Patent Publication Number: US-2007103421-A1

Title: Liquid-crystal display, projector system, portable terminal unit, and method of driving liquid-crystal display

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a liquid-crystal display for time-division-writing video signals for one pixel row and driving method, a projector system on which the liquid-crystal display is mounted, and a portable terminal unit.  
      2. Description of Related Art  
      A liquid-crystal projector provided with three liquid-crystal displays corresponding to three primary colors of red (R), green (G), and blue (B) can display a video of a high-luminance, high-definition, and large-screen video. Therefore, the liquid-crystal display is the mainstream of projectors.  
      A liquid-crystal display used for this liquid-crystal projector normally uses a monochromatic liquid-crystal display in which the diagonal of a display screen is 2″ or less in order to decrease the projector in size and cost. Particularly, because a liquid-crystal display using a P—Si (polysilicon)-TFT (Thin film transistor) has a high mobility of its P—Si-TFT as a pixel transistor formed on each pixel, it is possible to constitute a part of a peripheral circuitry by a TFT on a glass substrate same as pixels. Thereby, a liquid-crystal display provided with a P—Si-TFT is the mainstream of liquid-crystal displays for projectors because it is possible to decrease the display in size and simplify an interface.  
      As one of the driving methods of this liquid-crystal display, there is a block division driving method (for example, JP6-80477: reference 1). The block division driving method is a method for grouping a plurality of data lines of a liquid-crystal display into a plurality of blocks (groups) and writing video signals for each block.  
       FIG. 28  is a block diagram showing a conventional liquid-crystal display using a P—Si-TFT. As shown in  FIG. 28 , in the case of this liquid-crystal display, a TFT-side glass substrate (not illustrated) and an opposite-side glass substrate (not illustrated) are set in parallel and a liquid-crystal layer (not illustrated) is set between the both substrate. Moreover, as shown in  FIG. 28 , data lines D 1  to D 9  (also generally referred to as data lines D) are set in the row direction on the TFT-side glass substrate and gate lines G 1  to G 6  (generally referred to as data lines G) are set in the column direction on the same TFT-side glass substrate. Moreover, a pixel is formed for every most proximity points between the data lines D 1  to D 9  and the gate lines G 1  to G 6 . That is, a plurality of pixels are arranged like a matrix.  
      One pixel thin-film transistor TFT, storage capacitor Cs, and pixel electrode Ep are set on each pixel. Either of the source and drain of the pixel thin-film transistor is connected to the data lines D, the other of them is connected to one-hand electrode of the storage capacitor Cs and the pixel electrode Ep. The gate of the TFT is connected to the gate lines G. Moreover, a ground potential is applied to the other-hand electrode of the storage capacitor Cs. Furthermore, a common electrode Eo is set to a position corresponding to each pixel on the opposite-side glass substrate and a pixel capacitor Clc is formed between the pixel electrode Ep and the common electrode Eo.  
      Furthermore, a data driver circuitry  101  for driving the data lines D and a gate driver circuitry  102  for driving the gate lines G are formed at the outside of a region in which a plurality of pixels are formed on the TFT-side glass substrate. A shift register  103  and analog switches SW 1 - 1  to SW 3 - 3  (hereafter generally referred to as ASW) are set on the data driver circuitry  101 . Furthermore, each data line D is connected to any one of video signal lines V 1  to V 3  through the ASW.  
      Specifically, the data line D 1  is connected to the video signal line V 1  through the switch SW 1 - 1 , a data line D 2  is connected to a video signal line V 2  through the switch SW 1 - 2 , a data line D 3  is connected to a video signal line V 3  through the switch SW 1 - 3 , a data line D 4  is connected to the video signal line V 1  through a switch SW 2 - 1 , a data line D 5  is connected to the video signal line V 2  through a switch SW 2 - 2 , a data line D 6  is connected to a video signal line V 3  through a switch SW 2 - 3 , a data line D 7  is connected to the video signal line V 1  through a switch SW 3 - 1 , a data line D 8  is connected to the video signal line V 2  through a switch SW 3 - 2 , and a data line D 9  is connected the video signal line V 3  through a switch SW 3 - 3 .  
      A plurality of data lines D, for example, three data lines D adjacent to each other form a block and ASWs in the same block are controlled by the same control signal.  FIG. 28  shows an example in which three data lines belong to one block and there are three blocks. Control signals for controlling ASWs use output signals SR 1  to SR 3  of the shift register  103 . For example, switches SW 1 - 1  to SW 1 - 3  belonging to one block are controlled by the control signal SR 1 .  
      Then, a shift register  104  is set to the gate driver circuitry  102  and output terminals of the shift register  104  are connected to gate lines G.  
      Then, operations of this liquid-crystal display are described below.  FIG. 29  is a timing chart showing operations of the data driver circuitry shown in  FIG. 28  and  FIG. 30  is a timing chart showing operations of the gate driver circuitry shown in  FIG. 28 . In  FIG. 29 , a period TH shows one horizontal period for writing a video signal in pixels for one row whose writing is controlled by one gate line of the liquid-crystal display.  
      In this horizontal period TH, the gate driver circuitry  102  outputs a high-level signal to one gate line Gn and selects the one gate line Gn. Moreover, the shift register  103  of the data driver circuitry  101  successively outputs a control signal for controlling ASWs of each block synchronously with a horizontal sync signal HSYNC input from the outside. Moreover, because video signals are supplied to video signal lines D 1  to D 3  synchronously with outputs of the shift register  103 , video signals are sampled by the data lines D for each block. In  FIG. 29 , because three data lines D are included in one block, video signals are written for every three data lines D. Furthermore, in this case, because a potential for turning on a pixel transistor TFT is written in one selected gate ling G, the video signals sampled y the data lines are written in the pixel capacitor Clc and storage capacitor Cs through the pixel transistor TFT.  
      Furthermore, the period TV shown in  FIG. 30  shows one vertical period for writing video signals for one screen of a liquid-crystal display. In the vertical period TV, the gate driver circuitry  102  successively writes voltages for turning on a pixel transistor TFT in gate lines G one by one synchronously with a vertical sync signal VSYNC input from the outside. By performing these operations, it is possible to display a two-dimensional video on the liquid-crystal display.  
      Thus, an advantage of the block division driving method is that the number of terminals for connecting a liquid-crystal display with external circuits can be greatly decreased. The number of terminals required to operate a data driver circuitry and a gate driver circuitry is 10 or less including a power supply and the number of video signal wirings is 30 or less even when the resolution of the liquid-crystal display exceeds XGA (length 1,024×width 768). That is, by connecting approx. 50 terminals, it is possible to drive a liquid-crystal display having a resolution exceeding XGA. However, in the case of a liquid-crystal display using an a-Si (amorphous silicon) TFT used for a display of a notebook-size personal computer, it is necessary to connect 3,000 terminals or more in order to drive a liquid-crystal display having the same resolution. However, by performing block division driving, it is possible to greatly decrease the number of terminal connections compared to the case of the liquid-crystal display using the a-Si TFT.  
      In addition to the above block division driving method, a method using COG (chip on glass) connection is considered which directly connects an IC (Integrated Circuitry) for supplying a video signal to a data line onto a glass substrate as a method for decreasing the number of connection terminals to a liquid-crystal display.  FIG. 31  is a block diagram showing a conventional liquid-crystal display using the COG connection. The liquid-crystal display using the COG is a system frequently used at present as a display for a portable unit.  
      As shown in  FIG. 31 , in the case of this liquid-crystal display, the configuration of a gate line, data line, pixel, and gate driver circuitry is the same as the case of the liquid-crystal display shown in  FIG. 28 . Moreover, instead of the data driver circuitry  101  shown in  FIG. 28 , a data line driving IC  111  is mounted on a TFT-side glass substrate (not illustrated). A plurality of video signal lines V 1  to V 3  are set to the data line driving IC  111  and the video signal lines are connected to a plurality of data lines D through ASWs. A plurality of ASWs connected to one output terminal (video signal line V) of the data line driving IC  111  are controlled by different control lines SP 1  to SP 3 . Though not illustrated, a signal and a power supply for operating the data line driving IC  111  are supplied from the outside through electric wirings arranged on the glass substrate of the liquid-crystal display.  
      By using the above configuration, the number of connection terminals required to operate the liquid-crystal display is formidably small compared to an a-Si TFT liquid-crystal display because the number of terminals for operating the gate driver circuitry  102  is approx. 10 and the number of terminals for operating the data line driving IC  111  is approx. 100.  
      Then, operations of this liquid-crystal display are described below.  FIG. 32  is a timing chart showing operations of the data line driving IC shown in  FIG. 31 , which is an illustration showing operations of one horizontal period. As shown in  FIG. 32 , one horizontal period TH is divided into three periods of TB 1  to TB 3 . In the period TB 1 , the potential of a control line SP 1  becomes a potential for turning on an ASW and the ASW connected to the control line SP 1  is turned on and a video signal is written in a data line D. Thereafter, in the period TB 2 , the ASW connected to the control line SP 2  is turned on and in the period TB 3 , the ASW connected to the control line SP 3  is turned on, and a video signal is written in the data line D connected to each ASW. Thus, when assuming a plurality of data lines connected to one output terminal of the data line driving IC  111  through ASWs as one block, video signals are successively written in data lines in the block in time division and this operation is simultaneously performed in all blocks.  
      However, the above prior art has the following problem. It is clarified that a liquid-crystal display for performing the above block division driving and a liquid-crystal display according to COG connection have a problem that a display image quality is deteriorated.  
      In the case of the block division driving method, even when writing video signals having the same luminance in a portion at an end of a block in which video signals are written in blocks and in a portion other than the former portion, a luminance difference occurs and the difference is recognized as streak-like irregularity.  FIG. 33  is an equivalent circuitry showing a configuration nearby an ASW of a liquid-crystal display for performing the block division driving shown in  FIG. 28 . As already described, in the case of this liquid-crystal display, video signals are written in data lines in blocks in one horizontal period. A block to be controlled by the control signal SR 2  is noticed. Video signals are written in the data lines D 4 , D 5 , and D 6  belonging to this block in the period TB 2  and ASWs (switches SW 2 - 1  to SW 2 - 3 ) are returned to a turned-off state at the end of the period. Then, in the period TB 3 , writing of video signals in the data lines D 7 , D 8 , and D 9  is started.  
