Abstract:
An image display device has a display pixel area having plural pixels arranged in a matrix fashion, plural signal lines for supplying display signal voltages to the pixels, and plural pixel selection lines for selecting pixels from among the pixels to be supplied with the display signal voltages. The pixel selection lines include Y-direction selection lines for selecting rows of the pixels arranged in the matrix fashion and X-direction selection lines for selecting columns of the pixels, and the image display device includes a circuit configuration in which the display signal voltages are supplied from the signal lines to only ones of the pixels each having selected simultaneously both of a corresponding one of the Y-direction selection lines and a corresponding one of the X-direction selection lines.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This is a continuation of U.S. application Ser. No. 11/062,824, filed Feb. 23, 2005, which is a continuation of U.S. application Ser. No. 09/975,934, filed Oct. 15, 2001 (now abandoned), which is a continuation of U.S. application Ser. No. 09/043,534, filed Mar. 20, 1998 (now U.S. Pat. No. 6,329,973), which is a national stage application under 35 USC 371 of PCT/JP95/01886, filed Sep. 20, 1995, the contents and subject matter of all of the above is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an image display for displaying image data on an image display part constructed by a display pixel array. 
         [0003]    Conventional techniques will be described hereinbelow with reference to  FIGS. 8 and 9 .  FIG. 8  shows a first conventional example of an image display. A data communication line for supplying compressed image information and a CD-ROM  34  serving as a database are connected to an image data generating apparatus  81 . Image data generated by the image data generating apparatus  81  is sequentially inputted to a liquid crystal driver  82  serving as an image data writing means. The liquid crystal driver  82  transfers the image data to a TFT liquid crystal panel  84  constructed by a pixel array. A shift register  83  is provided at the end of the TFT panel  84 . 
         [0004]    The operation of the first conventional technique will be described. In accordance with a request of the image data generating apparatus  81 , image information compressed according to the MPEG1 standard is supplied from the communication line or the CD-ROM  34  to the image data generating apparatus  81 . The image data generating apparatus  81  sequentially inputs image data of each frame to the liquid crystal driver  82 . Each time the image data of pixels of one horizontal line is accumulated, the liquid crystal driver  82  inputs the image data pixels of one horizontal line in a lump to the TFT liquid crystal panel  84 . The shift register  83  sequentially designates the row on the pixel array to which the image data is inputted. 
         [0005]    The image display having such a TFT liquid crystal display is described, for example, in S. Kaneko, “Color TFT Liquid Crystal Display, Journal of the Institute of Electronics, Information and Communication Engineers of Japan, Vol. 78, No. 7, pp. 662-667, July 1995 (in Japanese). 
         [0006]      FIG. 9  shows a second conventional technique of the image display. A data communication line for supplying compressed image information and the CD-ROM  34  as a database are connected to an image data generating apparatus  91 . Image data generated by the image data generating apparatus  91  is inputted to a liquid crystal driver  92  as an image data writing means. The liquid crystal driver  92  transfers the image data to a ferroelectric liquid crystal panel  94  constructed by a pixel array. A decoder  93  is provided at an end of the ferroelectric liquid crystal panel  94 . 
         [0007]    The operation of the second conventional technique will be described. In accordance with a request of the image data generating apparatus  91 , image information compressed according to the MPEG1 standard is supplied from the communication line or the CD-ROM  34  to the image data generating apparatus  91 . The image data generating apparatus  91  inputs image data of only rows including a part (called a moving picture part) changed from the previous frame as rewriting part image data to the liquid crystal driver  92 . Each time image data of (one row of) pixels of one horizontal line is accumulated, the liquid crystal driver  92  inputs the image data of pixels of one horizontal line in a lump to the ferroelectric liquid crystal panel  94 . The decoder  93  designates a row on the pixel array to which the image data is inputted. With respect to a still picture part, previous rewriting image data is stored by using a memory function of the ferroelectric liquid crystal. 
