCD driver with more than the amount of change to the pixel data. Furthermore, in connection with the display data that is emphasized previously, a means to apply emphasizing one after another frames and a means to change enhancement and compensation factor with two or more frames is provided. Furthermore, a backlight control means to control the lighting delay time, the lighting time width, the lighting interval, and the number of times of lighting within one frame of a liquid-crystal back lighting is provided. Furthermore, a means to change the above enhancement and compensation factors related between the liquid-crystal back lighting control of delay time, time width, interval, number of times and with the position on the screen of display data relative to backlight lighting control timing is provided. Without using extremely high-speed and fast response liquid crystal material, the residual image and blurring anomalies are eliminated, when moving video pictures or images are displayed. The invention provides TFT LCD liquid-crystal display devices with the ability to enable good screen and image quality for the moving images.  
         [0046]    Applications of the invention include:  
         [0047]    Use YUV and other compression algorithms for the frame buffer data.  
         [0048]    Xenon Strobo-flash tube can be used as a backlight light source.  
         [0049]    Allows several frame intervals to generate over-drive data and adaptive over-drive data (first over-drive data, second over-drive data, and third over-drive data).  
         [0050]    The over-drive data generation can be implemented in a display controller, separated from LCD panel controller, using the same emphasizing scheme/algorithm. Further, the techniques for over-drive data generation can be applied to any input data which is graphical in nature, such as those originating from a processing engine such as the CPU of a computer system, a dedicated graphics processor, or any component of an information or computer system.  
         [0051]    [0051]FIG. 3 illustrates a TFT LCD panel system block diagram according to at least one embodiment of the invention. Display Data is RGB 3×8-bit digital input and PCLK, DE, HS, and VS are timing input signals originating from the display controller coming through the LCD Interface (as shown in FIG. 2( a ).)  
         [0052]    DATA RCV block  360  receives input data and outputs this as needed to DATA Emphasizer  350 . TIMING RCV block  370  receives all timing signals and outputs these to TCON  345 , B/L (Backlight) CTL  335 , and Window Detect block  375  as needed. TCON  345  generates further internal timing control signals for DATA Emphasizer  350 , SOURCE DRIVER  311 , GATE DRIVER  313 , and LCD POWER  340 . LCD POWER block  340  includes a DC-to-DC converter and generates relatively high voltages for SOURCE DRIVER  311  and GATE DRIVER  313 .  
         [0053]    B/L CTL block  335  generates backlight control signals and outputs to a BLPS (backlight power supply inverter)  330 . BLPS  330  generates high voltage for backlight lighting. This voltage value depends on the type of backlight source  320  (e.g. CCFL tube, LED diode, or Xenon Strobo tube) that is used. Necessary electric power is supplied from available system voltage from computer system. LCD POWER  340  and BLPS  330  blocks convert the voltage to power all drivers and backlight source  320 .  
         [0054]    Window Detect block  375  detects the video window area based on given register value on the screen and sends a VIDEO WINDOW SIGNAL to DATA Emphasizer  350 . If VIDEO WINDOW is enabled, DATA Emphasizer  350  modifies incoming data in the VIDEO WINDOW. DATA Emphasizer  350  passes through display data outside VIDEO WINDOW (it does not perform data modification.). If VIDEO WINDOW is not enabled, DATA Emphasizer  350  modifies incoming data all over the screen.  
         [0055]    All necessary parameters for above operations are given by register values from the REGISTER block, which are written and read through a CTL INTF (control interface) by the system software as one of peripherals from a computer system such that those shown in FIG. 1.  
         [0056]    [0056]FIG. 4 is an example of a DATA Emphasizer for an over-drive algorithm according to the invention. Input data are 8-bit RGB (Red, Green and Blue) component data. This data-emphasizing block  400  is commonly applied to all R, G, or B data.  
         [0057]    FRAME BUFFER  410  makes a one frame time delay between its input to output with the bus width being 6-bit wide. The input data is referred to as IDDT (input display data) and output data of frame buffer  410  is referred to as FBDT (frame buffer data). The IDDT and FBDT become input to the CONV. TABLE  420 , which then accesses its internal memory (conversion table) and outputs 8-bit over-drive data. This conversion table  420  is configured to generate over-drive emphasizing data based on two IDDT and FBDT values. The output data is referred to as ODDT (over-drive data). LSB 2-bit data are multiplexed by MUX  440  and selected to output as ODDT LSB 2-bit. This MUX  440  select IDDT LSB 2-bit when IDDT=FBDT using CMP (comparator)  450  output equal signal. BUF logic  430  adjusts clock timing between ODDT and IDDT.  