      In this case, the capacitive coupling by a parasitic capacitance Cp  6 - 7  is present between the data lines D 6  and D 7 . When a signal is written in the data line D 7  and its potential is fluctuated, the potential of the data line D 6  is also fluctuated in accordance with the fluctuation of the former potential. Because this phenomenon occurs in all blocks, the potential of a data line at a block boundary portion becomes a potential shifted from the potential of a written signal. It is a matter of course that a parasitic capacitance between data lines is present not only between adjacent data lines but also between data lines separate from the adjacent data lines. Speaking strictly, an error occurs in potentials of all data lines. Because the magnitude of a parasitic capacitance is maximized between adjacent wirings, an error voltage of a data line located at the boundary portion between blocks is maximized. Because the error voltage causes a luminance difference between pixels and the luminance difference influences all pixels on the same data line, streak-like irregularity along a data line is generated.  
      For this problem, the present inventor develops a method for decreasing a parasitic capacitance between data lines and decrease streak-like irregularities by applying a shield to a data line and discloses the method in JP No. 3428511. However, it is difficult to completely eliminate parasitic capacitances. When increasing the number of gradations to be displayed on a liquid-crystal display, there is a case in which a streak-like irregularity can be slightly recognized.  
      Moreover, also in the case of a liquid-crystal display according to COG connection, a problem occurs that a pixel column connected to one of a plurality of data lines connected to one output terminal of a data line driving IC is different from other pixel column in luminance and the luminance appears as streak-like irregularity. This cause is described by referring to  FIG. 34 .  FIG. 34  is equivalent circuitry showing a configuration nearby an ASW of a liquid-crystal display according to the COG connection shown in  FIG. 31 . As already described, the circuitry performs an operation that one output of data line driving circuitry time-division-writes data in three data lines in one horizontal period.  
      The data lines D 4  to D 6  connected to the video signal line V 2  of the data line driving IC  111  (refer to  FIG. 31 ) are noticed. A signal is written in the data line D 4  in the period TB 1  and thereafter, the ASW SW 2 - 1  is turned off, and the data line D 4  becomes floating. Then, in the period TB 2 , a signal is written in the data line D 5 . Then, potential fluctuation due to writing of a signal in the data line D 5  causes potential fluctuation of the data line D 4  due to capacitive coupling by a parasitic capacitance Cp 4 - 5 .  
      Then, in the period TB 3 , a signal is written in the data line D 6 . By the influence of this writing, potential fluctuation occurs in the data lines D 5  and D 7 . Moreover, in this period, because a signal is also written in the data line D 3 , the data line D 4  is influenced by writing of the signal. That is, the data line D 4  receives potential fluctuation due to writing of signal in the data lines D 5  and D 3  and the data line D 5  is influenced by the potential fluctuation due to writing of signal in the data line D 6 . The data line D 6  is not influenced by potential fluctuation because a signal is not written in adjacent data lines D 5  and D 7  after completing signal writing. Also in this case, speaking strictly, a parasitic capacitance between data lines does not occur only between adjacent data lines. However, a parasitic capacitance between adjacent data lines most influences the potential of a certain data line.  
      Thus, because the way of receiving potential fluctuation due to writing of a signal in other data line is different between a plurality of data lines to be driven by the same output terminal of data line driving circuitry, a streak-like irregularity occurs similarly to the case of a liquid-crystal display for performing block division driving. However, a liquid-crystal display according to COG connection is used for a direct-sight for a small portable terminal provided with color filters of R, G, and B. Particularly, when the color filters are arranged like a stripe along data lines and the number of data lines to be driven by one output of a data line driving IC is 3, even if voltage fluctuation occurs due to parasitic capacitances of the data lines, it is difficult to recognize the voltage fluctuation as streak-like irregularity because a luminance change is equal between data line of the same color and therefore, it has not been recognized as a problem. However, when setting the number of time divisions to 3 or more (for example, multiple of 3) and using a three-plate-type projector without adding a color filter, this becomes a large problem similarly to the case of a liquid-crystal display for performing block division driving.  
     SUMMARY OF THE INVENTION  
      The present invention is made to solve the above-discussed problems and has as an objective to eliminate streak-like irregularity due to time-division writing in a liquid-crystal display for writing video signals for one pixel row by time-dividing the signals, its driving method, and a projector system on which the liquid-crystal display is mounted, and a portable terminal unit.  
      A liquid-crystal display of the present invention comprises (n×m)(n and m are integers of 2 or more) data lines extending in the row direction and divided into m groups for every n lines adjacent to each other, a plurality of gate lines extending in the column direction, a plurality of pixels set for every proximity point between the data line and the gate line, gate driver circuitry for successively selecting the gate lines in one vertical period for displaying images for one screen, and data driver circuitry for outputting video signals for one pixel row to the data lines in one horizontal period in which the gate driver circuitry selects one of the gate lines, wherein the data driver circuitry has m output terminals set for every above group to output the video signals, the k-th (k is an integer of 1 to n) switch for switching whether to connect the k-th data line in each group to the output terminals, n k-th control lines connected to all the k-th switches in common, and driving circuitry for successively outputting a control signal for turning on the k-th switches to the k-th control lines and the driving circuitry differentiates a sequence for outputting the control signals to the n control lines in the horizontal period for predetermined period.  
      In the case of the present invention, it is possible that by differentiating a sequence for outputting a control signal to n control lines belonging to each group in a horizontal period for predetermined period, a sequence for outputting video signals to data lines belonging to each group in a horizontal period is differentiated for predetermined period, a data line in which potential is fluctuated is fluctuated for predetermined period, and only the potential of a data line set to a specific position in each group is prevented from being fluctuated. Thereby, when viewing the whole image, it is possible to eliminate streak-like irregularity. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a block diagram showing the liquid-crystal display of the first embodiment of the present invention.  
       FIG. 2  is a timing chart showing operations of the liquid-crystal display of the first embodiment in a certain vertical period by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 3  is a timing chart showing operations of the liquid-crystal display of the first embodiment in a vertical period next to the vertical period shown in  FIG. 2  by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 4  is a timing chart showing operations of the liquid-crystal display of the first embodiment in a vertical period next to the vertical period shown in  FIG. 3  by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 5  is a timing chart showing operations of the liquid-crystal display of the second embodiment of the present invention in a certain vertical period by assigning time to the axis of abscissa and potential of each wiring.  
       FIG. 6  is a timing chart showing operations of the liquid-crystal display of the second embodiment in a vertical period next to the vertical period shown in  FIG. 5  by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 7  is a timing chart showing operations of the liquid-crystal display of the second embodiment in a vertical period next to the vertical period shown in  FIG. 6  by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 8  is a block diagram showing the liquid-crystal display of the third embodiment of the present invention.  
       FIG. 9  is a timing chart showing operations of the liquid-crystal display of the third embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 10  is a block diagram showing the liquid-crystal display of the fourth embodiment of the present invention.  
       FIG. 11  is circuitry diagram showing the gate driver circuitry of the fourth embodiment.  
       FIG. 12  is a block diagram showing the data-line driving circuitry of the fourth embodiment.  
       FIG. 13 a  sectional view showing the liquid-crystal display of the fourth embodiment.  
       FIG. 14  is a timing chart showing operations of the data driver circuitry of the liquid-crystal display of the fourth embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 15  is a timing chart showing operations of the data driver circuitry of the liquid-crystal display of the fourth embodiment in a certain vertical period by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 16  is a timing chart showing operations of the data driver circuitry of the liquid-crystal display of the fourth embodiment in a vertical period next to the vertical period in  FIG. 15  by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 17  is a timing chart showing operations of the data driver circuitry of the liquid-crystal display of the fourth embodiment in a vertical period next to the vertical period in  FIG. 16  by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 18  is a timing chart showing operations of the data driver circuitry of the liquid-crystal display of the fifth embodiment of the present invention by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 19  is a timing chart showing operations of the data driver circuitry of the liquid-crystal display of the sixth embodiment of the present invention in a vertical period next to the vertical period in  FIG. 18  by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 20  is a timing chart showing operations of the data driver circuitry of the liquid-crystal display of the sixth embodiment in a vertical period next to the vertical period in  FIG. 19  by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 21  is a block diagram showing the liquid-crystal display of the seventh embodiment of the present invention.  
       FIG. 22  is a timing chart showing operations of the signal processing circuitry of the seventh embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 23  is an illustration showing the polarity of a video signal to be applied to the pixel electrode of each pixel in a certain vertical period.  
       FIG. 24  is an illustration showing the polarity of a video signal to be applied to the pixel electrode of each pixel in a vertical period next to the vertical period in  FIG. 23 .  
       FIG. 25  is a timing chart showing operations of the liquid-crystal display of the eighth embodiment of the present invention by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  
       FIG. 26  is a block diagram showing the projector system of the ninth embodiment of the present invention.  
       FIG. 27  is a block diagram showing the liquid-crystal display of the tenth embodiment of the present invention.  
       FIG. 28  is a block diagram showing a conventional liquid-crystal display using a P—Si-TFT.  
       FIG. 29  is a timing chart showing operations of the data driver circuitry shown in  FIG. 28 .  
       FIG. 30  is a timing chart showing operations of the gate driver circuitry shown in  FIG. 28 .  
       FIG. 31  is a block diagram showing a conventional liquid-crystal display using COG connection.  
       FIG. 32  is a timing chart showing operations of the data-line driving IC-shown in  FIG. 31 .  
       FIG. 33  is equivalent circuitry diagram showing a configuration nearby an ASW of a liquid-crystal display for performing the block division driving shown in  FIG. 28 .  
       FIG. 34  is equivalent circuitry diagram sowing a configuration nearby an ASW portion of a liquid-crystal display using the COG connection shown in  FIG. 31 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
      According to the present invention, it is possible to disperse data lines whose potentials are fluctuated for every vertical period and prevent only the potential of a data line set to a specific position from fluctuating in each group by differentiating a sequence for outputting video signals to data lines belonging to each group in a horizontal period for every vertical period. Thereby, it is possible to eliminate streak-like irregularity.  
