Patent Publication Number: US-2011050861-A1

Title: Stereoscopic image display device and stereoscopic image display method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-201064, filed Aug. 31, 2009, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     One embodiment of the invention relates to improvement of a stereoscopic image display device and a stereoscopic image display method capable of displaying a stereoscopic image by applying illumination light from a backlight to a liquid crystal display panel or the like. 
     2. Description of the Related Art 
     As is well known, there has been developed a technique of making a user recognize a stereoscopic image with use of a planer image display screen. In this technique, stereoscopic vision is obtained by preparing two images with parallax corresponding to the distance between the eyes, making the right eye recognize a right-eye image and the left eye recognize a left-eye image. 
     Specifically, there exists a technique of making a user recognize a stereoscopic image by displaying right- and left-eye images on the same image display screen alternately and controlling a pair of stereoscopic glasses the user wears in such a manner that a left-eye shutter is closed when the right-eye image is displayed and a right-eye shutter is closed when the left-eye image is displayed. 
     Meanwhile, there has recently been a rapid spread of an image display device using a liquid crystal display panel for displaying images. This type of image display device displays images by allowing illumination light from a backlight, which has a cold-cathode tube such as a discharge lamp or a fluorescent tube as a light source, to pass through the liquid crystal display panel from its backside. 
     At present, there is developed a local dimming technique of making the backlight of a plurality of light sources and controlling the emitted light amount of each light source in accordance with partial brightness of the display image on the same screen to make a dark part darker and a bright part brighter on the same screen thereby enhancing the contrast. 
     With development of this local dimming technique, needless to say, it is considered that stereoscopic images are displayed using an image display device to which the local dimming technique is applied. However, such a local dimming technique is still developing and has room for improvement at various points when being used in displaying images for stereophonic vision. 
     For example, the right- and left-eye images displayed alternately for stereoscopic vision have mutual parallax and when small areas at the same position in the respective images are compared, there sometimes exists the same subject and sometimes not. In this case, if the luminous of the subject is high, a high-luminous image and a low-luminous image are displayed alternately for the small areas. 
     Here, consideration is given to the emitted light amount of each of plural light sources that make up the above-mentioned backlight. Specifically, each light source for applying illumination light to the above-mentioned small area is controlled to emit much light (be brighter) when displaying of an image in which the subject exists and emit less light (be darker) when displaying of an image in which no subject exists. 
     However, the emitted light amount of each of the plural light sources that make up the backlight is controlled to change slowly in the time axis direction in order to prevent the user from recognizing sequential transition of the light emission of the light source in accordance with the motion of the display image when displaying of a typical moving image. 
     Therefore, the light source for applying the illumination light to the above-mentioned small area is controlled to emit light at the approximately intermediate amount between the emitted light amount when displaying the image with the subject and the emitted light amount when displaying the image with no subject, which sometimes makes the user feel that the display image is dark. 
     Jpn. Pat. Appln. KOKAI Publication No. 2007-279395 discloses a structure in which a luminous value of an image displayed on each of a plurality of display areas divided from a display screen is obtained, a peak luminous value of each of the display areas is detected and the brightness of illumination light applied from illuminating means which illuminates the image displayed on the display screen is controlled per display area in accordance with the peak luminous value. 
     Jpn. Pat. Appln. KOKAI Publication No. 2008-268396 discloses a structure in which display means is provided which has a plurality of unit display areas arranged for displaying first and second images with parallax for stereoscopic viewing, and a monochromatic image of each of plural color components that make each of the first and second images is sequentially displayed per one or more unit display areas out of the plural unit display areas. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention. 