         [0058]    If the two input data (IDDT and FBDT) are the same, output data becomes as the same value as the IDDT. If two input data are not the same, then the output data is converted based on the values (IDDT−FBDT) and FBDT.  
         [0059]    The output data (ODDT) is:  
           ODDT=IDDT+ ( IDDT−FBDT )×Factor Function ( IDDT, FBDT ) or  
           ODDT=IDDT+ Factor Function′ ( IDDT, FBDT ).  
         [0060]    The Factor Function (IDDT, FBDT) is variable function modeling TFT response time (RT-on and RT-off). This function decides how much to emphasize over-drive data and depends upon IDDT, FBDT, RT-on and RT-off values. The Factor Function′ (IDDT, FBDT) embeds the multiplied term (IDDT−FBDT) into the Factor Function (IDDT, FBDT), and eliminates the need for a multiply operation.  
         [0061]    If VIDEO WINDOW is enabled, this over-drive data emphasizer  400  modifies incoming data in the VIDEO WINDOW and it passes through display data outside of the VIDEO WINDOW. If VIDEO WINDOW is disabled, then all display data is emphasized to the LCD.  
         [0062]    [0062]FIG. 5 illustrates an example of a DATA Emphasizer block detail for an adaptive over-drive algorithm. The input data are 8-bit RGB data. This example has a different CONV. TABLE  520 , that additionally outputs MFBDT (modified frame buffer data, 6-bit) (in addition to the output of CONV. TABLE  420 ), and one MUX  530  for FRAME BUFFER  510  input data selection. The 6-bit conversion table  520  output is named AODDT (adaptive over-drive data). AODDT output can more accurately emphasize than ODDT data shown in FIG. 4. When IDDT and FBDT are not equal, AODDT and MFBDT are generated and MFBDT is selected to be written to FRAME BUFFER  510  for the next AODDT signal generation. MFBDT conversion table  520  output data are prepared to compensate (reverse direction emphasize) by feedback previous adaptive over-drive emphasizing data.  
         [0063]    The output data AODDT and MFBDT are:  
           AODDT=IDDT+ ( IDDT−FBDT ) * Adaptive Factor Function ( IDDT, FBDT ) or  
           AODDT=IDDT+ Adaptive Factor Function′ ( IDDT, FBDT ); and  
           MFBDT=IDDT+ ( IDDT−FBDT ) * Modify Factor Function ( IDDT, FBDT ) or  
           MFBDT=IDDT+ Modify Factor Function′ ( IDDT, FBDT ).  
         [0064]    Adaptive Factor Function (IDDT, FBDT) and Modify Factor Function (IDDT, FBDT) are variable functions of TFT response time, RT-on and RT-off. These functions decide how much to emphasize and compensate adaptive over-drive data from one frame to next frame and depends on IDDT, FBDT, RT-on and RT-off. In some embodiments of the invention, the multiplication of the term (IDDT−FBDT) by each of the Modify Factor Function and Adaptive Factor Function can be embedded therein such that different functions Modify Factor Function′ and Adaptive Factor Function′ can be used respectively, instead, thereby eliminating the necessity of a multiply operation.  
         [0065]    If VIDEO WINDOW is enabled, this adaptive over-drive data emphasizer  500  modifies incoming data in the VIDEO WINDOW and it passes through display data outside of the VIDEO WINDOW. If VIDEO WINDOW is disabled, then all display data for the LCD is modified.  
         [0066]    [0066]FIG. 6 illustrates an example of a DATA Emphasizer block for an adaptive over-drive algorithm with a BLPH signal input. DATA Emphasizer  600  has an additional CONV. TABLE  620  input BLPH (backlight phase) signal  640  which indicates relative position change with backlight lighting timing. AODDT and MFBDT is adjusted to their optimum values using this BLPH and depending on-the screen line positioning relative to the backlight lighting timing. Appendices A and B show representative AODDT where BLPH=0, and BLPH=1, respectively. Appendix C shows representative MFBDT.  
         [0067]    [0067]FIG. 7 illustrates an example of a Conversion Table block for an adaptive over-drive algorithm with a BLPH signal input. A Conversion Table (CONV. TABLE  420 ) for first over-drive data generating algorithm does not have MFBDT output, while it would so for an adaptive over-drive data generating algorithm (according to CONV. TABLE  520 ). The BLPH signal  640  can be eliminated, if the system does not use backlight phase data compensation.  