      In the case of the present invention, it is possible to fluctuate data lines whose potentials are fluctuated for every horizontal period or a plurality of horizontal periods by differentiating a sequence for outputting control signals to n control lines in a horizontal period for every horizontal period of one time or a plurality of times and prevent only the potential of a data line set to a specific position in each group from fluctuating. Thereby, it is possible to eliminate streak-like irregularity.  
      The driving circuitry may differentiate a sequence for outputting the control signals to the n control lines in the horizontal period for every above horizontal period of one time or a plurality of times. Thereby, it is possible to fluctuate the sequence not only for every vertical period but also for every horizontal period of one time or a plurality of times. Therefore, it is possible to more effectively eliminate streak-like irregularity.  
      Moreover, the liquid-crystal display may have a signal processing circuitry. The signal processing circuitry includes a memory which stores video signals input from a signal source for at least one screen. The signal processing circuitry reads the stored video signals for one screen at a frequency t times (t is an integer of 2 or more) higher than a frequency when input from a signal source, and outputs the read video signals to the data driver circuitry t times in a period in which video signals for the next one screen are input. Thereby, by performing display in accordance with a temporally compressed video signal output from the signal processing circuitry, it is possible to more frequently change the sequence for outputting control signals to n control lines in a horizontal period. Thereby, it is possible to more securely prevent streak-like irregularity.  
      Embodiments of the present invention are specifically described below by referring to the accompanying drawings. First, first embodiment of the present invention is described.  FIG. 1  is a block diagram showing the liquid-crystal display of this embodiment. As shown in  FIG. 1 , in the liquid-crystal display  1 , a TFT-side glass substrate (not illustrated) and an opposite-side glass substrate (not illustrated) are set in parallel with each other and a liquid-crystal layer (not illustrated) is formed between the both substrates.  
      Moreover, data lines D 1  to D 9  (also generally referred to as data lines D) extending in the row direction are set on the TFT-side glass substrate and gate lines G 1  to G 6  (also generally referred to as data lines G) extending in the column direction are set on the same TFT-side glass substrate. Furthermore, a pixel  2  is formed at each of proximity points between the data lines D 1  to D 9  and the gate lines G 1  to G 6 . That is, in the case of this liquid-crystal display, a plurality of pixels are arranged like a matrix.  
      One pixel thin-film transistor TFT, storage capacitor Cs, and pixel electrode Ep are set to each pixel  2 . Either of the source and drain of the pixel thin-film transistor TFT is connected to the data lines D and the other of them is connected to one-hand electrode of the storage capacitor Cs and the pixel electrode Ep, the gate of the transistor TFT is connected to the gate lines G. Moreover, the ground potential is applied to the other-hand electrode of the storage capacitor Cs. Furthermore, a common electrode Eo is set to a position corresponding to each pixel on the opposite-side glass substrate and a pixel capacitor Clc is formed between the pixel electrode Ep and the common electrode Eo. In this invention, the other-hand electrode of the storage capacitor is applied the ground potential, however, the other-hand electrode of the storage capacitor is applied some potential other than the ground potential.  
      Furthermore, data driver circuitry  3  for driving the data lines D and gate driver circuitry  4  for driving the gate lines G are formed at the outside of a region in which a plurality of pixels  2  are formed on the TFT-side glass substrate. Data-line driving circuitry  5  and analog switches (ASWs) SW 1 - 1  to SW 3 - 3  (hereafter also generally referred to as ASWs) are set to the data driver circuitry  3 . Output terminals of the data-line driving circuitry  5  are connected to video signal lines V 1  to V 3 . The data-line driving circuitry  5  outputs video signals to the video signal lines V 1  to V 3 .  
      Moreover, a plurality of data lines, for example, three data lines D adjacent to each other form one block (group). For example, the data lines D 1  to D 3  belong to a first group, the data lines D 4  to D 6  belong to a second group, and the data lines D 7  to D 9  belong to a third group. Furthermore, the data-line driving circuitry  5  is provided with the total of three output terminals respectively assigned to each group of the above data lines and the three output terminals are connected to the video signal lines V 1  to V 3 .  
      Furthermore, each video signal line is connected to each data line D through an ASW. Specifically, the video signal line V 1  is connected to the data lines D 1  to D 3  through the switches SW 1 - 1  to SW 1 - 3 , the video signal line V 2  is connected to the data lines D 4  to D 6  through the switches SW 2 - 1  to SW 2 - 3 , and the video signal line V 3  is connected to the data lines D 7  to D 9  through the switches SW 3 - 1  to SW 3 - 3 .  
      When generally showing the above description, n data lines D (three lines for this embodiment) belong to each group in the case of the data-line driving circuitry  5  and the k-th (k is an integer of 1 to n) switch for switching whether to connect the k-th data line D in each group to a video signal line is set. The number of the k-th switches is the same as the number of groups and is, for example, 3. That is, when assuming the number of groups as m, the number of output terminals, the number of video signal lines, and the number of k-th switches are respectively m and the total number of switches is the same as the number of data lines D, for example, 9.  
      Moreover, the total of n k-th control lines connected to the k-th switch in each group in common is set to the data-line driving circuitry  5 . For example, in the case of this embodiment, three control lines SP 1  to SP 3  are set. Furthermore, the control line SP 1  is connected to the switches SW 1 - 1 , SW 2 - 1 , and SW 3 - 1 , the control line SP 2  is connected to the switches SW 1 - 2 , SW 2 - 2 , and SW 3 - 2 , and the control line SP 3  is connected to the switches SW 1 - 3 , SW 2 - 3 , and SW 3 - 3 . Furthermore, driving circuitry  6  is set to the data-line driving circuitry  5  and the control lines SP 1  to SP 3  are connected to output terminals of the driving circuitry  6 .  
      The switches SW 1 - 1  to SW 3 - 3  are respectively constituted of, for example, a thin-film transistor (TFT), the data-line driving circuitry  5  is connected to one of the source and drain of each TFT, the data lines D are connected to the other of them, and the control lines SP 1  to SP 3  are connected to the gate of the transistor. Thereby, for example, when the potential of the control line SP 1  becomes high level, the switches SW 1 - 1 , SW 2 - 1 , and SW 3 - 1  are turned on and the video signal line V 1 , V 2  and V 3  are respectively connected to the data lines D 1 , D 4  and D 7 . When the potential of the control line SP 1  becomes low level, the switches SW 1 - 1 , SW 2 - 1 , and SW 3 - 1  are turned off and the data lines D 1 ,D 4  and D 7  respectively become a floating state.  
      This embodiment shows an example in which the number of data lines is 9, the number of gate lines is 6, and three adjacent data lines belong to one group and are connected to one output terminal of the data-line driving circuitry  5  via a ASW. However, the present invention is not restricted to the above example. The number of data lines, the number of gate lines, and the number of data lines belonging to one group do not influence the essence of the present invention.  
      Then, operations of the liquid-crystal display of this embodiment constituted as described above, that is, a driving method of the liquid-crystal display of this embodiment are described below. FIGS.  2  to  4  are timing charts showing operations of the liquid-crystal display of this embodiment by allocating time to the axis of abscissa and potential of each wiring to the axis of ordinate, in which  FIG. 2  shows operations in a certain vertical period,  FIG. 3  shows operations in a vertical period next to the vertical period shown in  FIG. 2 , and  FIG. 4  shows operations in a vertical period next to the vertical period shown in  FIG. 3 .  
      In the case of this embodiment, the gate driver circuitry  4  successively selects all gate lines G and the data driver circuitry  3  outputs video signals to all data lines D and thereby, a vertical period for displaying images for one screen on a screen constituted of a plurality of pixels  2  is repeatedly executed. Moreover, in each vertical period, a horizontal period for outputting video signals for one pixel row to the data lines D while one gate line G is selected is successively executed for all gate lines G.  
      The period TH shown in  FIG. 2  shows one horizontal period in which one gate line G 1  is selected by the gate driver circuitry  4  and video signals are written in one pixel row connected to the one gate line G 1 . Moreover, in periods TB 1  to TB 3  obtained by dividing the one horizontal period into three equal periods, the driving circuitry  6  sets the potential of any one of the control lines SP 1  to SP 3  for controlling ASWs to a potential for turning on an ASW, for example, a high-level potential. Namely, pulses are applied to the control lines SP 1  to SP 3 . In the vertical period shown in  FIG. 2 , pulses are applied to the control line SP 1  in the period TB 1 , pulses are applied to the control line SP 2  in the period TB 2 , and pulses are applied to the control line SP 3  in the period TB 3 . Thereby, the switches SW 1 - 1 , SW 2 - 1 , and SW 3 - 1  are turned on in the period TB 1  and the data lines D 1 , D 4 , and D 7  are connected to the video signal lines V 1 , V 2 , and V 3 . Moreover, in the period TB 2 , the switches SW 1 - 2 , SW 2 - 2 , and SW 3 - 2  are turned on and the data lines D 2 , D 5 , and D 8  are connected to the video signal lines V 1 , V 2 , and V 3 . Furthermore, in the period TB 3 , the switches SW 1 - 3 , SW 2 - 3 , and SW 3 - 3  are turned on and the data lines D 3 , D 6 , and D 9  are connected to the video signal lines V 1 , V 2 , and V 3 . In this embodiment, one horizontal period is divided into three equal periods, however, three divided periods do not need to be equal.  
      The data-line driving circuitry  5  outputs signals to be written in the pixel at the intersection between the data line D 1  and the gate line G 1  (hereafter referred to as pixels (D 1  and G 1 )) to the video signal line V 1  in the period TB 1  and outputs signals to be written in the pixel (D 4  and G 1 ) to the video signal line V 2  and signals to be written in the pixel (D 7  and G 1 ) to the video signal line V 3 . Similarly in the period TB 2 , the circuitry  5  outputs signals to be written in the pixels (D 2  and G 1 ), pixels (D 5  and G 1 ), and pixels (D 8  and G 1 ) to the video signal lines V 1 , V 2 , and V 3 . In the period TB 3 , the circuitry  5  outputs signals to be written in the pixels (D 3  and G 1 ), pixels (D 6  and G 1 ), and pixels (D 9  and G 1 ) to the video signal lines V 1 , V 2 , and V 3 .  