         FIG. 1  is a block diagram illustrating one embodiment of the present invention and for explaining one example of a signal processing system of a stereoscopic image display device; 
         FIG. 2  is a view for explaining one operation example of a serial processing module of the stereoscopic image display device according to the embodiment; 
         FIG. 3  is a timing chart for explaining one example of the relationship between right- and left-eye images displayed on the stereoscopic image display device according to the embodiment and shutter control of a pair of stereoscopic glasses; 
         FIG. 4  is a plan view for explaining one example of a liquid crystal display panel of the stereoscopic image display device according to the embodiment; 
         FIG. 5  is a plan view for explaining one example of a backlight of the stereoscopic image display device according to the embodiment; 
         FIG. 6  is a side view for explaining one example of the relationship between the backlight and the liquid crystal display panel of the stereoscopic image display device according to the embodiment; 
         FIG. 7  is a block diagram for explaining one example of a backlight controller of the stereoscopic image display device according to the embodiment; 
         FIG. 8  is a block diagram for explaining one example of a control value storage and an all-area maximum value storage that make up the backlight controller according to the embodiment; 
         FIG. 9  is a block diagram for explaining one example of an LPF of the backlight controller according to the embodiment; 
         FIG. 10  is a characteristic view for explaining one example of filtering processing in the time axis direction of the LPF according to the embodiment; 
         FIG. 11  is a view for explaining one example of a right-eye image displayed on the stereoscopic image display device according to the embodiment and a lighting state of the backlight; 
         FIG. 12  is a view for explaining one example of a left-eye image displayed on the stereoscopic image display device according to the embodiment and a lighting state of the backlight; 
         FIG. 13  is a view for explaining one example of an image generated by the stereoscopic image display device according to the embodiment and a lighting state of the backlight; 
         FIG. 14  is a block diagram for explaining a modification of the stereoscopic image display device according to the embodiment; 
         FIG. 15  is a timing chart for explaining an example of the operation performed by the modification of the stereoscopic image display device according to the embodiment; and 
         FIG. 16  is a timing chart for explaining another example of the operation performed by the modification of the stereoscopic image display device according to the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, astereoscopic image display device obtains a substantially greater value of a maximum value of luminous when displaying a first stereoscopic image and a maximum value of luminous when displaying a second stereoscopic image in each of plural areas divided from a display panel surface corresponding to plural light sources which illuminate the display panel thereby to control the emitted light amount of the light source corresponding to the area. 
       FIG. 1  illustrates a signal processing system of a stereoscopic image display device  11  explained in this embodiment. This stereoscopic image display device  11  comprises two input terminals  12  and  13 . The input terminal  12  receives a right-eye image signal to form a right-eye image at the frame period of 1/60 second, as illustrated in (a) of  FIG. 2 . In addition, the other input terminal  13  receives a left-eye image signal to form a left-eye image at the frame period of 1/60 second, as illustrated in (b) of  FIG. 2 . 
     These right- and left-eye image signals can be obtained, for example, by receiving what a broadcasting company transmits as a stereoscopic image signal. In addition, they can be also obtained from a contents provider via network or the like or reproduction from a recording medium such as an optical disk. 
     The right- and left-eye image signals supplied to these input terminals  12  and  13  are supplied to a serial processing module  14 . This serial processing module  14  receives these right- and left-eye image signals supplied to the input terminals  12  and  13  and outputs signals in such a manner that they are arranged alternately per frame at the frame period of 1/120 second, as illustrated in (c) of  FIG. 2 . The image signal output from the serial processing module  14  is supplied to a liquid crystal display panel controller  15  and a backlight controller  16 . 
     The liquid crystal panel controller  15  controls to form a display image of one frame on a later-stage liquid crystal display panel  17  by writing an image signal corresponding to the one frame output from the serial processing module  14  in plural pixels that make up the liquid crystal display panel  17 . 
     In addition, the above-mentioned backlight controller  16  controls a later-stage backlight  19  that performs image display by applying illumination light to the back surface side of the liquid crystal display panel  17 . That is, this backlight controller  16  uses the image signal output from the serial processing module  14  as a basis to calculate an emitted light amount control value so as to control the emitted light amount (brightness) of each of plural light sources that make up the backlight  19  to correspond to partial luminous of the display image of one frame formed on the liquid crystal display panel  17 . 
     Then, the emitted light amount control value calculated by this backlight controller  16  is supplied to a backlight driving module  18 . This backlight driving module  18  uses the emitted light amount control value supplied from the backlight controller  16  as a basis to control the emitted light amount of each of the plural light sources that make up the backlight  19  thereby to perform image display to which the local dimming technique is applied. 
     Here, the above-described liquid crystal display panel controller  15  is supplied with the emitted light amount control value calculated by the backlight controller  16 . Then, the liquid crystal display panel controller  15  performs correction processing based on the emitted light amount control value calculated by the backlight controller  16  on the image signal output from the serial processing module  14  and outputs the signal to the liquid crystal display panel  17 . 