         [0068]    Conversion Table  620  has adaptive over-drive data and backlight compensation inputs that are three sets of input color signals (6-bit FBDT and 6-bit IDDT for each RED, GREEN, and BLUE) and a one-bit BLPH signal  640  which access the Table  620  through address lines  723   a . The BLPH signal  640  is common to RED, GREEN, and BLUE conversion sub-tables which make up the Conversion Table  620 . There are three memory conversion sub-tables  620   a ,  620   b , and  620   c  within Conversion Table  620  for each RED, GREEN, and BLUE components, respectively. The outputs are also three sets of 6-bit MFBDT and 6-bit AODDT data, each set corresponding to one of Red, Green and Blue which are accessed by output lines  725   a . The conversion sub-tables  620   a ,  602   b , and  620   c  are readable/writeable memory and the system can change the data therein using register read and write operation through conversion table read/write control block  730 .  
         [0069]    [0069]FIG. 8 illustrates an example of a backlight timing generator. Input signals to generator  800  are timing signals from TIMING RCV block  370  (see FIG. 3). Using these timing signal inputs, FRAME START DETECT logic  840  detects VDE (vertical display enable timing) from VS (vertical synchronous signal) and a DE (Display Enable signal). This detection resets and restarts all counters in generator  800 . A DELAY (D) COUNTER  820  counts delay intervals by counting HS (Horizontal synchronous signal) as the unit timing clock signal. An INTERVAL (T) GENERATOR  830  starts counting after receiving a signal from DELAY (D) COUNTER  820 . ACTIVE TIME (W) GENERATOR  810  starts counting after receiving signals from both DELAY (D) COUNTER  820  and INTERVAL (T) GENERATOR  830  ACTIVE TIME (W). GENERATOR  810  generates a BLON signal for the backlight turn-on width signal and BLPH signal for the backlight phase signal.  
         [0070]    If the backlight source is an LED (Light Emitting Diode) backlight, three BLON signals are prepared for RGB backlight LEDs, because LED backlights need to control color balance by adjusting each active time width. CCFL tube and Xenon tube backlights can function with only one BLON output signal. All of the above counters ( 810 ,  820  and  830 ) can be implemented with necessary parameter registers to control delay, width, and interval timings independently.  
         [0071]    [0071]FIG. 9 illustrates a timing chart  900  of backlight related signals. Signal VS is the one of the timing input signals to the LCD Panel and it indicates the frame start timing and interval. The FRAME START DETECT block  840  detects the first DE signal after a VS and generates a VDE (Vertical Display Enable). The signal VDE starts all backlight control timing counters. DELAY (D) COUNTER  820  counts backlight on timing delay D 0  and activates the first BLON pulse of width W 0  and INTERVAL (T) GENERATOR  830 . The output pulse from INTERVAL (T) GENERATOR  830  activates thereafter and follows with the BLON pulse. The BLPH signal is generated the same way and pulses at delay time D p  with a width W p . BLON and BLPH have intervals T and a repeat time of N as their common parameters. The BLON pulse turns on LED and CCFL backlight and triggers the Xenon Strobo flash. LED backlights need to have three BLON signals for R, G, and B lighting independently to control color balance.  
         [0072]    A narrower BLON pulse (shorter W 0 ) makes for a sharper edge because a tracing human eye feels the display image at the BLON (W 0 ) timing, wherein backlight is turned on. It avoids accumulation of edge images that cause blurring, if the BLON pulse is a narrow pulse.  
         [0073]    Xenon strobo flash backlight makes very narrow impulse lighting and it simulates CRT display flushing. It is an ideally narrow flush lighting backlight which can eliminate blurring of the edges of motion picture in an LCD panel.  
         [0074]    Multiple BLON (W 0 ) timing makes for a sharper and brighter feeling, because the sum total of lighting becomes greater. It equalizes artifacts of image position on display screen and backlight phase relationships all over the screen. It also eliminates screen flicker sensation completely.  
         [0075]    As mentioned, the BLPH is a DATA Emphasizer control signal to adjust/compensate screen vertical position and backlight blink timing relative artifacts. Blinking backlight, using the BLON signal to turn on the backlight, can reduce temperature increases and average power consumption. Thus, this scheme can accommodate a higher voltage and more current. It can make for better lighting efficiency by averaging the effect in contrast with a normal continuously on backlight scheme. Multiple BLON and BLPH controls have the same effect in that they remove artifacts of backlight blink timing and relative screen position LCD drive timing.  