      In this case, because pulses at a voltage for turning on a pixel TFT are applied to the gate line G 1  in this horizontal period, a video signal voltage held by a data line is written in each pixel connected to the gate line G 1 . That is, a pixel thin-film transistor TFT connected to the gate line G 1  is turned on and the data lines D are connected to the pixel electrode Ep and one electrode of the storage capacitor Cs through the pixel thin-film transistor TFT and charges corresponding to video signals are accumulated in the pixel capacitor Clc and storage capacitor Cs, the liquid-crystal layer between the pixel electrode Ep and the common electrode Eo is oriented to form a part of an image. Moreover, by applying operations in the above horizontal period to all gate lines, it is possible to write video signals for one screen in all pixels  2  and display one screen by the whole screen.  
      Then, as shown in  FIG. 3 , in a vertical period continued from the vertical period shown in  FIG. 2 , pulses are applied to the control line SP 2  in the period TB 1 , the switches SW 1 - 2 , SW 2 - 2 , and SW 3 - 2  are turned on, video signals are written in the data lines D 2 , D 5 , and D 8 . Pulses are applied to the control line SP 3  in the period TB 2 , the switches SW 1 - 3 , SW 2 - 3  and SW 3 - 3  are turned on, video signals are written in the data lines D 3 , D 6  and D 9 . Pulses are applied to the control line SP 1  in the period TB 3 , the switches SW 1 - 1 , SW 2 - 1 , and SW 3 - 1  are turned on, and video signals are written in the data lines D 1 , D 4 , and D 7 .  
      Then, as shown in  FIG. 4 , in a vertical period continued from the vertical period shown in  FIG. 3 , pulses are applied to the control line SP 3  in the period TB 1 , the video signals are written in the data lines D 3 , D 6  and D 9 , pulses are applied to the control line SP 1  in the period TB 2 , video signals are written in the data lines D 1 , D 4 , and D 7 , pulses are applied to the control line SP 2  in the period TB 3 , and video signals are written in the data lines D 2 , D 5 , and D 8 .  
      In the vertical periods shown in  FIGS. 3 and 4 , the sequence for writing a video signal in a data line in one horizontal period is only different from the case of the vertical period in  FIG. 2  but operations other than that is the same as the operations in the vertical period in  FIG. 2  and video signals for one screen are displayed. An operation is realized in which an order that data-line driving circuitry writes data in each data line in time division is changed for every three continuous vertical periods in accordance with the above operation. That is, there are three types of sequences each of which outputs a video signal to a data line and the three types of sequences are repeatedly executed for every cycle constituted of three continuous vertical periods.  
      Then, advantages of this embodiment are described below. According to this embodiment, it is possible to greatly decrease the number of streak-like luminance irregularities along a data line. The reason is described below. As described above, in the case of the driving method for successively writing a signal in a data line in time division, streak-like irregularity is caused because the fluctuation of a potential generated through a parasitic capacitance when writing a signal in other data line differs between data lines by depending on a sequence for writing a signal. However, according to this embodiment, because a sequence for writing a signal in a data line in one horizontal period for every vertical period is changed, it is possible to prevent a large potential fluctuation from always occurring in the same data line and decrease the number of streak-like irregularities.  
      Moreover, because a cycle in which the sequence is changed makes circuitry in three vertical periods equal to the number of data lines to be driven by one output of data-line driving circuitry and thereby, the potential fluctuation of a data line is uniformed in each data line, a luminance difference generated as a result is uniformed and it is not recognized as streak-like irregularity.  
      Then, second embodiment of the present invention is described. FIGS.  5  to  7  are timing charts showing operations of a liquid-crystal display of this embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate, in which  FIG. 5  shows operations in a plurality of continuous horizontal periods in a certain vertical period,  FIG. 6  shows operations in a plurality of continuous horizontal periods in a vertical period next to the vertical period shown in  FIG. 5 , and  FIG. 7  shows operations in a plurality of continuous horizontal periods in a vertical period next to the vertical period shown in  FIG. 6 . A configuration of the liquid-crystal display of this embodiment is the same as that of the above-described first embodiment but only a signal generation sequence of driving circuitry  6  is different from the case of the above-described first embodiment.  
      The periods TH 3   k , TH 3   k+ 1   , TH 3   k+ 2, and TH 3 ( k+ 1) shown in  FIG. 5  respectively show a horizontal period and each horizontal period is divided into three periods TB 1 , TB 2 , and TB 3  which are almost divided into three equal periods. In the period TB 1  of the horizontal period TH 3   k , pulses at a potential at which an ASW is turned on are applied to a control line SP 1  to write video signals in data lines D 1 , D 4 , and D 7 . Moreover, in the period TB 2 , pulses are applied to a control line SP 2  to write video signals in data lines D 2 , D 5 , and D 8 . Furthermore, in the period TB 3 , pulses are applied to a control line SP 3  to write video signals in data lines D 3 , D 6 , and D 9 . In the next horizontal period TH 3   k+ 1, the video signals are written in the data lines D 2 , D 5  and D 8  in the period TB 1 , the video signals are written in the data lines D 3 , D 6  and D 9  in the period TB 2  and the video signal are written in the data lines D 1 , D 4  and D 7  in the period TB 3 . Thus, in the vertical period shown in  FIG. 5 , a sequence for writing a signal in a data line is differentiated for every horizontal period.  
      Then, in the case of the vertical period shown in  FIG. 6 , video signals are written in the data lines D 2 , D 5 , and D 8  in the period TB 1 , video signals are written in the data lines D 3 , D 6 , and D 9  in the period TB 2 , and video signal are written in the data lines D 1 , D 4 , and D 7  in the period TB 3  in the horizontal period TH 3   k . Then, data lines in which signals will be written for every three divided periods are changed also in the periods T 3   k+ 1 and T 3   k+ 2. Moreover, in the vertical period shown in  FIG. 7  continued from the above vertical period, video signals are written in the data lines D 3 , D 6 , and D 9  in the period TB 1 , video signals are written in the data lines D 1 , D 4 , and D 7  in the period TB 2 , and video signals are written in the data lines D 2 , D 5 , and D 8  in the period TB 3  in the horizontal period T 3   k . Then, also in the continued horizontal periods T 3   k+ 1 and T 3   k+ 2, data lines in which signals are written for every three divided periods are changed. That is, in the case of this operation, a sequence for writing a signal in a data line is changed for every three continued horizontal periods and the sequence is counterchanged in three continuous vertical periods.  
      In the case of this embodiment, by performing the above operations, a sequence for writing a signal in a data line is changed for every continuous vertical period and it is also changed for every horizontal period in the same vertical period. Thereby, because a data line which receives much potential fluctuation due to a parasitic capacitance with an adjacent data line is changed at a cycle in which a horizontal period is repeated, a person cannot easily recognize a luminance difference between pixels due to potential fluctuation. As a result, it is possible to make it more difficult that streak-like irregularity is recognized compared with the case of the above first embodiment.  
      In the case of this embodiment, a sequence for writing a signal in a data line is changed for every continuous vertical period. However, it doesn&#39;t require to change for every continuous vertical period, if the sequence is changed for every horizontal period in the same vertical period.  
      Then, third embodiment of the present invention is described below.  FIG. 8  is a block diagram showing a liquid-crystal display of this embodiment. As shown in  FIG. 8 , in the case of the liquid-crystal display  1   a  of this embodiment, signal processing circuitry  7  is set to the liquid-crystal display  1  of the above first embodiment. The signal processing circuitry  7  generates a video signal and a control signal to be supplied to the liquid-crystal display  1  from a video signal and a sync signal input from the outside and supplies these signals to the liquid-crystal display  1  together with a power-supply voltage. The signal processing circuitry  7  is provided with a memory  8  capable of holding video signals to be displayed on the liquid-crystal display  1  for at least one screen or preferably for two screens.  
      Then, operations of the liquid-crystal display of this embodiment constituted as described above, that is, a driving method of the liquid-crystal display of this embodiment are described below.  FIG. 9  is a timing chart showing operations of the liquid-crystal display of this embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate. In  FIG. 9 , signals VSYNC_IN and VIDEO_IN show a vertical sync signal of a video signal and a video signal supplied to the signal processing circuitry  7  from a signal source and signals VSYNC and VIDEO show a vertical sync signal and video signal supplied to the liquid-crystal display  1 .  
      Video signals for one screen are supplied to the signal processing circuitry  7  for every vertical period TVin and the memory  8  temporarily stores the video signals. Then, the signal processing circuitry  7  compresses the time width of the video signals for one screen stored in the memory  8  to, for example, (⅓) times. Then, the signal processing circuitry  7  outputs the compressed video signals to the liquid-crystal display  1  at a frequency three times higher than a frequency supplied from a signal source. Then, the liquid-crystal display  1  displays an image by the operation same as the case of the above-described first embodiment in accordance with a video signal input at the three-time-high frequency. Therefore, the vertical period TV of a video signal to be supplied to the liquid-crystal display  1  has a length ⅓ the vertical period TVin of a video signal to be supplied to the signal processing circuitry  7 .  
      Thus, this embodiment displays the same video signal a plurality of times in one vertical period of a video signal supplied from a signal source. Moreover, it is preferable that the number of times for displaying the same video signal is equal to the number of data lines (three lines for this embodiment) to be driven by one output of the data driving circuitry in the liquid-crystal display in time division.  
      Then, advantages of this embodiment are described below. In the case of this embodiment, it is possible to further shorten a cycle for changing a writing sequence in a data line compared with the above described first and second embodiment. Thereby, it is possible to make it more difficult that streak-like irregularity is recognized. As a result, it is possible to almost completely prevent streak-like irregularity from being recognized.  
      Moreover, by equalizing the number of times for displaying the same video signal in one vertical period of an external signal with the number of data lines to be connected to one output terminal of data driving circuitry, that is, the number of data lines belonging to one group, it is possible to almost equalize potential fluctuations generated in all data lines in one vertical period of a video signal input to the signal processing circuitry  7  from a signal source. Therefore, it is possible to make it more difficult that the luminance difference between pixels due to potential fluctuation is recognized.  
