Abstract:
The object of the invention is elimination of an occurrence of instantaneous light in the center part of a display, a border between the upper half and the lower half of the display. 
     An scanning method of the display, dividing the display panel to a first filed and a second filed, starts a counter therein, synchronized with the timing of driving a first row electrode of the first filed thereof, and drives a first row electrode of the second filed thereof, every time the counter value changes.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a scanning method of display panel and a display unit, especially a scanning method of display panel and a display unit for dividing a display panel to plurals of fields. 
     The document 1 discloses the conventional scanning method and the conventional display unit. According to the conventional technology of the document 1, the display panel having n (n: positive integer of multiples of two) of scanning lines is divided to the upper half having scanning lines from 1st to (n/2)th and the lower half from (n/2+1)th to (n)th. The disclosed method is that scanning of the upper half is done in the order of 1st, 2nd, - - - , (n/2)th line, scanning of the lower half is done in the order of (n/2+1)th, (n/2+2)th, - - - , (n)th. 
     The Document 1: Japanese Patent Application Laid-Open Number 2003-302937 
     However, according to the scanning method of the document 1, when there is some difference of scanning timing between the upper half and the lower half, the upper (n/2)th scanning line and the lower (n/2+1)th scanning line, respectively located next to each other, might be scanned at the same time. 
     Furthermore, the embodiments of the document 1 discloses the method that the scanning lines are divided to the upper half and the lower half, and the upper half line and the lower half line are scanned in the alternating order from every two lines equivalently located across the central axis of the panel. Although, in this case, the upper (n/2)th line and the lower (n/2+1)th line, located next to each other, must be scanned at the same time. 
     When the scanning lines next to each other are scanned at the same time, the scanning can be seen as if a only one line were scanned, and then there is a problem that a stronger light is observed than in other scanning lines. 
     Consequently, according to the conventional scanning method, there is a problem that every time one frame is displayed, the stronger light occurs in a moment at the center of the panel, the border between the upper half and the lower half. 
     SUMMARY OF THE INVENTION 
     According to a embodiment of the present invention, the scanning method of display panel is that the frame is displayed, dividing the display panel to the first field and the second field. A counter thereof is started, synchronized with the timing of driving the first row electrode of the first field thereof, and the first electrode of the second field is driven every time the counter value changes. 
     A display unit according to a embodiment of the present invention consists of a display panel, a first row driver, a column driver, a second row driver, a column driver, a first controller, and a second controller. The display panel is divided to the first and the second field. The first row driver drives the row electrode of the first field. The first column driver drives the column electrode of the first field. The second row driver drives the row electrode of the second field. The second column driver drives the column electrode of the abovementioned second field. The first controller controls the first row driver and the first column driver, and generates a sync signal, synchronized with driving one of the row electrodes of the first field. The second controller controls the second row driver and the second column driver, and starts driving the electrodes of the second field, synchronized with the sync signal thereof. 
     The scanning method of display panel and the display unit, according to the present invention, eliminates the instantaneous stronger lights at the center of the display panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a part of the display unit of the present invention. 
         FIG. 2  is the view of a display unit according to a first embodiment of the present invention. 
         FIG. 3  is a timing chart of the scan direction  1 . 
         FIG. 4  is a block diagram of a display unit according to the second embodiment of the present invention. 
         FIG. 5  is a timing chart of the scan direction  1 . 
         FIG. 6  is a timing chart of the scan direction  2 . 
         FIG. 7  is a block diagram of a display unit according to the third embodiment of the present invention. 
         FIG. 8  is a timing chart showing the scan method of a display unit according to the third embodiment of the present invention. 
         FIG. 9  is a block diagram of a display unit according to other embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A dual scan driving, used in the scanning method of display panel according to the present invention, will be explained, referring to  FIG. 1 . The dual scan driving is that the row electrode is divided to two groups and each group is driven independently. By way of the explanation, the display panel in  FIG. 1  is divided to two groups, however, it is obvious that dividing to three groups is applicable to the present invention. 
       FIG. 1  is a view of a block diagram of a part of a display unit in accordance with the present invention. The display unit includes an organic EL display panel  100 , a row driver  110 , and a column driver  120 , 130 . The row driver  110  has n (n: integers) of row electrodes. The column driver  120 , 130  drive m (m: integers) of column electrodes, respectively. The organic EL display panel  100  has a matrix structure of row electrodes and column electrodes and organic EL devices is formed at the cross points of the matrix. 