         [0008]    The image display having the ferroelectric liquid crystal display is described, for example, in Y. Inaba et al., “Ferroelectric LCD”, Journal of the Institute of Electronics, Information and Communication Engineers of Japan, Vol. 78, No. 7, pp. 676-679, July 1995 (in Japanese). 
       SUMMARY OF THE INVENTION 
       [0009]    According to the first conventional technique, all of the display pixels are rewritten every frame. Since the number of display pixels are as small as, for example, about (640×480), it is not so difficult. However, in order to realize a high picture quality image display in which the number of display pixels is (thousands×thousands), a rewriting speed of the display pixels is increased by one order of magnitude. It is therefore difficult to realize the display by using the rewriting operation of the first conventional technique. 
         [0010]    According to the second conventional technique, the rewriting part in a frame is reduced by using the memory function of the ferroelectric liquid crystal, thereby reducing the rewriting amount per unit time. It is, however, substantially difficult for the ferroelectric liquid crystal to store data at a multivalued level and the ferroelectric liquid crystal cannot store a full color still image. In order to display the full color still image, it is therefore necessary to rewrite every frame. In a manner similar to the first conventional technique, a problem of the display pixel rewriting speed occurs also in the second conventional technique. 
         [0011]    It is an object of the invention to provide an image display in which a problem of a rewriting speed does not occur. 
         [0012]    The object can be achieved by an image display for displaying image data on an image display part constructed by a display pixel array, in which the display pixel array has an image data inputting means which can input image data so that the display pixel array has two neighboring areas having different frame rates (&gt;0). 
         [0013]    The object can be also achieved by providing image data inputting means which can input at least one moving image data and at least one still image data to an image display part at different frame rates (&gt;0). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a diagram showing the construction of a first embodiment; 
           [0015]      FIG. 2  is a diagram showing the internal construction of a display pixel array of the first embodiment; 
           [0016]      FIG. 3  is a diagram for illustrating how a moving image and a still image are written to the display pixel array of the first embodiment; 
           [0017]      FIG. 4  is a diagram illustrating an operating state of the first embodiment; 
           [0018]      FIG. 5  is a diagram showing the construction of a child device in a second embodiment; 
           [0019]      FIG. 6  is a diagram showing the construction of a write signal generating circuit and a display pixel array in a third embodiment; 
           [0020]      FIG. 7  is a diagram showing the construction of a parent device in a fourth embodiment; 
           [0021]      FIG. 8  is a diagram showing the construction of a first conventional technique; and 
           [0022]      FIG. 9  is a diagram showing the construction of a second conventional technique. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
       [0023]    A first embodiment of the invention will be described hereinbelow with reference to  FIGS. 1 to 4 . 
         [0024]      FIG. 4  is a diagram illustrating an operating state of the embodiment. A parent device  31  of an image display according to the embodiment is fixedly arranged in a house or the like and is connected to a communication line. Image data generated by the parent device  31  is transferred to a child device  1  by microwave and is displayed on the child device  1 . The user uses the child device  1  in his hands and puts it on a charger  54  connected to the parent device  31  when the child device is not used. 
         [0025]    The construction of the embodiment will be described hereinbelow with reference to  FIGS. 1 and 2 .  FIG. 1  is a diagram showing the construction of the embodiment. A data communication line for supplying compressed image information and a CD-ROM  34  as a database are connected to an image data generating apparatus  33 . Further, a radio interface  32  for transferring generated image data by a microwave is connected to the image data generating apparatus  33 . Those elements are provided for the parent device  31  of the image display. Information is transferred and received wirelessly between the radio interface  32  in the parent device  31  and a radio interface  2  in the child device  1 . Four kinds of outputs are supplied from the radio interface  2 . A first output is supplied to a moving image decoder  3  and to a write signal generating circuit  17  via a moving image write line  4 . A second output is supplied to a still image decoder  5 , a still image memory  6 , and to the write signal generating circuit  17  via a still image write line  7 . A third output is supplied to a text code memory  8 , an outline font generating circuit  9 , and to the write signal generating circuit  17  via a text write line  11 . A fourth output is supplied to an icon/window address memory  12 , an icon/window generating circuit  13 , and to the write signal generating circuit  17  via an icon/window write line  15 . An outline font ROM  10  and an icon/window ROM  14  are connected to the outline font generating circuit  9  and the icon/window generating circuit  13 , respectively. An icon/window position detecting circuit  16  is also connected to the icon/window address memory  12 . A timing generating circuit  20  is also provided and outputs of the position detecting circuit  16  and the timing generating circuit  20  control the still image memory  6 , the text code memory  8 , and the icon/window address memory  12  (the outputs are omitted here). 