      In the case of this embodiment, an example is shown in which a video signal supplied to the signal processing circuitry  7  from a signal source is an analog signal and a video signal supplied to the liquid-crystal display  1  from the signal processing circuitry  7  is also an analog signal. Even if these video signals are received as digital signals, there is no problem. Moreover, in this embodiment, though an example is shown in which operations of the liquid-crystal display  1  are the same as the case of the above-described first embodiment, it is allowed to make the operations same as the case of the above-described second embodiment.  
      Then, fourth embodiment of the present invention is described.  FIG. 10  is a block diagram showing a liquid-crystal display of this embodiment.  FIG. 11  is circuitry diagram showing gate driver circuitry of this embodiment,  FIG. 12  is a block diagram showing a data-line driving circuitry of this embodiment, and  FIG. 13  is sectional view showing the liquid-crystal display of this embodiment. The fourth embodiment describes the above-described first embodiment more minutely.  
      As shown in  FIG. 10 , in the case of the liquid-crystal display of this embodiment, a connection terminal  9  for inputting a signal from the outside is set on a TFT-side glass substrate  12  (refer to  FIG. 13 ). Data driver circuitry  3 , gate driver circuitry  4 , and common electrode set on an opposite-side glass substrate  13  (refer to  FIG. 13 ) are connected to the connection terminal  9 . Moreover, signals to be supplied to the data-line driving circuitry  5  and driving circuitry  6  of the data driver circuitry  3 , gate driver circuitry  4 , and common electrode are supplied from the outside through the connection terminal  9 . In general, an Flexible Printed Circuitry (FPC) is used for the above connection.  
      As shown in  FIG. 11 , the gate driver circuitry  4  is constituted of buffer circuitry using inverter and a static shift register constituted of a CMOS. That is, in the case of the gate driver circuitry  4 , a plurality of circuit blocks  10  are connected at a plurality of stages in series. Moreover, a start signal GST is input to the first-stage circuitry block  10  and an output signal of the previous-stage circuitry block is input to circuit blocks  10  downward from the second-stage circuit block  10 . In  FIG. 11 , only the first- and second-stage circuit blocks  10  are illustrated.  
      A clocked inverter CIV 1  to which the start signal GST or an output signal of the circuit block  10  at the previous stage is input is set to the input node of the circuit block  10  at each stage. Moreover, an inverter IV 1  whose input node is connected to the output node of the clocked inverter CIV 1  is set and a clocked inverter IV 2  whose input node is connected to the output node of the inverter IV 1  and whose output node is connected to the input node of the inverter IV 1  is set. Furthermore, a clocked inverter CIV 3  whose input node is connected to the output node of the inverter IV 1  is set, an inverter IV 2  whose input node is connected to the output node of the clocked inverter CIV 3  is set and a clocked inverter IV 4  whose input node is connected to the output node of the inverter IV 2  and whose output node is connected to the input node of the inverter IV 2  is set. Furthermore, the output node of the inverter IV 2  serves as the output node of the circuit block  10  and connected to the input node of the clocked inverter CIV 1  of the circuit block  10  at the next stage. Furthermore, inverters IV 3  to IV 6  are connected in order in series, the input node of the inverter IV 3  is connected to the output node of the inverter IV 2  and the output node of the inverter IV 6  is connected to a gate line G. That is, the output node of the inverter IV 6  of the circuit block  10  at the first stage is connected to the gate line G 1  and the output node of the inverter IV 6  of the circuit block  10  at the k-th stage is connected to the gate line Gk. A clocked inverter is controlled by two clock signals GCLK and /GCLK whose phases are different from each other.  
      The data-line driving circuitry  5  samples a video signal supplied from the outside and digital-analog-converts and outputs the video signal. Moreover, the circuitry  5  selects and outputs any one of signals held in the inside. The data-line driving circuitry  5  is COG-connected onto the TFT-side glass substrate  12  (refer to  FIG. 13 ). In this case, what number of data lines is driven by one output of the data-line driving circuitry  5  is frequently decided by a terminal pitch and a pixel pitch when performing COG connection. At present, the minimum terminal pitch of COG connection is approx. 60 μm and the resolution of a liquid-crystal display used for a projector is a length of 1024 and width of 768. Therefore, When a display diagonal is 1″ (approx. 25.4 mm), the pixel pitch becomes approx. 20 μm. Therefore, when one output of data-line driving circuitry drives three data lines, it is possible to decrease a region of a wiring connecting the data-line driving circuitry with a data line and this is advantageous in downsizing a liquid-crystal display.  
      As shown in  FIG. 12 , the data-line driving circuitry is provided with a shift register  11 . A start signal DSTP and clock signal DCLK are input to the shift register  11  and the circuitry  5  successively outputs signals from nine output terminals DSR 1  to DSR 9 . Moreover, data sampling switches DSP 1  to DSP 9  in which turning-on/turning-off is selected by signals output from output terminals DSR 1  to DSR 9  are set to the data-line driving circuitry  5  and a video signal VIDEO is applied to one ends of the data sampling switches DSP 1  to DSP 9  from the outside through the connection terminal  9  (refer to  FIG. 10 ).  
      Moreover, memories MI 11  to M 19  are connected to the other ends of the data sampling switches DSP 1  to DSP 9 . The memories M 11  to M 19  constitute a first memory group. The first memory group samples a video signal supplied from the outside in accordance with an output of the shift register  11 . Moreover, data transfer switches DTR 1  to DTR 9  are connected to the memories M 11  to M 19 . These data transfer switches DTR 1  to DTR 9  select turning-on/turning-off by a common control signal TR. The data transfer switches DTR 1  to DTR 9  simultaneously transfer signals held by the first memory group.  
      Furthermore, memories M 21  to M 29  are connected to the other ends of the data transfer switches DTR 1  to DTR 9 . The memories M 21  to M 29  constitute a second memory group. The second memory group holds video signals transferred from the first memory group. The memories M 21  to M 29  are connected to one ends of data selection switches DSL 1  to DSL 9 . The other ends of the data selection switches DSL 1  to DSL 3  are connected to DAC circuitry DAC 1  for digital-analog-converting the contents of the second memory, the other ends of the data selection switches DSL 4  to DSL 6  are connected to DAC circuitry DAC 2 , and the other ends of the data selection switches DSL 7  to DSL 9  are connected to DAC circuitry DAC 3 .  
      Furthermore, turning-on/turning-off of the data selection switches DSL 1 , DSL 4 , and DSL 7  is selected by a common control signal SL 1 , turning-on/turning-off of the data selection switches DSL 2 , DSL 5 , and DSL 8  is selected by a common control signal SL 2 , and turning-on/turning-off of the data selection switches DSL 3 , DSL 6 , and DSL 9  is selected by a common control signal SL 3 .  
      Furthermore, amplifiers AMP 1  to AMP 3  for amplifying an output of DAC circuitry are set to the data-line driving circuitry  5  and input terminals of the amplifiers AMP 1  to AMP 3  are connected to the DAC circuitry DAC 1  to DAC 3 , and output terminals of the amplifiers AMP 1  to AMP 3  are connected to video signal lines V 1  to V 3 .  
      As shown in  FIG. 13 , the liquid-crystal display  1  of this embodiment is provided with a TFT-side glass substrate  12  and an opposite-side glass substrate  13  which are arranged in parallel to each other. Moreover, a liquid-crystal layer  14  is formed between the TFT-side glass substrate  12  and the opposite-side glass substrate  13 .  
      A lower light-shielding film  15  made of WSi is formed on a part of the TFT-side glass substrate  12  and an interlayer film  16  made of SiO 2  is formed on the entire surface of the TFT-side glass substrate  12  so as to embed the lower light-shielding film  15 . A semiconductor layer  17  made of P—Si (polysilicon) doped with an impurity is formed on a part of the interlayer film  16 . The semiconductor layer  17  serves as the source region, channel region, and drain region of a TFT and one-hand electrode of the storage capacitor Cs. Moreover, a gate insulating film  18  made of SiO 2  is formed on the entire surface of the interlayer film  16  so as to embed the semiconductor layer  17 . A gate metallic film  19  made of WSi is formed on a part of a region immediately above the semiconductor layer  17  on the gate insulating film  18 . A region immediately below the gate metallic film  19  on the semiconductor layer  17  serves as the channel region of a TFT and regions at the both sides of the film  19  serve as a source and drain regions. Moreover, the gate metallic film  19  is connected to the gate lines G (refer to  FIG. 10 ). Moreover, a capacitor metallic film  20  made of WSi is formed on the same layer as the gate metallic film  19 . The capacitor metallic film  20  serves as the other-hand electrode of the storage capacitor Cs.  
      Then, an interlayer film  21  made of SiN is formed on the entire surface of the gate insulating film  18  so as to embed the gate metallic film  19  and capacitor metallic film  20  and first-layer metallic wiring films  22   a  to  22   d  made of Al are formed on a part of the interlayer film  21 . The metallic wiring film  22   a  is connected to the lower light-shielding film  15  through a via  23   a  penetrating the interlayer film  21 , gate insulating film  18 , and interlayer film  16 . Moreover, the metallic wiring film  22   a  is connected to a predetermined potential wiring (not illustrated). The metallic wiring film  22   b  is connected to either of the source and drain regions of the semiconductor layer  17  through a via  23   b  penetrating the interlayer film  21  and gate insulating film  18 . Furthermore, the metallic wiring film  22   b  is connected to data lines D (refer to  FIG. 10 ). The metallic wiring film  22   c  is connected to the other of the source and drain regions of the semiconductor layer  17  through a via  23   c  penetrating the interlayer film  21  and gate insulating film  18 . The metallic wiring film  22  disconnected to the capacitor metallic film  20  through a via  23   d  penetrating the interlayer film  21 .  
      Moreover, an interlayer film  24  made of SiN is formed on the entire surface of the interlayer film  21  so as to embed the first-layer metallic wiring films  22   a  to  22   d  and an upper light-shielding film  25  made of Al is formed on a part of the inter layer film  24 . Furthermore, a second-layer metallic wiring film  26  made of Al is formed on the same layer as the upper light-shielding film  25 . The metallic wiring film  26  is connected to the metallic wiring film  22   d  through a via  27  penetrating the interlayer film  24 . Furthermore, the metallic wiring film  26  is also connected to a ground potential wiring (not illustrated). An interlayer film  28  made of SiN is formed on the entire surface of the interlayer film  24  so as to embed the upper light-shielding film  25  and metallic wiring film  26 .  