     In the dual scan driving, according to the present invention, the organic EL is divided to the upper field  101 , consisting of from the 1st electrode to the (n/2)th electrode, and the lower field  102 , consisting of from the (n/2+1)th electrode to the (n/2+2)th electrode. The abovementioned dual scan driving, according to the present invention, includes two scanning directions. The scanning direction  1  is that the row electrodes of the upper field  101  are scanned in the order from 1st, 2nd, - - - to (n/2)th and the row electrodes of the lower field  102  are scanned in the order of (n/2+1)th, (n/2+2)th, - - - , (n)th. In contrast, the scanning direction  2  is that the row electrodes of the upper field  101  are scanned in the order of (n/2)th, (n/2−1)th, - - - , 1st and the row electrodes of the lower field  102  are scanned in the order of (n)th (n−1)th, - - - , (n/2+1)th. 
     First Embodiment 
     The first embodiment of the invention will be explained as below, referring to the drawing.  FIG. 2  is a view of a display unit in accordance with a first embodiment of the present invention. The display unit includes an organic EL display panel  200 , a first row driver  210 , a second driver  220 , a first column driver  230 , a second column driver  240 , a first controller  250 , a second controller  260 . 
     The organic EL display panel  200  is divided to the upper field  201  and the lower field  202 . The first row driver  210  drives row electrodes of the upper field  201  of the organic EL display panel  200 , and the second row driver  220  drives row electrodes of the lower field  202  of the organic EL display panel  200 . The first column driver  230  derives column electrodes of the upper field  201  of the organic EL display panel  200 , and the second column driver  240  derives column electrodes of the upper filed  202  of the organic EL display panel  200 . 
     The first controller  250  connects the first row driver  210 , the first column driver  230  and the second controller  260 , together. The first controller  250  inputs a scan direction signal  270  and outputs a first control signal  251 , a second control signal  252  and a sync signal  253 . The first control signal  251  controls the first row driver  210 . The second control signal  252  controls the first column driver  230 . The sync signal  253  adjusts the synchronization of the second controller  260 . 
     The second controller  260  connects the second row driver  220 , the second column driver  240  and the first controller  250 , together. The second controller  260  inputs a scan direction signal  270  and a sync signal  253 , and outputs a third control signal  261  and a forth control signal  262 . The third control signal  261  controls the second row driver  220 . The forth control signal  262  controls the second column driver  240 . 
     A scanning method of display panel, according to the first embodiment of the present invention, will be explained as below, referring to the drawing.  FIG. 3  is view of a timing chart of the scanning method of display panel in accordance with the first embodiment. The timing chart of  FIG. 3  is based on the direction  1 . 
     The first row driver drives electrodes in the order from 1st, 2nd, - - - , (n/2−1)th, (n/2)th. The driving method thereof will be explained specifically as below. Firstly, the first row driver  210  drives the first electrode and outputs the sync signal  253 , as an one-shot pulse, at the same time. The first row driver  210  increments the counter value thereof one by one, detecting the rising edge of the sync signal  253 . Where, the counter value thereof is incremented in the order of 1, 2, - - - , m−1, m. In addition, the counter value also can be decremented in the order of m, m−1, - - - , 2, 1. Secondly, the first row driver drives the second row electrode, detecting change of the counter value thereof from 1 to 2. Further, the first row driver  210  repeats the aforementioned driving sequence. 
     At the same time, the second row driver  220  drives the row electrodes in the order from (n/2+1)th, (n/2+2)th, - - - , (n−1)th, (n)th. The driving method thereof will be explained as below. The second row driver  220  increments the counter value thereof by one, detecting the rising edge of the sync signal  253  and outputs derives the (n/2+1)th electrode, at the same time. Where, the counter value thereof is incremented in the order of 1, 2, - - - , (m−1)th. In addition, the counter value can be decremented in the order of m, m−1, - - - , 2, 1. Secondly, the second driver  220  drives the (n/2+2)th electrode, detecting a change of the counter value from 1 to 2. Further, the second row driver  220  repeats the aforementioned driving sequence. 
     In the scanning method of display panel and the display unit, according to the first embodiment of the present invention, the changing timing of each electrode of the upper and lower field of the organic EL display matches each other. Then, the overlapping can be avoided between scan timing of the (n/2)th row electrode of the upper field and the (n/2+1)th row electrode of the lower field. (refer to the line of  300  in  FIG. 3 ). Consequently, the scanning method of display panel and the display unit, according to the first embodiment of the present invention, can eliminates the instantaneous stronger lights at the center of organic EL display panels. 
     The direction  1  (from the top to the bottom) is explained as before, though, it is obvious that the fist embodiment of the present invention is applicable to the scanning direction  2  (from the bottom to the top). 
