Abstract:
Exemplary backlight driving method and display device are provided. The display device includes a light source array. The light source array includes a first group of light-emitting rows and a second group of light-emitting rows. The backlight driving method includes the steps of: firstly, receiving a gate driving frequency of the display device; subsequently, generating a backlight driving frequency according to the gate driving frequency; and afterwards, sequentially providing a first row driving voltage to the first group of light-emitting rows in a first time period and sequentially providing a second row driving voltage to the second group of light-emitting rows in a second time period, according to the backlight driving frequency. The first time period and the second time period have different phases from each other, and the gate driving frequency is different from the backlight driving frequency.

Description:
BACKGROUND 
     1. Technical Field 
     The present invention generally relates to display technology fields and, particularly to a backlight driving method and a display device. 
     2. Description of the Related Art 
     Nowadays, display panels of non-emissive display devices such as liquid crystal display devices are non-emissive and thus backlight modules are necessarily required for providing backlight illumination for such display panels. Light sources suitable for the backlight modules can be primarily classified into cold cathode fluorescent lamps (CCFLs), light-emitting diodes (LEDs) and other electroluminescence devices. 
     However, in the prior art, a driving frequency for backlight would interfere with images displayed on a relevant liquid crystal display screen. For example, when the backlight driving frequency (i.e., generally lamp frequency) approximately is close to a multiple of a video refreshing frequency, the display screen would appear black lines or black bands moving along a difference between the frequencies, causing a waving noise or visual noise. 
     BRIEF SUMMARY 
     Accordingly, the present invention is directed to a backlight driving method, can effectively relieve the waving noise or visual noise and improve the image quality. 
     More specifically, a backlight driving method in accordance with an embodiment of the present invention is adapted to a display device. Herein, the display device includes a light source array. The light source array includes a first group of light-emitting rows and a second group of light-emitting rows. In the embodiment, the backlight driving method includes following steps of: firstly, receiving a gate driving frequency of the display device; subsequently, generating a backlight driving frequency according to the gate driving frequency; and afterwards, sequentially providing a first row driving voltage to the first group of light-emitting rows in a first time period and sequentially providing a second row driving voltage to the second group of light-emitting rows in a second time period both according to the backlight driving frequency. The first time period and the second time period have different phases from each other, and the gate driving frequency is different from the backlight driving frequency. 
     In one embodiment, the first time period and the second time period are in a same frame period. Moreover, the step of sequentially providing a first row driving voltage to the first group of light-emitting rows in a first time period and sequentially providing a second row driving voltage to the second group of light-emitting rows in a second time period includes sequentially providing the first row driving voltage and the second row driving voltage to the respective first group of light-emitting rows and second group of light-emitting rows in an alternate manner. Even more, a scanning direction of sequentially providing the first row driving voltage to the first group of light-emitting rows is same as or different from a scanning direction of sequentially providing the second row driving voltage to the second group of light-emitting rows. 
     In an alternative embodiment, the first time period and the second time period respectively are in different frame periods. Moreover, the step of sequentially providing a first row driving voltage to the first group of light-emitting rows in a first time period and sequentially providing a second row driving voltage to the second group of light-emitting rows in a second time period includes sequentially providing the first row driving voltage and the second row driving voltage to the respective first group of light-emitting rows and second group of light-emitting rows in an alternate manner. Even more, a scanning direction of sequentially providing the first row driving voltage to the first group of light-emitting rows is same as or different from a scanning direction of sequentially providing the second row driving voltage to the second group of light-emitting rows. 
     A display device in accordance with an embodiment of the present invention includes a light source array, a column driver circuit and a row driver circuit. The light source array includes a first group of light-emitting rows and a second group of light-emitting rows. The column driver circuit is electrically coupled to the light source array and for providing a column driving voltage to the light source array. The row driver circuit is electrically coupled to the light source array. The row driver circuit further is for receiving a gate driving frequency of the display device, generating a backlight driving frequency according to the gate driving frequency, and sequentially providing a first row driving voltage to the first group of light-emitting rows in a first time period and sequentially providing a second row driving voltage to the second group of light-emitting rows in a second time period both according to the backlight driving frequency. The first time period and the second time period have different phases from each other, and the gate driving frequency is different from the backlight driving frequency. 
     In one embodiment, the light source array is an organic light source array or a field emission backlight source array. 
     In summary, the above-mentioned embodiments of the present invention employ a multi-phase (e.g., 2-phase) scanning scheme to drive the light source array of a backlight module and make the backlight driving frequency be different from the gate driving frequency, so that breaking down a constant frequency difference between the gate driving frequency and the backlight driving frequency associated with the prior art which would cause the fan effect (i.e., generally waving noise or visual noise). Accordingly, the image quality of display device is improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which: 
         FIG. 1  shows a schematic circuit block diagram of a backlight part of a display device in accordance with an embodiment of the present invention. 