     In addition, the above-mentioned serial processing module  14  outputs to a glasses controller  20  a signal indicating a timing of outputting right- and left-eye image signals alternately on a frame-by-frame basis. This glasses controller  20  uses the timing signal supplied from the serial processing module  14  as a basis to generate a right-eye shutter control signal and a left-eye shutter control signal for a pair of stereoscopic glasses  21  the user wears. 
     That is, this glasses controller  20  controls to close the left-eye shutter of the stereoscopic glasses  21  when the right-eye image is displayed and close the right-eye shutter of the stereoscopic glasses  21  when the left-eye image is displayed. This control makes the user recognize the stereoscopic image. 
       FIG. 3  illustrates the relationship between the right- and left-eye images displayed on the liquid crystal display panel  17  and the right- and left-eye shutter control of the stereoscopic glasses  21 . Here, it is assumed that right-eye image signals R 1 , R 2 , . . . at the frame period of 1/60 second as illustrated in (a) of  FIG. 3  are supplied to the above-mentioned input terminal  12  and the left-eye image signals L 1 , L 2 , . . . at the frame period of 1/60 second as illustrated in (b) of  FIG. 3  are supplied to the above-mentioned input terminal  13 . 
     Then, the serial processing module  14  outputs, as illustrated in (c) of  FIG. 3 , right- and left-eye image signals alternately at the frame period of 1/120 second, based on which the right- and left-eye images are displayed alternately on the liquid crystal display panel  17 . 
     Then, as illustrated in (d) of  FIG. 3 , the above-mentioned glasses controller  20  outputs a right-eye shutter control signal to open the right-eye shutter of the stereoscopic glasses  21  at the high level occurring when the right-eye image is displayed and close the right-eye shutter of the stereoscopic glasses  21  at the low level occurring when the left-eye image is displayed. 
     In addition, as illustrated in (e) of  FIG. 3 , the glasses controller  20  outputs a left-eye shutter control signal to open the left-eye shutter of the stereoscopic glasses  21  at the high level occurring when the left-eye image is displayed and close the left-eye shutter of the stereoscopic glasses  21  at the low level occurring when the right-eye image is displayed. 
     Here,  FIG. 4  illustrates one example of the above-described liquid crystal display panel  17 . Specifically, this liquid crystal display panel  17  is configured to have a plurality of pixels  22 , each of which is a liquid crystal cell, arranged in the horizontal and vertical directions into a matrix shape. In this case, a panel surface of the liquid crystal display panel  17  is divided into a plurality of areas (j×k areas)  23  arranged to have j areas in the horizontal direction and k areas in the vertical direction. Each of the areas  23  includes a plurality of pixels (n×m pixels)  22  arranged to have n pixels in the horizontal direction and m pixels in the vertical direction. 
     Further,  FIG. 5  illustrates one example of the above-mentioned backlight  19 . Specifically, the backlight  19  has a plurality of light sources (j×k)  24  arranged in a matrix shape in such a manner that there are j light sources in the horizontal direction and k light sources in the vertical direction, corresponding to the respective areas  23  of the above-mentioned liquid crystal display panel  17 . Each of these light sources  24  is an LED (light emitting diode) or the like. 
     More specifically, as illustrated in  FIG. 6 , the backlight  19  comprises light sources  24 , such as white LED array, which are arranged to have j light sources in the horizontal direction and k light sources in the vertical direction. Each of the light sources  24  is covered with a light reflector  25 , and a diffusing plate  26  is arranged on the irradiation surface of the light so that even light irradiation can be achieved on each area  23 . Then, this backlight  19  is placed on the back surface side of the liquid crystal display panel  17  and radiates light to the back surface of the liquid crystal display panel  17  so as to display images. 
       FIG. 7  illustrates an example of the above-mentioned backlight controller  16 . This backlight controller  16  comprises input terminals  27 ,  28  and  29  which are supplied with red (R), green (G) and blue (B) image signals, respectively, output from the serial processing module  14 . These R, G and B signals supplied to the input terminals  27  to  29  are input to a luminous converter  30 , in which they are converted to a luminous signal Y. 