      Furthermore, a transparent pixel electrode Ep made of ITO (Indium tin oxide) is formed on a part of the interlayer film  28 . The pixel electrode Ep is connected to the metallic wiring film  22   c  through a through-hole  29  formed on the interlayer films  28  and  26 . Furthermore, an alignment film  30  is formed on the entire surfaces of the interlayer film  28  and pixel electrode Ep.  
      A common electrode Eo made of ITO is formed on the opposite-side glass substrate  13  and an alignment film  31  is formed on the common electrode Eo. Moreover, the liquid-crystal layer  14  is formed so as to contact with the alignment films  30  and  31 . Configurations of this embodiment other than the above described are the same as those of the above-described first embodiment.  
      Then, operations of the liquid-crystal display of this embodiment constituted as described above, that is, a driving method of the liquid-crystal display of this embodiment are described below.  FIG. 14  is a timing chart showing operations of gate driver circuitry of the liquid-crystal display of this embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate. FIGS.  15  to  17  are timing charts respectively showing operations of data driver circuitry of the liquid-crystal display of this embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate, in which  FIG. 15  shows the operation in a certain vertical period,  FIG. 16  shows the operation in a vertical period next to the vertical period in  FIG. 15 , and  FIG. 17  shows the operation in a vertical period next to the vertical period in  FIG. 16 .  
      As shown in  FIG. 14 , the gate driver circuitry  4  is controlled by a start signal GST and two clock signals GCLK and /GCLK whose phases are different from each other. When the start signal GST synchronizing with a clock signal is supplied to the first-stage circuitry block  10  (refer to FIG.  11 ) of the gate driver circuitry  4 , the gate driver circuitry  4  successively outputs a pulse having a length of one cycle of a clock synchronously with a clock signal. In this case, when equalizing the cycle of the clock signal GCLK with the cycle of the horizontal period of the liquid-crystal display, the gate driver circuitry  4  performs an operation for successively outputting a pulse to gate lines G for every horizontal period. That is, the start signal GST becomes high-level at the beginning of the vertical period TV shown in  FIG. 14  and the gate lines G successively become high-level by using the fact that the start signal GST becomes high-level as a trigger. A period in which one gate line G is kept high-level is the horizontal period TH.  
      Moreover, as shown in  FIG. 15 , a start signal DSTP becomes high-level at the beginning of each horizontal period in an certain vertical period. Furthermore, the video signal VIDEO for displaying an image in the liquid-cristal display is successively supplied to the shift register  11  of the data driver circuitry  5  from the outside synchronously with the clock signal DCLK by using the start signal DSTP as a trigger. Then, the shift register  11  successively outputs pulses to the output terminals DSR 1  to DSR 9  synchronously with the clock signal DCLK and successively turns on the data sampling switches DSP 1  to DSP 9 . Thereby, the first memory group (memories M 11  to M 19 ) successively samples and holds the supplied video signal VIDEO. After all signals are held by the first memory group, the data transfer switches DTR 1  to DTR 9  are simultaneously turned on by the control signal TR, signals held by the first memory group are simultaneously transferred to the second memory group (memories M 21  to M 29 ), and the second memory group holds the signals.  
      In the case of the held video signals, when the control signals SL 1  to SL 3  successively become high-level in the next horizontal period, the data selection switches DSL 1 , DSL 4 , and DSL 7  are turned on in the period TB 1 , the data selection switches DSL 2 , DSL 5 , and DSL 8  are turned on in the period TB 2 , and the data selection switches DSL 3 , DSL 6 , and DSL 9  are turned on in the period TB 3 . Thereby, video signals held by the memories M 21 , M 24 , and M 27  are output to the DAC circuitry DAC 1  to DAC 3  in the period TB 1 , digital-analog-converted by the DAC circuitry, amplified by the amplifiers AMP 1  to AMP 3 , and output to the video signal lines V 1  to V 3 . In this case, the signals output to the video signal lines V 1  to V 3  are written in the data lines D 1 , D 4 , and D 7  in order to set the signal SP 1  for the driving circuitry  6  (refer to  FIG. 10 ) to control ASWs to a potential (high level) for turning on ASWs.  
      Similarly, video signals held by the memories M 22 , M 25 , and M 28  are analog-converted, amplified, and output to the video signal lines V 1  to V 3  in the period TB 2 . Then, because the signal SP 2  becomes high-level, the signals output to the video signal lines V 1  to V 3  are written in the data lines D 2 , D 5 , and D 8 . Moreover, in the period TB 3 , the video signals held by the memories M 23 , M 26 , and M 29  are analog-converted, amplified, and output to the video signal lines V 1  to V 3 . When the signal SP 3  becomes high-level, the video signals are written in the data lines D 3 , D 6 , and D 9 .  
      As described above, because the gate driver circuitry  4  outputs a pulse for turning on a pixel thin-film transistor TFT to one gate line for every horizontal period, the signal written in data lines D are written in the pixel capacitor Clc and storage capacitor Cs. By applying this operation to all pixel rows, it is possible to display a two-dimensional image.  
      Moreover, as shown in  FIG. 16 , video signals are first written in the data lines D 2 , D 5 , and D 8  in the period TB 1  in one horizontal period in a vertical period next to the vertical period shown in  FIG. 15  and then, video signals are written in the data lines D 3 , D 6 , and D 9  in the period TB 2 , and finally signals are written in the data lines D 1 , D 4 , and D 7  in the period TB 3 .  
      Furthermore, as shown in  FIG. 17 , in a vertical period next to the vertical period shown in  FIG. 16 , video signals are first written in the data lines D 3 , D 6 , and D 9  in the period TB 1  in one horizontal period, then video signals are written in the data lines D 1 , D 4 , and D 7  in the period TB 2 , and finally video signals are written in the data lines D 2 , D 5 , and D 8  in the period TB 3 .  
      The following advantage can be obtained from the liquid-crystal display of this embodiment. That is to greatly decrease the number of streak-like luminance irregularities along data lines. The reason is described below. Streak-like luminance irregularity is generated because a potential generated through a parasitic capacitance is different between data lines by depending on a sequence for writing a signal when writing a signal in another data line in driving for successively writing signals in data lines in time division in one horizontal period. However, in the case of the driving method of the liquid-crystal display of this embodiment, because a sequence for writing a signal in a data line in one horizontal period for every vertical period is changed. Therefore, a large potential fluctuation does not always occur in the same data line. Moreover, the cycle for the sequence to change makes circuitry in three vertical periods equal to the number of data lines to be driven by one output of data-line driving circuitry. Therefore, because potential fluctuations of data lines are uniformed in each data line, luminance differences generated as a result are also averaged and are not easily recognized as streak-like irregularity.  
      In the case of this embodiment, an example is shown in which each stage of the shift register in the gate driver circuitry  4  is constituted of four clocked inverters and two inverters. However, the present invention is not restricted to the above example. Even if a configuration other than the above is used, there is no problem as long as circuitry for successively outputting an output synchronously with a clock signal is used.  
      Furthermore, in the case of this embodiment, an example is shown in which the data driver circuitry  5  is constituted of the first memory group (memories M 11  to M 19 ), second memory group (memories M 21  to M 29 ), DAC circuitry DAC 1  to DAC 3  for digital-analog-converting the contents of the second memory group, amplifiers AMP 1  to AMP 3  for amplifying outputs of the DAC circuitry, and data selection switches DSL 1  to DSL 9  for connecting the second memory group with the DAC circuitry. However, the present invention is not restricted to the above example. Even if using a configuration other than the above, there is no problem as long as circuitry having the above function is used.  
      Furthermore, in the case of the liquid-crystal display of this embodiment, materials for forming a wiring metallic film, light-shielding metallic film, and interlayer film are not greatly related with the essence of the present invention. There is no problem even if using materials other than the above materials.  
      Furthermore, in the case of this embodiment, an example is shown in which the number of data lines is 9, the number of gate lines is 6, and the number of data lines connected to one output of data-line driving circuitry is 3. However, the present invention is not restricted to the above example. It is possible to optionally select these values in accordance with the specification of a required liquid-crystal display.  
      Furthermore, in the case of this embodiment, an example is shown in which gate driver circuitry is constituted by forming a pixel TFT on a TFT-side glass substrate on which pixels are arranged. However, it is also allowed to supply a signal for driving each gate line from the outside. However, it is preferable to fabricate a liquid-crystal display for a projector on the same substrate as pixels because it is necessary to minimize the size of the display.  
      Furthermore, in the case of this embodiment, an example is shown in which gate driver circuitry is set to only either side of a pixel matrix. However, it is also allowed to set the gate driver circuitry to the both sides of the pixel matrix. In this case, by driving one gate line from two directions by two gate driver circuitry arranged at the both sides, an advantage is obtained that the rise time and fall time of a pulse to be supplied to a gate line are shortened. Moreover, by driving different gate lines by the two gate driver circuitry arrange at the both sides, this is advantageous for decreasing a liquid-crystal display in size and improving the display in definition because it is possible to take a large pitch between output terminals in each gate driver circuitry.  
      Furthermore, it is also allowed to supply a signal and power-supply voltage necessary for the gate driver circuitry  4  and a power-supply voltage to be supplied to a common electrode from the data-line driving circuitry  5 .  
      Then, fifth embodiment of the present invention is described below. This embodiment is described more minutely than the embodiment transformed the above-described second embodiment. Because a configuration of the liquid-crystal display of this embodiment is the same as the configuration of the liquid-crystal display of the above-described fourth embodiment, its description is omitted. Operations of the liquid-crystal display of this embodiment are described below.  FIG. 18  is a timing chart showing operations of data driver circuitry of the liquid-crystal display of this embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate. As shown in  FIG. 18 , when the driving circuitry  6  (refer to  FIG. 10 ) sets the potential of the control line SP 1  to high level in the period TB 1  in a certain horizontal period TH 3   k , video signals are written in the data lines D 1 , D 4 , and D 7 . Then, the potential of the control line SP 2  becomes high-level in the period TB 2  and video signals are written in the data lines D 2 , D 5 , and D 8 . Then, in the period TB 3 , the potential of the control line SP 3  becomes high-level and video signals are written in the data lines D 3 , D 6 , and D 7 . Operations until a signal is written in data-line driving circuitry in a horizontal period and output are the same as the operations described for the above fourth embodiment.  