         [0026]    A display pixel array  18  for displaying an image by using a TN liquid crystal is further connected to the write signal generating circuit  17 . The display pixel array  18  has a touch sensor and an output of the touch sensor is inputted to the radio interface  2  via a touch sensor output generating circuit  19 . 
         [0027]      FIG. 2  is a diagram showing the internal construction of the display pixel array  18 . Display pixels are arranged in a matrix state in a display pixel area  53 . Each pixel is constructed by a TN liquid crystal capacitor  49 , a TFT switch  48  connected to the TN liquid crystal capacitor  49 , and an AND gate circuit  47  for driving the gate of the TFT switch  48 . The AND gate circuit  47  and the TFT switch  48  are formed by a CMOS process of a poly-Si TFT. The other terminal of the TFT switch  48  is connected to a signal line  45  and input terminals of the AND gate circuit  47  are connected to a vertical direction gate selection line  50  and a horizontal direction gate selection line  46  in the row and column directions, respectively. A moving image signal output circuit  43  and a still image signal output circuit  41  are connected to the signal line  45 . A moving image vertical direction selecting circuit  52  and a still image vertical direction selecting circuit  51  are connected to the vertical direction gate selection line  50 . A moving image horizontal direction selecting circuit  44  and a still image horizontal direction selecting circuit  42  are connected to the horizontal direction gate selection line  46 . The moving image signal output circuit  43 , the still image signal output circuit  41 , the moving image vertical direction selecting circuit  52 , the still image vertical direction selecting circuit  51 , the moving image horizontal direction selecting circuit  44 , and the still image horizontal direction selecting circuit  42  are connected to the write signal generating circuit  17 . 
         [0028]    The operation of the embodiment will be described hereinbelow with reference to  FIGS. 1 ,  2 , and  3 . As shown in  FIG. 1 , compressed image information inputted from the data communication line and the CD-ROM  34  as a database is divided by the image data generating apparatus  33  into moving image data, still image data, text data, figure information, and icon and window data, the data is subjected to a predetermined coding process, and the resultant data is inputted to the radio interface  32 . The image data is inputted from the parent device radio interface  32  to the child device radio interface  2  and is inputted to predetermined signal processing systems in accordance with the kinds of the data. That is, the moving image data is converted to a video signal by the moving image decoder  3 , which is supplied to the write signal generating circuit  17  via the moving image write line  4 . The still image is converted to video signals by the still image decoder  5 . After that, the video signal is once written in the still image memory  6 . The still image data is sequentially inputted to the write signal generating circuit  17  via the still image writing line  7  at predetermined timings. The text data and the figure information are once stored in a text code form or the like in the text code memory  8 . The text data and the figure information is sequentially read by the outline font generating circuit  9  at a predetermined timing and is converted into still image data. After that, the still image data is inputted to the write signal generating circuit  17  via the text writing line  11 . The icon and window data is once stored in a state of a data code and image address data into the icon/window address memory  12 . The icon and window data is sequentially read by the icon/window generating circuit  13  at a predetermined timing and is converted to still image data. After that, the still image data is inputted to the write signal generating circuit  17  via the icon/window writing line  15 . 