     The luminous signal Y output from this luminous converter  30  is supplied to an n-pixel maximum value detector  31 . This n-pixel maximum value detector  31  detects a maximum value of luminous in each area  23 , which is each n pixels out of plural (n×j) pixels that make up one horizontal line, and output its resultant value to one input terminal of a comparator  32 . 
     Once the n-pixel maximum value detector  31  detects the maximum value of luminous for each of the j areas in the one horizontal line, the n-pixel maximum value detector  31  then detects a maximum value of luminous for each area  23 , that is, each n pixels out of plural (n×j) pixels that make up the next horizontal line and repeats this operation. 
     Further, the other input terminal of the above-mentioned comparator  32  is supplied with values of luminous stored in a j-area maximum value storage  33 . This j-area maximum value storage  33  has luminous maximum value storage areas corresponding to j areas  23  arranged in the horizontal direction. Then, the comparator  32  compares a maximum value of luminous of a given area  23  supplied from the n-pixel maximum value detector  31  with a value of luminous read from a luminous maximum value storage area of the j-area maximum value storage  33  corresponding to the given area  23 , selects a substantially greater value of them and stores the value in the same luminous maximum value storage area of the j-area maximum value storage  33 . 
     In this case, it is assumed that the value of luminous stored in the j-area maximum value storage  33  to be compared with the maximum value of luminous detected in the first horizontal line in each area  23  by the n-pixel maximum value detector  31  is “0”, and a comparison result in the same area  23  obtained by the comparator  32  is stored in the luminous maximum value storage area of the corresponding area  23  in the j-area maximum value storage  33 . 
     Then, when the processing of detecting the maximum values of luminous for the j areas  23  in the m horizontal lines by the n-pixel maximum value detector  31  is finished, during its detection processing, the comparator  32  outputs a maximum value of luminous of each of the j areas  23  in the horizontal direction. 
     In this way, the maximum values of luminous in the j areas  23  in the horizontal direction output from the comparator  32  are written in the all-area maximum value storage  34 . 
     The operation described up to this point is repeated k times in the vertical direction so that maximum values of luminous in all of the j×k areas  23  in the liquid crystal display panel  17  are obtained and written in the all-area maximum value storage  34 . 
     Then, the maximum values of luminous in all of the areas  23  written in the all-area maximum value storage  34  are subjected to the filtering processing in the time axis direction by a low-pass filter (LPF)  35  and then, written in the control value storage  36  as emitted light amount control values to control the emitted light amounts of the plural (j×k) light sources  24  that make up the above-mentioned backlight  19 . 
     Then, the emitted light amount control value of each of the light sources  24  written in this control value storage  36  is supplied to the backlight driving module  18  via the output terminal  37 . 
     Here, the above-mentioned LPF  35  performs the filtering processing, based on the previous emitted light amount control values written in the control value storage  36 , on the maximum values of luminous supplied from the all-area maximum value storage  34 . 
       FIG. 8  illustrates an example of the all-area maximum value storage  34  and the control value storage  36 . That is, in the all-area maximum value storage  34 , maximum values of luminous of the areas  23  output from the comparator  32  are supplied to an input terminal  34   a . The maximum values of luminous supplied to this input terminal  34   a  are supplied to a writing/reading controller  34   b  and stored, on a per-area basis, in plural (j×k) maximum value storages  34   c  which are arranged to have j storages in the horizontal direction and k storages in the vertical direction corresponding to the respective areas  23 . 
     In this case, each of the maximum value storages  34   c  comprises a right-eye maximum value storage area  34   c   1  to store the maximum value of luminous of a corresponding area  23  for the right-eye image and a left-eye maximum value storage area  34   c   2  to store the maximum value of luminous of the corresponding area  23  for the left-eye image. 
     Therefore, in the right-eye maximum value storage area  34   c   1  and the left-eye maximum value storage area  34   c   2  of each of the maximum value storages  34   c , the maximum values of luminous of the corresponding area  23  in the one-frame right- and left-eye image signals output alternately from the serial processing module  14  are stored. 
     Then, the above-mentioned writing/reading controller  34   b  selects a substantially greater value out of maximum values of luminous stored in the left-eye maximum value storage area  34   c   2  and the right-eye maximum value storage area  34   c   1  of each of the maximum value storages  34   c  and outputs it to the LPF  35  via the output terminal  34   d.    