      In TH 3   k+ 1 which is the next horizontal period, video signals are written in the data lines D 2 , D 5 , and D 8  in the period TB 1 , then video signals are written in the data lines D 3 , D 6 , and D 9  in the period TB 2 , and video signals are written in the data lines D 1 , D 4 , and D 7  in the period TB 3 . In the next horizontal period TH 3   k+ 2, video signals are written in the data lines D 3 , D 6 , and D 9  in the period TB 1 , video signals are written in the data lines D 1 , D 4 , and D 7  in the period TB 2 , and signals are written in the data lines D 2 , D 5 , and D 8  in the period TB 3 . Thus, in the case of this embodiment, a sequence for writing a video signal in a data line is differentiated for every horizontal period.  
      In the case of the liquid-crystal display of this embodiment, the following advantage is obtained. It is an advantage that recognition of streak-like irregularity is made difficult. The reason why this advantage is obtained is that a data line for receiving much potential fluctuation of a data line is changed by the frequency in a horizontal period because a sequence for writing the signals in the data lines is changed for every continuous horizontal period and therefore, a person cannot easily recognize a luminance difference between pixels due to potential fluctuation.  
      Then, sixth embodiment of the present invention is described below. Because a configuration of the liquid-crystal display of this embodiment is the same as the configuration of the liquid-crystal display of the fourth embodiment, its description is omitted. Operations of the liquid-crystal display of this embodiment are described below. This embodiment is obtained by further improving the driving method of the liquid-crystal display of the fifth embodiment. In the case of the driving method of the liquid-crystal display of this embodiment, an operation in a certain vertical period is the same as the operation shown in  FIG. 18 . Moreover,  FIGS. 19 and 20  are timing charts respectively showing operations of data driver circuitry of the liquid-crystal display of this embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate, in which  FIG. 19  shows the operation in a vertical period next to the vertical period shown in  FIG. 18  and FIG.  20  shows the operation in a vertical period next to the vertical period in  FIG. 19 .  
      As shown in  FIG. 19 , the operation in the vertical period next to the vertical period shown in  FIG. 18  is described below. In a certain horizontal period TH 3   k , video signals are first written in the data lines D 2 , D 5 , and D 8 , then video signals are written in the data lines D 3 , D 6 , and D 9 , and finally video signals are written in the data lines D 1 , D 4 , and D 7 . In the next horizontal period TH 3   k+ 1, video signals are first written in the data lines D 3 , D 6 , and D 9 , then video signals are written in the data lines D 1 , D 4 , and D 7 , and finally video signals are written in the data-lines D 2 , D 5 , and D 8 . In the next horizontal period TH 3   k+ 2, video signals are first written in the data lines D 1 , D 4 , and D 7 , then video signals are written in the data lines D 2 , D 5 , and D 8 , and finally video signals are written in the data lines D 3 , D 6 , and D 9 .  
      As shown in  FIG. 20 , in the further next vertical period, in the horizontal period TH 3   k , video signals are first written in the data lines D 3 , D 6 , and D 9 , then video signals are written in the data lines D 1 , D 4 , and D 7 , and finally video signals are written in the data lines D 2 , D 5 , and D 8 . In the next horizontal period TH 3   k+ 1, video signals are first written in the data lines D 1 , D 4 , and D 7 , then video signals are written in the data lines D 2 , D 5 , and D 8 , and finally video signals are written in the data lines D 3 , D 6 , and D 9 . In the next horizontal period TH 3   k+ 2, video signals are first written in the data lines D 2 , D 5 , and D 8 , then video signals are written in the data lines D 3 , D 6 , and D 9 , and finally video signals are written in the data lines D 1 , D 4 , and D 7 . Operations other than the above of this embodiment are the same as those of the above-described fifth embodiment.  
      According to this embodiment, a sequence for writing a signal in a data line is differentiated for every vertical period and also differentiated for every horizontal period compared to the case of the above-described fourth and fifth embodiments. Therefore, it is possible to differentiate a data line which receives potential fluctuation for every vertical period and horizontal period. Thereby, it is more difficult for a person to recognize a luminance difference between pixels due to potential fluctuation and it is possible to more securely eliminate streak-like irregularity. Advantages other than the above mentioned of this embodiment are the same as those of the above-described fourth and fifth embodiments.  
      Then, seventh embodiment of the present invention is described.  FIG. 21  is a block diagram showing a liquid-crystal display of this embodiment. As shown in  FIG. 21 , the liquid-crystal display  1   a  of this embodiment is obtained by setting signal processing circuitry  7  to the liquid-crystal display  1  of the above-described fourth embodiment. The sixth embodiment describes the above-described third embodiment more minutely. A configuration of the liquid-crystal display  1  is described for the above-described fourth embodiment.  
      An input video signal and a sync signal are supplied to the signal processing circuitry  7  from a signal source (not illustrated) for supplying video signals and the circuitry  7  supplies the video signal and the control signal to the liquid-crystal display  1  and also supplies various power-supply voltages necessary for the liquid-crystal display  1 . The signal processing circuitry  7  is provided with a memory  32  capable of holding video signals supplied from the signal source for at least one screen. The memory  32  is provided with frame memories  33  and  34  respectively capable of holding video signals for one screen. Moreover, the memory  32  is provided with a switch  35  for selecting whether to input a video signal supplied from an external signal source to the frame memory  33  or  34  and a switch  36  for selecting whether to output a video signal stored in the frame memory  33  to the liquid-crystal display  1  or output a video signal stored in the frame memory  34  to the liquid-crystal display  1 .  
      Furthermore, the signal processing circuitry  7  is provided with a control circuitry  37  to which a sync signal is input from a signal source and which outputs a memory control signal MW for controlling the switch  35  and a memory control signal MR for controlling the switch  36  and outputs a control signal to the liquid-crystal display  1 . Furthermore, the signal processing circuitry  7  is provided with a power-supply circuitry  38  for generating various power-supply voltages and outputting the voltages to the liquid-crystal display  1 .  
      Then, operations of the liquid-crystal display of this embodiment constituted as described above, that is, a driving method of the liquid-crystal display of this embodiment are described below.  FIG. 22  is a timing chart showing operations of the signal processing circuitry of this embodiment by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate.  FIG. 23  is an illustration showing the polarity of a video signal to be applied to the pixel electrode of each pixel in a certain vertical period and  FIG. 24  is an illustration sowing the polarity of a video signal to be applied to the pixel electrode of each pixel in a vertical period next to the vertical period in  FIG. 23 .  
      As shown in  FIG. 22 , a video signal VIODEO_IN output from a signal source is input to the signal processing circuitry  7  by synchronizing with a sync signal VSYNC_IN similarly output from the signal source. The video signal VIDEO_IN is an analog signal and the sync signal VSYNC_IN is a digital signal which becomes high-level only at the beginning of each vertical period of the video signal VIDEO_IN. The memory control signals MW and MR are signals for deciding writing a signal in the frame memory  33  or  34  and reading a signal from the frame memory  33  or  34  by controlling the switch  35  and  36  respectively.  
      In a certain vertical period TVin (2m), it is assumed that the memory control signal MW is kept high-level, the memory control signal MR is kept low-level, and therefore, the video signal VIDEO_IN supplied from a signal source is written in the frame memory  33 , and the video signal VIDEO_IN is read from the frame memory  34 . Then, in a vertical period TVin (2 m+1) continued from the vertical period TVin (2m), levels of the memory control signals MW and MR are reversed, a signal is written in the frame memory  34 , and a signal is read from the frame memory  33 . By performing the operations, a frequency conversion of reading a video signal supplied from a signal source with another frequency is realized. In the case of the example shown in  FIG. 22 , a video signal input from a signal source and stored in a frame memory is read at triple frequency and the same signal is supplied to the liquid-crystal display  1  three times in one vertical period of a video signal supplied from a signal source. Thereby, it is possible to compress the time width of the video signal VIDEO_IN to (⅓) times and supply a video signal VIDEO having a frequency three times higher than the frequency of the video signal VIDEO_IN to the liquid-crystal display  1 .  
      Then, the liquid-crystal display  1  displays a video signal supplied from a signal source at triple speed for every three times. It is also allowed to apply any one of the methods of the above-described fourth to sixth embodiment to the operation of the liquid-crystal display  1  in this case. In this case, as shown in  FIGS. 23 and 24 , it is allowed that the liquid-crystal display  1  writes signals having the same polarity as a common electrode in all pixel electrodes in one vertical period for displaying video signals for one screen and perform the frame inversion for reversing the polarity for every vertical period. That is, it is allowed to write a signal having a positive polarity in a common electrode in the vertical period shown in  FIG. 23  and a signal having a negative polarity to the common electrode in a pixel electrode in the next vertical period shown in  FIG. 24 .  
      Then, advantages of this embodiment are described below. In the case of this embodiment, a vertical period is shortened compared to the above-described fourth to sixth embodiments. Therefore, a cycle for changing a sequence for writing a video signal in a data line is further shortened and recognition of streak-like irregularity becomes more difficult. Thereby, it is possible that recognition of streak-like irregularity is made almost completely impossible.  
      Moreover, because the number of times for displaying the same video signal in one vertical period of an external signal is equal to the number of data lines (3 for this embodiment) for one output of data-line driving circuitry to perform time-division write, it is possible to almost equalize potential fluctuations generated in all data lines in one vertical period of the external signal and make recognition of a luminance difference between pixels due to potential fluctuation difficult.  