         [0029]    The reading operation of data from the still image memory  6 , the text code memory  8 , and the icon/window address memory  12  is controlled by the timing generating circuit  20  as will be described hereinlater. Changes in the position and shape of the icon and the window are detected by the icon/window position detecting circuit  16 . When those changes are detected, the icon/window position detecting circuit  16  interrupts the inputting operation of the still image data controlled by the timing generating circuit  20  to the write signal generating circuit  17  and writes still image data to display pixel addresses of a part in which the position or shape of the icon and the window is changed. 
         [0030]    The write signal generating circuit  17  sends a write signal to the display pixel array  18  on the basis of inputted image data, which will be described hereinlater with reference to  FIG. 2 . The display pixel array  18  has the touch sensor. Address information instructed by the tip of a finger or the like is inputted to the touch sensor output generating circuit  19  and to the image data generating apparatus  33  via the radio interfaces  2  and  32  and a command of the operator is transmitted. 
         [0031]    The operation of the display pixel array  18  will be described with reference to  FIG. 2 . 
         [0032]    The write signal generating circuit  17  divides the image data into a moving image and a still image and outputs data and addresses of each of the images. The data of the moving image is supplied to the moving image signal output circuit  43  and the address of the moving image is outputted to the moving image vertical direction selecting circuit  52  and the moving image horizontal direction selecting circuit  44 . The data of the still image is outputted to the still image signal output circuit  41  and the address of the still image is outputted to the still image vertical direction selecting circuit  51  and the still image horizontal direction selecting circuit  42 . 
         [0033]    When an image signal is written in the display pixel, the moving image vertical direction selecting circuit  52  selects an address in the row direction and the moving image horizontal direction selecting circuit  44  selects an address of the moving image in the selected row. As a result, the AND gate circuit  47  of the selected display pixel is turned on and the connected TFT switch  48  is turned on. By converting the moving image data, the moving image signal output circuit  43  generates a signal voltage to be inputted to each of the selected display pixels and applies the signal voltage to the signal line  45 . The signal voltage is inputted to the TN liquid crystal capacitor  49  via the TFT switch  48 . Since the signal writing method of the still image is similar to that of the moving image, its description is omitted here. 
         [0034]    Timings of writing the moving and still images to the display pixel array  18  will be described with reference to  FIG. 3 .  FIG. 3  illustrates how to write the moving and still images to the display pixel array  18 . The display pixels are shown in circles in the display pixel area  53 . For simplicity, the display pixel array has 8 rows×12 columns. Among the display pixels, those with reference characters (a) to (d) are display pixels of the moving image and the other are display pixels of the still images. When it is assumed that a leak of current from the TN liquid crystal capacitor  49  is sufficiently small and flicker is not conspicuous if a refresh writing operation is performed (m) times per second and that (n) moving images are inputted per second. When the display pixels of the still image display area has (j) rows and the display pixels of the moving display area has (k) rows, the ratio of the writing rows of the still image to the moving image per unit time is (m×j):(n×k). For example, when (m) is 10, (n) is 60, (j) is 8, and (k) is 4, the ratio is 1:3. It is understood that the writing operation in the ratio of three writing rows of the moving image to one writing row of the still image is sufficient. 
         [0035]    With respect to other examples of numerical values, it is assumed that the display pixel array  18  displaying the still image has 5000 rows of pixels and a moving picture displayed 30 frames per second on the display pixel array  18  has 500 scan lines. In this case as well, it is assumed that the leak current from the TN liquid crystal capacitor  49  is sufficiently suppressed and the flicker is not conspicuous in a still image if the refresh writing operation is executed once per second, the ratio of the writing rows per unit time of the still image to the moving image can be set to 1:3 by the above-mentioned equation. As compared with a case where 30 frames of a moving image each having 500 scan lines are displayed per second, the speed of writing data to the display pixel array is increased only by 33% ((1+3)/3=1.33). However, a display at a present time point of a general VGA specification is performed with about 480 rows and 60 frames/second. Consequently, the writing speed of 500 rows and 30 frames/second in the embodiment which is 33% higher has an advantage that the writing speed can be reduced to about 70% of that of a general display at present (1.33×(500/480)×(30/60)=0.69). 