     This LPF  35  performs the filtering processing in the time axis direction based on the previous emitted light amount control values written in the control value storage  36  on the maximum values of luminous of the respective areas  23  output from the all-area maximum value storage  34 , and outputs the values to the control value storage  36 . 
     In this case, in the above-mentioned control value storage  36 , a maximum value of luminous at each area  23  output from the LPF  35  is supplied to the input terminal  36   a . This maximum value of luminous, which is subjected to the filtering processing and supplied to the input terminal  36   a , is supplied to a writing/reading controller  36   b . Then, the value is stored as an emitted light amount control value, on a per-area basis, in a corresponding one of the plural (j×k) emitted light amount storages  36   c  arranged in such a manner that there are j storages in the horizontal direction and k storages in the vertical direction corresponding to the respective areas  23 . 
     Then, the writing/reading controller  36   b  outputs the emitted light amount control value stored in each of the emitted light amount control value storages  36   c  via the output terminal  36   d  to the above-mentioned backlight driving module  37  and to the LPF  35 . In this case, the backlight driving module  37  uses the emitted light amount control value read from each emitted light amount control value storage  36   c  as a basis to control the emitted light amount of the light source  24  of the corresponding area  23 . 
     That is, in the backlight controller  16  illustrated in  FIG. 7 , a maximum value of luminous in the right-eye image and a maximum value of luminous in the left-eye image are obtained for each of plural (j×k) areas  23  divided from the panel screen of the liquid crystal display panel  17 . Then, a substantially greater value of the maximum values of luminous in the left- and right-eye images is selected and set as an emitted light amount control value for controlling the emitted light amount of the light source  24  of the corresponding area  23 . 
     Here, before explaining a reason why the above-mentioned operation is performed by the backlight controller  16 , one example of the LPF  35  is explained with reference to  FIG. 9 . The LPF  35  is supplied at an input terminal  35   a  with maximum values of luminous of respective areas  23  output from the all-area maximum value storage  34 . Each of the maximum values of luminous supplied to this input terminal  35   a  is supplied to a multiplier  35   b , multiplied by a coefficient K 1  held in a coefficient K 1  holder  35   c  and supplied to an input terminal of an adder  35   d.    
     Further, the LPF  35  is supplied at an input terminal  35   e  with emitted light amount control values for the light sources  24  per area  23  stored in the control value storage  36 . Each of the emitted light amount control values supplied to the input terminal  35   e  is supplied to a multiplier  35   f , multiplied by a coefficient K 2  held in a coefficient K 2  holder  35   g  and then supplied to the other input terminal of the adder  35   d.    
     Then, the adder  35   d  adds the luminous value output from the multiplier  35   b  and the emitted light amount control value output from the multiplier  35   f  of the same area  23   a  and outputs the resultant value as a new emitted light amount control value to the control value storage  36  via an output terminal  35   h . Therefore, the control value storage  36  writes and holds the emitted light amount control value supplied from the LPF  35 , in the emitted light amount control value storage  36   c  of the corresponding area  23 . 
     The operation of the LPF  35  is described by way of a specific example of the one given area  23 . It is assumed that the coefficient K 1  is 0.4 and the coefficient K 2  is 0.6. When the value supplied to the input terminal  35   a  is changed from 0 to 1, its input value is multiplied by 0.4. Then, if an emitted light amount control value supplied from a corresponding emitted light amount control value storage  36   c  of the control value storage  36  to the input terminal  35   e  is 0, an output from the adder  35   d  becomes 0.4, which is stored in the corresponding emitted light amount control value storage  36   c  of the control value storage  36  as a new emitted light amount control value. 
     In the next same area  23 , a value 1 supplied to the input terminal  35   a  is multiplied by 0.4 at the multiplier  35   b . At this time, an emitted light amount control value supplied from the corresponding emitted light amount control value storage  36   c  of the control value storage  36  to the input terminal  35   e  is 0.4 stored previously. Therefore, 0.4 output from the multiplier  35   b  and 0.24 obtained by multiplying 0.4 supplied to the input terminal  35   e  by 0.6 at the multiplier  35   f  are added at the adder  35   d  to result in 0.64. Then, this value of 0.64 is stored in the corresponding emitted light amount control value storage  36   c  of the control value storage  36  as a new emitted light amount control value. 