      Furthermore, by using a driving method for writing signals respectively having a polarity equal to that of a common electrode in all pixels in the period in which the liquid-crystal display displays a signal for a screen, it is possible to increase the numerical aperture of a liquid-crystal display and improve the using efficiency of light. A liquid-crystal display normally uses a driving method in which the polarity of a voltage to be applied to each pixel for every frame to a common electrode is reversed in order to prevent deterioration of liquid crystal and in this case, a driving method for applying signals having polarities different from each other to adjacent pixels is generally used. In the case of a liquid-crystal display for a projector, gate-line reverse driving for writing signals having the same polarity in each pixel row and applying signals whose polarities are different between adjacent pixel rows is frequently used in order to eliminate the influence of light leak due to disorder of orientation by changing polarities for every adjacent pixel rows, thereby decreasing flickers, setting a TFT and storage capacitor to positions along a gate line, thereby setting the position of light leak due to disorder of orientation of liquid-crystal molecules generated between adjacent pixels to a portion nearby a region in which the TFT and storage capacitor are arranged, and light-shielding the portion. However, in the case of a liquid-crystal display having a pixel pitch smaller than 20 μm, an area ratio between regions in which disorder of orientation of liquid-crystal molecules to a pixel region occurs increases but it is impossible to increase a numerical aperture and thus, there is a problem that the using efficiency of light is lowered.  
      However, like this embodiment, when performing frame inversion at a high frequency, it is possible to write signals having the same polarity in all pixel electrodes in a certain frame while avoiding the problem of flicker. Thereby, because signals having polarities different from each other are not written between adjacent pixel electrodes, light leak does not occur and it is possible to increase a numerical aperture. Therefore, it is possible to improve the using efficiency of light.  
      For this embodiment, an example in which a video signal is an analog signal is described. However, there is no problem even if processing the video signal as a digital signal.  
      Then, eighth embodiment of the present invention is described below.  FIG. 25  is a timing chart showing operations of the liquid-crystal display of the eighth embodiment of the present invention by assigning time to the axis of abscissa and potential of each wiring to the axis of ordinate. Lights of red (R), green (G), and blue (B) successively emitted from a light source (not illustrated) are successively applied the liquid-crystal display of this embodiment. Because a configuration of the liquid-crystal display of this embodiment is the same as that of the above-described fourth embodiment, its description is omitted. The period TV shown in  FIG. 25  is a vertical period in which video signals for one screen to be supplied to a liquid-crystal display from the outside are supplied.  
      In the case of this embodiment, the vertical period TV is divided into at least three subframe periods and each subframe period is divided into at least two periods. That is, the vertical period TV is divided into subframe periods TSVR, TSVG, and TSVB, the subframe period TSVR is divided into periods TWR and TLR, the subframe period TSVG is divided into a period TWG and TLG, and the subframe period TSVB is divided into periods TWB and TLB. In the period TWR, a video signal having a red component among video signals to be displayed on a liquid-crystal display is written and a light source applies red light to the liquid-crystal display in the period TLR. Similarly in the period TWG, a video signal having a green component is written and in the period TLG, the light source applies green light to the liquid-crystal display. Moreover, in the period TWB, a video signal having a blue component is written and in the period TLB, the light source applies blue light to the liquid-crystal display.  
      In the case of the liquid-crystal display of this embodiment, by performing field sequential driving, it is possible to display a color image in time division without setting a color filter to the liquid-crystal display. Advantages other than the above of this embodiment are the same as those of the above-described fourth embodiment.  
      Then, ninth embodiment of the present invention is described. This embodiment is an execution conformation of a projector system.  FIG. 26  is a block diagram showing the projector system of this embodiment. As shown in  FIG. 26 , the projector system  6   f  this embodiment is a liquid-crystal projector system using three liquid-crystal displays for lights of three primary colors of R, G, and B. A lamp  42  is set to the projector system  41  as a light source and a color separation mirror  43  for passing red light and reflecting green and blue lights is set to a position in an optical path of the light emitted from the lamp  42 . An optical component (not illustrated) for uniforming light and an optical component (not illustrated) for arranging polarization of light are set between the lamp  42  and the color separation mirror  43 .  
      Moreover, a mirror  44  for fully reflecting the light passing through the color separation mirror  43  and a liquid-crystal display  45  for red are set in order so as to be present in the optical path of the light. Furthermore, a color separation mirror  46  for reflecting green light and passing blue light is set so as to be present in the optical path of the light reflected from the color separation mirror  43  and a liquid-crystal display  47  for green light is set so as to be present in the optical path of the light reflected from the color separation mirror  46 . Furthermore, mirrors  48  and  49  for fully reflecting the light passing through the color separation mirror  46  and a liquid-crystal display  50  for blue light are set in order so as to be present in the optical path of the light.  
      Furthermore, a synthesizing prism  51  for synthesizing the light passing through the liquid-crystal display  45  for red light, liquid-crystal display  47  for green light, and liquid-crystal display  50  for blue light is set and a projection lens  52  for widening the synthesized light emitted from the synthesizing prism  51  and projecting the light to an external screen (not illustrated) is set. The liquid-crystal display  45  for red light, liquid-crystal display  47  for green light, and liquid-crystal display  50  for blue light are single-light liquid-crystal displays and used for any one of the above-described embodiments.  
      Then, operations of the projector of this embodiment are described below. The liquid-crystal display  45  for red light, liquid-crystal display  47  for green light, and liquid-crystal display  50  for blue light display a red image, green image, and blue image respectively and a lamp  42  is turned on under this state. Thereby, the white light emitted from a lamp  52  is uniformed and polarization is uniformed. Thereafter, the light reaches the color separation mirror  43  and red component of the white light passes through the color separation mirror  43  and green component and blue component are reflected. Then, the red light passing through the color separation mirror  43  is reflected from the mirror  44 , passes through the liquid-crystal display  45  for red light, and a red image is added to the red light.  
      Moreover, the light reflected from the color separation mirror  43  reaches the color separation mirror  46 , green component is reflected from the color separation mirror  46 , and blue component passes through the mirror  46 . The green light reflected from the color separation mirror  46  passes through the liquid-crystal display  47  for green light and a green image is added to the green light. The blue light passing through the color separation mirror  46  is reflected from the mirrors  48  and  49 , passes through the liquid-crystal display  50  for blue light and a blue image is added to the blue light.  
      Then, the red light to which the red image is added by the liquid-crystal display  45  for red light, green light to which the green image is added by the liquid-crystal display  47  for green light, and the blue light to which the blue image is added by the liquid-crystal display  50  for blue light are synthesized by the synthesizing prism  51 , and these lights become color images and are light-widened and projected to a screen by the projection lens  52 .  
      In the case of the projector system of this embodiment, streak-like irregularity along a data line hardly occurs in a liquid-crystal display built in the projector system. Therefore, streak-like irregularity hardly occurs also on a projected image. Therefore, a high-quality image having no irregularity is obtained even if increasing the number of display gradations compared to the case of a conventional liquid-crystal projector system.  
      It is allowed that a projector system of the present invention is a front-type liquid-crystal projector system or a rear-type liquid-crystal projector system.  
      Then, tenth embodiment of the present invention is described below.  FIG. 27  is a block diagram showing the liquid-crystal display of this embodiment. Symbols “R”, “G”, and “B” in  FIG. 27  show colors of color filters arranged on each pixel. As shown in  FIG. 27 , in the case of the liquid-crystal display of this embodiment, a color filter of red (R), green (G), or blue (B) is set to each pixel. It is allowed to set the color filter to a TFT-side glass substrate or opposite-side glass substrate. Moreover, color filters of the same color are arranged in the row direction, that is, along the direction in which data lines D extend and color filters of different colors are arranged in the column direction, that is, along the direction in which gate lines. G extend. Moreover, in the case of this embodiment, the number of data lines D to be driven by one output of the data-line driving circuitry  5 , that is, the number of data lines D belonging to one group is 6 and the number of colors of color filters is 3 or more. The driving method of the liquid-crystal display of this embodiment is the same as the case of the above-described fourth embodiment. It is also allowed to use the driving method of any one of the above-described embodiments  5  to  8 .  
      When using a conventional liquid-crystal display, by setting the number of data lines to be driven by one output of data-line driving circuitry to 3 which is the same as the number of colors, even if potential fluctuations due to sampling occur, the fluctuation values are equalized for the same color. Therefore, recognition of streak-like irregularity is difficult compared to the case of differentiating the number of data lines to be driven by one output of data-line driving circuitry from the number of colors. However, when making the number of data lines to be driven by one output of data-line driving circuitry more than the number of colors, for example, when setting the number of data lines to be driven by one output to 4 or more and the number of colors to 3, data lines in which potential fluctuations are different occur even for the same color and streak-like irregularity becomes remarkable. However, in the case of this embodiment, even if making the number of data lines to be driven by one output of data-line driving circuitry more than the number of colors, streak-like irregularity is hardly recognized because potential fluctuations of data lines are temporally uniformed.  
      In the case of this embodiment, it is allowed to set color filters of a plurality of colors extending in the column direction, arrange pixels to which color filters of the same color are set in the column direction, that is, along the direction in which gate lines extend, and arrange pixels in which color filters of different colors are arranged in the row direction, that is, along the direction in which data lines extend. An advantage for eliminating streak-like irregularity is obtained. This is because when pixels in which color filters of the same color are set are arranged along the direction in which gate lines extend, even if noticing only a specific color, a signal is written at a timing in which a pixel for displaying the color differs in one horizontal period. This principle is the same as the case of the above-described liquid-crystal display for monochromatic display. As a result, by using the liquid-crystal display of this embodiment, it is possible to greatly decrease the number of streak-like irregularities.  
      For this embodiment, an example is shown in which the number of types of colors of color filters is set to three colors of R, G, and B. However, the present invention is not restricted to the above example. It is also allowed to use four colors of R, G, B, and W (white).  
      Moreover, the liquid-crystal display of each of the above described embodiments can be used as a display of a portable terminal unit such as a cellphone, Personal Digital Assistance (PDA: Portable information terminal), game machine, digital camera, or video camera.  
      There are a front-type liquid-crystal projector system, rear-type liquid-crystal projector system, and portable terminal unit as effectively using examples of the present invention.  
      The previous description of embodiments is provided to enable a person skilled in the art to make and use the present invention. Moreover, various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles and specific examples defined herein may be applied to other embodiments without the use of inventive faculty. Therefore, the present invention is not intended to be limited to the embodiments described herein but is to be accorded the widest scope as defined by the limitations of the claims and equivalents.  
      Further, it is the inventor&#39;s intent to retain all equivalents of the claimed invention even if the claims are amended during prosecution.