         [0076]    [0076]FIG. 10 is an example of a Xenon tube backlight high voltage generator and trigger circuit  1000 . HI Voltage DC-to-DC Converter  1010  generates enough voltage to flash xenon strobo tube X 1 . Capacitor C HV  makes a flattened and smoothed high voltage power source. Electric energy is charged into capacitor C F  through resistor R F . C F  and R F  create a time constant of charging speed which is designed to follow the flashing period T. The discharging electric energy charges into capacitor C F  with flashing period T, and is designed to meet xenon tube X 1 . R L  is a leaking resistor to discharge electric energy in capacitor C F  when the system is power off.  
         [0077]    Triggering circuit  1020  is designed to meet flash period T and generates enough high voltage to trigger tube X 1 . BLON signal controls only triggering timing (lighting start timing). The width information is not used by circuit  1020 . DC-to-DC converter  1010  (or an inverter) for LED backlight and CCFL tube backlights may be implemented by using well-known designs.  
         [0078]    [0078]FIG. 11 is an exemplary embodiment of a DATA emphasizer for adaptive over-drive output with a BLPH input. CONV. TABLE  1120  takes as inputs frame buffer data FBDT that is 4 bits (rather than 6 bits as shown in FIG. 6) and the 4 MSBs (most significant bits) of the incoming display data IDDT (which is 8 bit RGB) as other input data. The 4 LSBs (least significant bits) of the incoming display data is sent to BUF  1130  for possible selection by MUX  1140 . FRAME BUFFER  1110  buffers either 4 bit MFBDT (modified frame buffer data) from the previous cycle output from CONV. TABLE  1120  or the 4 MSBs of the incoming display data. This selection is performed by a MUX  1160  and is controlled by the EQUAL signal output by CMP  1150 . CMP  1150  generates an EQUAL signal at if true the 4 MSBs of IDDT and FBDT are equal and returns false if they are not. If EQUAL is true, then MUX  1150  selects the 4 MSBs of the incoming display data and if not, then selects the MFBDT feedback of the previous cycle. Likewise, if EQUAL is true, MUX  1140  selects the 4 LSBs of the FDDT which is buffered through BUF  1130  and otherwise selects the AODDT output (4 LSBs thereof) from CONV. TABLE  1120 .  
         [0079]    [0079]FIG. 12 is an exemplary adaptive over-drive data and intensity timing chart. This chart  1200  shows the comparison of LCD intensity change and drive data waveforms as among normal drive, over-drive, and adaptive over-drive data types.  
         [0080]    The first frame interval shows start drive data and start level (tone or intensity) from previous frame before a picture is moving. The second frame to the fourth frame intervals show incoming display data changing to a target level as well as drive data waveforms and intensity change curves depending on each drive scheme. The fifth frame interval shows all intensity curves convergent to the target level.  
         [0081]    The long-dashed line and curve shows normal drive data and its LCD intensity response. The normal drive data is applied as target drive data to the LCD without modification. Its LCD intensity response curve shows slow steady progression to the target level. This rising speed is the LCD panel native response time (T ON  or T OFF ). This example shows that it takes 3 frames to reach target level.  
         [0082]    The short-dashed line and curve shows over-drive data and its LCD intensity response. The over-drive data is applied emphasized drive data in the second frame interval (the first frame of picture move) to speed up its LCD intensity response. This example shows that it takes 2 frames to reach target level.  
         [0083]    The solid line and curve shows adaptive over-drive data and its LCD intensity response. The adaptive over-drive data applies a stronger emphasizing drive than does over-drive data in the second frame interval (the first frame of the picture&#39;s move) to make it over-shoot the desired response. Then, in the third frame the adaptive over-drive data compensates the over-shooting in the opposite direction and converges quickly to the target. This example shows that it takes less than one frame to reach target level. As mentioned above, the CONV. TABLE output, AODDT and MFBDT. When the system detects a picture move (i.e. a IDDT and FBDT change), then MFBDT is written to the FRAME BUFFER. In the next frame interval, the MFBDT is read and is compared with IDDT and output for the next emphasizing/compensation data and MFBDT. This data emphasizing operation repeats and perform adaptive over-drive until convergence occurs to the target level.  