     Through repetition of such an operation, as denoted by the solid line A in (a) of  FIG. 10 , when the value supplied to the input terminal  35   a  is changed from 0 to 1, a value output from the LPF  35  becomes a value that shows gradual increase as denoted by the dotted line B in (a) of  FIG. 10 , that is, a value subjected to the filtering processing in the time axis direction. 
     Likewise, if the value supplied to the input terminal  35   a  is changed from 1 to 0, an output value from the LPF  35  shows gradual decrease. 
     Here, (a) in  FIG. 11  illustrates a right-eye image displayed on the liquid crystal display panel  17  and (b) in  FIG. 11  illustrates light emission of each of the light sources  24  that make up the backlight  19  corresponding to this right-eye image. (a) in  FIG. 12  illustrates a left-eye image displayed on the liquid crystal display panel  17  and (b) in  FIG. 12  illustrates light emission of each of the light sources  24  that make up the backlight  19  corresponding to this left-eye image. 
     That is, in both the right- and left-eye images, the local dimming technique is applied so that in a high-luminous (brighter) part (indicated in white in (b) of  FIGS. 11 and 12 ), the emitted light amount of a corresponding light source  24  is great (light is bright) and in a low-luminous (darker) part (indicated in black in (b) of  FIGS. 11 and 12 ), the emitted light amount of a corresponding light source  24  is small (light is dark). 
     Here, as described above, the right- and left-eye images in the stereoscopic vision have parallax corresponding to the distance between the eyes. In other words, as is clear from comparison between the right-eye image as illustrated in (a) of  FIG. 11  and the left-eye image as illustrated in (a) of  FIG. 12 , the position of a subject existing in the vicinity (white circle in (a) of  FIGS. 11 and 12 ) is shifted left in the right-eye image and shifted right in the left-eye image, though the position of a subject far away (house in (a) of  FIGS. 11 and 12 ) is not much different between the right- and left-eye images. 
     Therefore, when attention is paid to a given area  23   a  in the right-eye image illustrated in (a) of  FIG. 11 , it is found that there exists a high-luminous subject indicated by the while circle in the right-eye image, but the high-luminous subject indicated by white circle does not exist in the left-eye image. This means that with reference to the backlight  19 , the light source  24  corresponding to the given area  23   a  is controlled to emit a greater amount of light (be brighter) when the right-eye image is displayed and to emit a smaller amount of light (be darker) when the left-eye image is displayed. 
     Then, since in the stereoscopic vision, the right- and left-eye images are displayed alternately, the light source  24  corresponding to the above-mentioned given area  23   a  is controlled to emit a large amount of light and a small amount of light alternately. 
     Therefore, it is assumed that when the above-mentioned serial processing module  14  outputs the right- and left-eye image signals alternately, in the above-mentioned given area  23   a , a maximum value of luminous obtained from the right-eye image and a maximum value of luminous obtained from the left-eye image are supplied simply alternately to the LPF  35 . 
     Then, the values of luminous supplied to the input terminal  35   a  of the LPF  35  become greatly different, as denoted by the solid line A in (c) of  FIG. 10 , between when the right-eye image is displayed and when the left-eye image is displayed. Then, in the LPF  35 , as described above, the input value is subjected to the filtering processing in the time axis direction and output as an output value that changes gradually in the time axis direction. 
     Therefore, the output value from the LPF  35  is, as denoted by the dotted line B in (c) of  FIG. 10 , reduced to be about a half of the input value and this output value of the LPF  35  becomes an emitted light amount control value for controlling the emitted light amount of the corresponding light source  24  in the above-mentioned given area  23   a . Hence, the emitted light amount of the light source  24  is not increased enough and the user feels that the display image in the given area  23   a  is dark. 
     Then, like the above-mentioned backlight controller  16 , in each of the plural areas  23  (j×k areas) divided from the panel surface of the liquid crystal display panel  17 , a substantially greater value of a maximum value of luminous in the right-eye image and a maximum value of luminous in the left-eye image is selected and the selected luminous value is output to the LPF  35 . 