     Second Embodiment 
     A display unit, according to the second embodiment of the invention, will be explained as below, referring to the drawing. Where, the identical components to the components of the first embodiment are labeled with the same reference numbers, and the dual explanations are neglected.  FIG. 4  is a display unit, according to the second embodiment of the invention. The display unit includes the organic EL display unit  200 , the first row driver  210 , the second row driver  220 , the first column driver  230 , the second column driver  240 , the controller  250 , a phase adjuster  410 . A second controller  400  connects the second row driver  220 , the column driver  240 , the first controller  250 , and the phase adjuster  410 , together. The second controller  400  inputs the scan direction signal  270 , the sync signal  253  and starting phase signal  411 , and outputs the fifth control signal  401  and the sixth control signal  402 . 
     The fifth control signal  401  controls the second row driver  220 . The sixth control signal  402  controls the second column driver. 
     The phase adjuster  410  connects the second controller  400  and inputs the scan direction signal  270  and outputs the starting phase signal  411 . The starting phase signal  411  adjusts the phase of the row electrodes of the lower field  202  of the organic EL display panel. The phase adjuster  410  judges the scanning direction thereof by the scanning direction signal  270 . In the case of the scanning direction  1  (from the bottom to the top), the phase adjuster  410  outputs the one-clock-behind phase value to the second controller as the starting phase signal  411 . Further, in the case of the scanning direction  2  (from the top to the bottom), the phase adjuster  410  outputs the one-clock-beyond phase value to the second controller as the starting phase signal  411 . 
     At the same time, the second row driver  400  drives the row electrodes in the order of (n/2+1)th, (n/2+2)th, - - - , (n−1)th, (n)th. The driving method thereof will be explained as below. The second row driver  400  increments the counter value thereof by one, detecting the rising edge of the starting phase signal  411  and outputs derives the (n/2+1)th electrode, at the same time. Where, the counter value thereof is incremented in the order of 1, 2, - - - , (m−1)th. In addition, the counter value can be decremented in the order of m, m−1, - - - , 2, 1. Secondly, the second driver  400  drives the (n/2+2)th electrode, detecting a change of the counter value from 1 to 2. Further, the second row driver  400  repeats the aforementioned driving sequence. 
     Secondly, the scanning method of display panel of the scanning direction  2 , according to the second embodiment of the present invention, will be explained, referring to  FIG. 6 . The first row driver  210  drives the row electrodes in the order of (n/2)th, (n/2−1)th, - - - , 2nd, 1st. The driving method will be explained specifically as below. 
     First, the first row driver  210  drives the (n/2)th row electrode, and outputs an one-shot pulse, as the sync signal  253 , at the same time. The first row driver  210  increments the counter value thereof one by one, detecting the rising edge of the sync signal  253 . Where, the counter value thereof is incremented in the order of 1, 2, - - - , m−1, m. In addition, the counter value also can be decremented in the order of m, m−1, - - - , 2, 1. Secondly, the first row driver  210  drives the (n/2−1)th row electrode, detecting a change of the counter value thereof from 1 to 2. Further, the first row driver  210  repeats the aforementioned driving sequence. 
     Where, the phase adjuster  410  outputs an one-shot pulse, as the starting phase signal  411 . 
     At the same time, the second row driver  400  drives the row electrodes in the order of (n)th, (n−1)th, - - - , (n/2+2)th, (n/2+1)th. The driving method thereof will be explained specifically as below. The second row driver  400  increments the counter value thereof by one, detecting the rising edge of the starting phase signal  411  and outputs derives the (n)th electrode, at the same time. Where, the counter value thereof is incremented in the order of 1, 2, - - - , (m−1)th. In addition, the counter value also can be decremented in the order of m, m−1, - - - , 2, 1. Secondly, the second driver  400  drives the (n−1)th electrode, detecting a change of the counter value from 1 to 2. Further, the second row driver  400  repeats the aforementioned driving sequence. 
     As explained before, with the scanning method of display panel in accordance with the second embodiment of the invention, the phase value, one-clock-behind the phase of the first controller  250 , is outputted to the second controller  400 , as the starting phase signal  411 , in the case of scanning direction  1  (from the top to the bottom). Then, in the case of the scan direction  1 , the (n/2)th row electrode of the lower field is fired when the (n/2) the electrode of the upper field  201  is fired. Consequently, in the case of the scan direction  1 , there is one-clock time-difference between the firings of the (n/2)th electrode of the upper field and the (n/2+1)th row electrode of the lower field, located at the center of the display panel. 
     In similarity, the phase value, one-clock-beyond the phase of the first controller  250 , is outputted to the second controller  400 , as the starting phase signal  411 , in the case of scanning direction  2  (from the bottom to the top). Then, in the case of the scan direction  2 , the 2nd row electrode of the lower field is fired when the (n/2+1)th electrode of the upper field  201  is fired. Consequently, in the case of the scan direction  2 , there is one-clock time-difference between the firings of the (n/2)th electrode of the upper field and the (n/2+1)th row electrode of the lower field, located at the center of the display panel. 