         [0084]    [0084]FIG. 13 exemplifies adaptive over-drive data and timing chart  1300  with BLPH control. The solid curve shows adaptive over-drive intensity response with BLPH=0 and this intensity waveform is from the 2nd ⅕ th  of the screen area of the LCD panel. The dashed curve shows adaptive over-drive intensity response with BLPH ( 1310 )=1 and this intensity waveform is from 4th ⅕ th  of the screen area of the LCD panel.  
         [0085]    When BLPH ( 1310 )=1, over-shooting of adaptive over-drive becomes smaller than BLPH ( 1310 )=0. In this figure, the BLON waveform indicates backlight on timing and BLPH waveform indicates CONV. TABLE control signal from backlight control block. Because the human eye sees LCD intensity when BLON=1 (when backlight is on), the part labeled by left-to-right, up-sloping diagonal hatching is the intensity for the 2nd ⅕ th  of screen area of the LCD panel after one frame of a picture move and the part labeled by left-to-right down-sloping diagonal hatching is the intensity for the 4th ⅕ th  of screen area. The average intensity of both areas would appear as the same intensity as target level. Using BLPH  1310 , the data emphasizer modification can hide over-shooting. This pattern  1400  as it relates to the BLPH signal is shown in FIG. 14.  
         [0086]    [0086]FIG. 15 is another example of adaptive over-drive intensity timing chart  1500  with BLPH compensation control. The dashed line curve shows adaptive over-drive intensity response with BLPH=1 and this intensity waveform is from 4th ⅕ th  of screen area of the LCD panel the same as that shown in FIGS. 13 and 14. The solid line curve shows another adaptive over-drive intensity response with BLPH=1 and this intensity waveform is from 4th ⅕ th  of screen area of the LCD panel as well. It exhibits more over-shooting of the intensity waveform than adaptive over-drive intensity response with BLPH=0 from the 2nd ⅕ th  of screen area of the LCD panel. The average intensity of diagonally hatched areas appears to be identical in intensity to the target level. It shows less than one frame is needed to reach the target level and looks quicker to converge than the normal drive waveform. Appendices A and B show representative AODDT where BLPH=0, and BLPH=1, respectively.  
         [0087]    [0087]FIG. 16 is an example of adaptive over-drive intensity timing chart  1600  with two lightings. The part  1610  of chart  1600  is the intensity waveform for the 2nd ⅕ th  of screen area of the LCD panel and the part  1620  is the intensity waveform for the 4th ⅕ th  of screen area when the backlight is on. The average intensity looks the same between two areas, because the backlight is on two times in one frame and the relative phase relationship between backlight timing and driving timing become the same. It occurs in all LCD display areas to equalize the human eye&#39;s intensity feeling, if the number of times for backlight-on increases to more than once. Multiple backlight flashing makes for a brighter screen and sharper image edge, because such backlight-on timing can make narrower response and total backlight on time becomes longer.  
         [0088]    [0088]FIG. 17 is an example of a video window detecting timing generator. Pixel Counter  1710  is reset by the HS signal and counts up by PCLK when DE=1 and generates the current horizontal screen position count of incoming display data. This number is compared by P-CNT Comparator  1720  with VWXPOS Register (XSP &amp; XEP)  1770  and generates video window horizontal signal between XSP and XEP position (video window X start position and X end position). Line Counter  1730  is reset by the VS signal and counts up according to the DE ON signal when VDE=1 and generates the current vertical screen position count of incoming display data. This number is compared with the value from VWYPOS (YSP &amp; YEP) Register  1760  by L-CNT Comparator  1740  and generates video window vertical signal between YSP and YEP position (video window Y start position and Y end position). The video window horizontal signal and video window vertical signal are ANDed together (block  1750 ) to generate the complete video window signal.  
         [0089]    [0089]FIG. 18 is a diagram of video window and display timing. The display scan starts from top-left corner (line number=0 and DE=1) and scans horizontally left to right. When DE becomes 0, HRT (horizontal retrace) starts. HS (Horizontal Sync.)  1830  turns on and off in between horizontal retrace timing. It repeats to finish the whole display screen line (VDE becomes 0) and then VRT (vertical retrace) starts. VS (Vertical Sync.)  1820  turns on and off at the starting edge of HS  1830  in the VRT (vertical retrace timing) interval. The Video Window  1810  is defined by VWXPOS (XSP &amp; XEP) for its horizontal position and VWYPOS (YSP &amp; YEP) for its vertical position.