     This is because, as illustrated in (a) of  FIG. 13 , an image is generated by selecting an image of higher luminous in each area  23  out of the right-eye image as illustrated in (a) of  FIG. 11  and the left-eye image as illustrated in (a) of  FIG. 12 . Then, as illustrated in (b) of  FIG. 13 , the emitted light amount of each light source  24  of the backlight  19  is controlled corresponding to the image illustrated in (a) of  FIG. 13 . 
     Thus, since a substantially greater value of the maximum value of luminous in the right-eye image and the maximum value of luminous in the left-eye image is supplied to the LPF  35 , even if the maximum value of luminous in the right-eye image and the maximum value of luminous in the left-eye image are greatly different from each other as denoted by the dotted line A in (b) of  FIG. 10  in the above-mentioned predetermined area  23   a , the luminous value input to the LPF  35  becomes the greater luminous value as denoted by the solid line B in (b) of  FIG. 10 . 
     With this structure, the output value of the LPF  35  is prevented from being reduced to the input value or less as denoted by the dotted line C in (b) of  FIG. 10  even when the filtering processing is performed in the time axis direction, and the emitted light amount of each light source  24  at the position corresponding to the above-mentioned predetermined area  23   a  can be sufficiently larger and it becomes possible to prevent the user from feeling darkness of the display image in the predetermined area  23   a.    
       FIG. 14  illustrates a modification of the stereoscopic image display device  11  explained in this embodiment. In  FIG. 14 , the same parts as those in  FIG. 1  are denoted by the same reference numbers for explanation. The right- and left-eye image signals output alternately from the serial processing module  14  are supplied to a double-frame processing module  38 . This double-frame processing module  38  has a function to receive right- and left-eye image signals alternately and output two right-eye image signals and two left-eye image signals at double speed. 
     In other words, it is assumed that the above-mentioned input terminal  12  receives the right-eye image signals R 1 , R 2 , . . . , at the frame period of 1/60 second as illustrated in (a) of  FIG. 15  and the above-mentioned input terminal  13  receives the left-eye image signals L 1 , L 2 , . . . , at the frame period of 1/60 second as illustrated in (b) of  FIG. 15 . 
     Then, the serial processing module  14  outputs, as illustrated in (c) of  FIG. 15 , right- and left-eye image signals alternately at the frame period of 1/120 second, and the double-frame processing module  38  outputs, as illustrated in (d) of  FIG. 15 , two right-eye image signals and two left-eye image signals alternately at the frame period of 1/240 second. 
     In (e), (f) and (g) of  FIG. 15 , the vertical axis denotes the height direction of the screen. The two right-eye image signals and two left-eye image signals output alternately from the double-frame processing module  38  at the frame period of 1/240 second are, as illustrated in (e) of  FIG. 15 , sequentially written per frame in the liquid crystal display panel  17 . 
     In this case, writing of image signals for each frame into the liquid crystal display panel  17  is performed sequentially line by line from the upper side to the lower side of the screen. Therefore, writing to the undermost horizontal line is performed just before writing to a next frame is started. Here, since liquid crystal is a hold type device, it holds the same signals until the next writing. 
     The backlight  19  is turned off per frame as illustrated in (f) of  FIG. 15 . In this case, the plural light sources  24  that make up the backlight  19  are controlled to be turned on and off in each of the areas  23  in synchronization with writing of the image signals in the liquid crystal display panel  17 . 
     Then, with use of the backlight  19  controlled as illustrated in (f) of  FIG. 15 , the display image as illustrated in (g) of  FIG. 15  obtained by illuminating the liquid crystal display panel  17  to which image signals are written as illustrated in (e) of  FIG. 15 , that is, an image with a one-frame black screen interposed between each right-eye image and each left-eye image displayed alternately, is visually recognized by the user wearing the stereoscopic glasses  21 . 
     In this case, the above-mentioned glasses controller  20  outputs, as illustrated in (h) of  FIG. 15 , a right-eye shutter control signal to open the right-eye shutter of the stereoscopic glasses  21  at the low level occurring when the black screen and its following right-eye image are displayed and to close the right-eye shutter of the stereoscopic glasses  21  at the high level occurring when the black screen and its following left-eye image are displayed. 