         [0036]    When the refresh writing frame rate of the still image is decreased as mentioned above, a flicker occurs in an image. When the writing to the display pixel is not performed by a sequential scan but the image is divided into (g) fields and a writing scan is intermittently performed every (g) rows, the flicker is suppressed more and the writing operation at a lower frame rate can be performed. 
         [0037]    Although the microwave is used to transfer data from the parent device  31  to the child device  1  in the foregoing embodiment, it is obviously understood that other data transfer means such as infrared light, wire, and the like can be also used. 
         [0038]    The same unit of one display pixel is used for both of the moving image and the still image in the embodiment. However, since the precision as high as that of the still image is not generally required in the moving image, (2×2) or arbitrary (h×i) display pixels in the still image can be used as a unit of display pixels in the moving image. When signals are written to the (h×i) display pixels at the same timing, unnecessary increase in writing speed can be prevented. 
         [0039]    An image signal accuracy of about 6 bits is requested in the moving image and that of about 8 bits is required in the still image. Consequently, when the accuracy of the converter of the moving image signal output circuit  43  and that of the still image signal output circuit  41  are changed to 6 bits and 8 bits, respectively, the bit accuracy of the moving image signal output circuit  43  which is requested to operate at higher speed becomes lower, so that designing of the converter is facilitated. 
         [0040]    Although a case where one moving picture display area is surrounded by one still picture display area has been described in the embodiment, according to the idea of the invention, if the moving and still picture display areas having different frame rates exist, the effects of the invention can be obtained irrespective of the number of areas and arrangement of the areas. The effects of the invention can be also obtained when still picture display areas having different frame rates are neighboring. 
       Second Embodiment 
       [0041]    A second embodiment of the invention will be described hereinbelow with reference to  FIG. 5 .  FIG. 5  is a diagram illustrating the construction of a child device  60  in the embodiment. Since the construction and operation of the parent device  31  are similar to those in the first embodiment, their description are omitted here. 
         [0042]    The difference between the present embodiment and the first embodiment is as follows. In the first embodiment, the elements from the radio interface  2  to the signal generating circuit  17  are constructed by an electronic circuit as hardware. On the contrary, in the second embodiment, the same function is realized by software on a microcomputer  61  and an image memory  62  having parallel output ports. The second embodiment can also obtain effects similar to those of the first embodiment. 
         [0043]    Especially, when the number of output ports of the image memory  62  is set to the same as the number of pixels in the column direction of the display pixel array part, it is convenient from the viewpoint of the layout of the signal generating circuit  17 . 
       Third Embodiment 
       [0044]    A third embodiment of the invention will be described hereinbelow with reference to  FIG. 6 .  FIG. 6  is a diagram showing the construction of a write signal generating circuit  71  and a display pixel array  72  according to the third embodiment. The difference of the third embodiment from the first embodiment is that a two-gradation still image signal output circuit  63  is provided and an output of the two-gradation still image signal output circuit  63  is used to write binary image data. 
         [0045]    In case of using the two-gradation still image signal output circuit  63 , a converter is unnecessary so that power consumption is very small. For image data using monochromatic color or only multicolors of 8 colors, the power source of the still image signal output circuit  41  is temporarily stopped, thereby enabling the power consumption to be reduced. 
       Fourth Embodiment 
       [0046]    A fourth embodiment of the invention will be described hereinbelow with reference to  FIG. 7 .  FIG. 7  is a diagram showing the construction of a parent device  64  in the embodiment. The difference of the fourth embodiment from the first embodiment is that another child device  65  having a large screen  66  is connected to an image data generating apparatus  73  and the child device  1  (not shown) and the child device  65  commonly use the system of the parent device  64 . 
         [0047]    According to the embodiment, a plurality of child devices are controlled by the single parent device  64 , thereby reducing the cost. 
         [0048]    According to the embodiments, the image display having high picture quality of hundreds of dots/inch which is about the same as that of a printed matter and (thousands×thousands) display pixels can be realized without hardly increasing the rewriting speed of the display pixels.