     The scanning method and the display unit, according to the second embodiment of the invention, can reduce the slight time difference between the firings of the (n/2)th row electrode of the upper field and the (n/2+1)th electrode of the lower field, caused by skews between the clocks of the first controller and the second controller and variations in the wiring delay time from each controller to each row driver (refer to the line of  500  of  FIG. 5  and the line of  600  of  FIG. 6 ). 
     In addition, the scanning method and the display unit, according to the second embodiment of the invention, delays the phase of the lower field by one clock in the case of direction  2 , in advance. Subsequently the occurrence of instantaneous stronger lights can be decreased, even if the phase of the upper field is delayed by one clock. Further, in the case of the direction  2 , the phase value of the lower field is proceeded by one clock, then the occurrence of instantaneous stronger lights can be decreased, even if the phase of the upper field is delayed by one clock. 
     The Third Embodiment 
     The display unit, according to the third embodiment of the invention, will be explained, referring to the drawings. Where, the overlapped explanations are neglected, labeling the identical components to the components of the first embodiment or the second embodiment with the same reference numbers.  FIG. 7  is a view of the display unit in accordance with the third embodiment of the invention. The display consists of the organic EL display panel  200 , the first row driver  210 , the second row driver  220 , the first  220 , the first column driver  230 , the second column driver  240 , the first controller  700 , the second controller  710 , and the phase adjuster  410 . 
     The first controller  700  connects the first row driver, the column driver  230  and the second controller  710 . The first controller  700  inputs the scan direction  270  and the external-display setting signal  720 . Where, the external-display setting signal  720  includes the information of directions to change display mode, such as on-off directions to display images on the panel, directions to change the size of the display and directions to start or stop the screen saver. In addition, the first controller  700  outputs the seventh control signal  701 , the eighth control signal  702 , the sync signal  703  and the display control signal  704 . The seventh control signal  701  controls the first row driver  210 . The eighth control signal  702  controls the first column driver  230 . The sync signal  703  adjusts the synchronization of the second controller  710 . The display control signal  704  indicates the display mode information. 
     The second controller  710  connects the second row driver  220 , the second column driver  240 , the first controller  700  and the phase adjuster  410 . The second controller  710  inputs the scan direction signal  270 , the sync signal  703  and the display control signal  704 , and outputs the ninth control signal  711  and the tenth control signal  712 . The ninth control signal controls the second row driver  220 . The tenth control signal  712  controls the second column driver  220 . 
     The scanning method of display panel, according to the third embodiment of the invention, will be explained as below, referring to the drawings. 
       FIG. 8  is a view of a timing chart of the scanning method of display panel in accordance with the third embodiment of the invention. Where, in the case of the scan direction  1 , the period while all row electrodes is scanned in the order from 1st to (n/2)th is called a frame. When the display control signal  704  is inputted during the frame  1  thereof, the upper and the lower field of the display panel maintains the current information of display. Then the upper field updates the information of display to the new one, synchronized with the rising edge of the sync signal  703 . Further, the lower field updates the information of display to the new one, detecting the rising edge of the starting phase signal  411  and synchronized with changing of the counter value from m to 1. 
     The scanning method and the display unit, according to the third embodiment of the invention, can reduce slight overlapping of firing time between (n/2)th electrode of the upper field and the (n/2+1)th electrode of the lower field, as the second embodiment (refer to the component  800  of  FIG. 8 ). Subsequently, said scanning method and the display unit, according to the third embodiment of the invention, can reduce the occurrence of the stronger light caused by said slight overlapping of firing time. 
     Further, the scanning method of display panel and the scan unit, in according to the third embodiment of the invention, can get synchronization of every frame between the upper field and lower field, then the same operation over the whole display panel can be done even while the display mode is changed. In addition, the direction  1  (from the top to the bottom) is explained for the third embodiment of the invention. Although, it is obvious that the scan direction  2  is applicable to the third embodiment. 
     The dual scanning method dividing the display panel to two fields and the display unit using the above dual scanning method is explained, according to the first, the second and the third embodiment of the invention. However, the display in accordance with the embodiments of the invention is applicable to the case of dividing the panel to three fields, as showed in  FIG. 9 . In this case, the first controller  900  outputs the sync signal and other controllers are controlled by the sync signal thereof. In addition, according to the first, the second and the third embodiment of the invention, the display panel is described as the organic EL display panels. However, it is obvious that the thoughts of the scanning method and the display unit in accordance with the first, the second and the third embodiment of the invention can be applied to the liquid crystal display unit. 
     This is a counterpart of and claims priority to Japanese patent application Serial Number 223074/2004, filed on Jul. 30, 2004, the subject matter of which is incorporated herein by reference.