     In addition, the glasses controller  20  outputs, as illustrated in (i) of  FIG. 15 , a left-eye shutter control signal to open the left-eye shutter of the stereoscopic glasses  21  at the low level occurring when the black screen and its following left-eye image are displayed and to close the left-eye shutter of the stereoscopic glasses  21  at the high level occurring when the black screen and its following right-eye image are displayed. 
     When the operation explained with reference to  FIG. 15  is performed, the maximum values of luminous stored in the right-eye maximum value storage area  34   c   1  and the left-eye maximum value storage area  34   c   2  of each of the maximum value storages  34   c  that make up the above-mentioned all-area maximum value storage  34  are updated every three frames. 
     Further,  FIG. 16  illustrates another operation example of the modification of the stereoscopic image display device  11  illustrated in  FIG. 14 . That is, the above-mentioned input terminal  12  receives right-eye image signals R 1 , R 2 , . . . , at the frame period of 1/60 second as illustrated in (a) of  FIG. 16  and the above-mentioned input terminal  13  receives left-eye image signals L 1 , L 2 , . . . , at the frame period of 1/60 second as illustrated in (b) of  FIG. 16 . 
     Then, the serial processing module  14  outputs, as illustrated in (c) of  FIG. 16 , right- and left-eye image signals alternately at the frame period of 1/120 second and the double-frame processing module  38  outputs, as illustrated in (d) of  FIG. 16 , right- and left-eye image signals alternately with a black screen interposed therebetween at the frame period of 1/240 second. 
     In (e), (f) and (g) of  FIG. 16 , the vertical axis denotes the height direction of the screen. The right- and left-eye image signals alternately output from the double-frame processing module  38  with the black screen interposed therebetween at the frame period of 1/240 second are written in the liquid crystal display panel  17  on a per-frame basis, as illustrated in (e) of  FIG. 16 . 
     In this case, writing of image signals for each frame into the liquid crystal display panel  17  is sequentially performed horizontal line by line from the upper side to the lower side of the screen. Therefore, wiring to the undermost horizontal line is performed just before writing to the next frame is started. Here, the liquid crystal is a hold type device and therefore, holds the same signals until the next writing. 
     The backlight  19  is turned off on a per-frame basis, as illustrated in (f) of  FIG. 16 . In this case, the plural light sources  24  that make up the backlight  19  are controlled to turn on and off corresponding to the respective areas  23 , in synchronization with writing of image signals to the liquid crystal display panel  17 . 
     Then, with the backlight  19  controlled as illustrated in (f) of  FIG. 16 , a display image illustrated in (g) of  FIG. 16  obtained with illumination of the liquid crystal display panel  17  in which image signals are written as illustrated in (e) of  FIG. 16 , that is, an image in which a black screen for one frame is interposed between right- and left-eye images that are displayed alternately, is visually recognized by the user wearing the stereoscopic glasses  21 . 
     In this case, as illustrated in (h) of  FIG. 16 , the above-mentioned glasses controller  20  outputs a right-eye shutter control signal to open the right-eye shutter of the stereoscopic glasses  21  at the low level occurring just when the black screen and its following right-eye image are displayed and to close the right-eye shutter of the stereoscopic glasses  21  at the high level occurring just when the black screen and its following left-eye image are displayed. 
     In addition, as illustrated in (i) of  FIG. 16 , the glasses controller  20  outputs a left-eye shutter control signal to open the left-eye shutter of the stereoscopic glasses  21  at the low level occurring just when the black screen and its following left-eye image are displayed and to close the left-eye shutter of the stereoscopic glasses  21  at the high level occurring just when the black screen and its following right-eye image are displayed. 
     As explained with reference to (g) of  FIG. 15  and (g) of  FIG. 16 , as the black screen is interposed between the right- and left-eye images that are displayed alternately, it becomes possible to make the user visually recognize high-contract distinct stereoscopic images. 
     Further, in the above-mentioned embodiments, the image is displayed with use of the liquid crystal display panel  17 . However, the image display panel is not limited to a liquid crystal type, and the present invention may be applied to a wide range of panels as long as they are for displaying images with use of illumination light from the backlight  19 . 
     The various modules of the systems described herein can be implemented as software applications, hardware and/or software modules, or components on one or more computers, such as servers. While the various modules are illustrated separately, they may share some or all of the same underlying logic or code. 
     While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.