         FIG. 2  shows a flowchart of a backlight driving method in accordance with an embodiment of the present invention. 
         FIG. 3  shows a schematic scanning order used by the backlight driving method of  FIG. 2  in a same frame period. 
         FIG. 4(   a ) shows another schematic scanning order used by the backlight driving method of  FIG. 2  in a same frame period. 
         FIG. 4(   b ) shows still another schematic scanning order used by the backlight driving method of  FIG. 2  in a same frame period. 
         FIG. 4(   c ) shows even still another schematic scanning order used by the backlight driving method of  FIG. 2  in a same frame period. 
         FIG. 5(   a ) shows a schematic scanning order used by the backlight driving method of  FIG. 2  in different frame periods. 
         FIG. 5(   b ) shows another schematic scanning order used by the backlight driving method of  FIG. 2  in different frame periods. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “up,” “bottom,” “row,” “column,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the present invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” and “coupled” and variations thereof herein are used broadly and encompass direct and indirect connections, and couplings. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
     Referring to  FIG. 1 , showing a schematic circuit block diagram of a backlight part of a display device in accordance with an embodiment of the present invention. As illustrated in  FIG. 1 , the display device  10  includes a column driver circuit  102 , a row driver circuit  104  and a light source array  106 . The column driver circuit  102  is electrically coupled to the light source array  106  through column driving lines D 1 ˜Dm, and the row driver circuit  104  is electrically coupled to the light source array  106  through row driving lines L 1 ˜L( 2 n); where m, n are positive integers. The light source array  106  is constituted by multiple light-emitting diodes and can be grouped into a first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) and a second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) cooperatively with the row driving lines L 1 ˜L( 2 n). 
     In a preferred embodiment of the present invention, the light-emitting diodes can be, for example small molecules organic light-emitting diodes (OLEDs) or polymer organic light-emitting diodes (PLEDs), but not to limit the present invention. Moreover, the light-emitting diodes can be, for example disposed in a backlight module (not shown), or directly formed on a pixel circuit substrate of the display device  100  by a particular process and whereby forming an in-cell light source array. 
     In a preferred embodiment of the present invention, the organic light source array  106  can be replaced by a field emission backlight source array. 
     In a preferred embodiment of the preset invention, as to the row driving lines L 1 ˜L( 2 n), each of the row driving lines L 1 ˜L( 2 n) has m number of light emitting diodes coupled therewith. As to the column driving lines D 1 ˜Dm, each of the column driving lines D 1 ˜Dm has 2n number of light emitting diodes coupled therewith. As far as a single light-emitting diode is concerned, when a voltage difference between a row driving voltage and a column driving voltage both applied to the light-emitting diode is enough to turn on the light-emitting diode, the light-emitting diode is lighted on. 
     Referring to  FIG. 1  and  FIG. 2  together,  FIG. 2  showing a flowchart of a backlight driving method in accordance with an embodiment of the present invention. The display device  100  (e.g., a microprocessor of the display device  100 ) would generate a gate driving frequency after the display device  100  is started. The gate driving frequency then is transmitted to the column driver circuit  102  and the row driver circuit  104  (Step S 202 ). It is understood to the skilled person in the art, the gate driving frequency generally is a scanning frequency of a display frame of the display device  100 . 
     In the illustrated embodiment, the column driver circuit  102  and the row driving circuit  104  would generate a backlight driving frequency (Step S 204 ) after they receive the gate driving frequency. It is understood to the skilled person in the art, the backlight driving frequency can be generated by the microprocessor of the display device  100  instead and then transmitted to both the column driver circuit  102  and the row driver circuit  104 . 
     In a preferred embodiment of the present invention, a rising edge and a falling edge of a period of the gate driving frequency respectively occur at same time points as a rising edge and a falling edge of corresponding periods of the backlight driving frequency. Moreover, the gate driving frequency is different from the backlight driving frequency. 
     Subsequently, the row driver circuit  104  sequentially provides a row driving voltage to the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) in a first time period and sequentially provides a row driving voltage to the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) in a second time period according to the backlight driving frequency, the first time period has a phase different from that of the second time period, while a frequency of the first time period is the same as that of the second time period (Step S 206 ). 
     Referring to  FIG. 3 , showing a scanning order used by the backlight driving method of  FIG. 2  in a same frame period. The row driver circuit  104  sequentially scans the light-emitting rows L 1 ˜L( 2 n) from up to bottom. Moreover, after the display device  100  of  FIG. 1  is started, the column driver circuit  102  continuously provides a column driving voltage to the light source array  106 . A scanning time interval for row by row is assumed to be 1 microsecond and an exemplary embodiment will be described below in detail. In particular, at the moment of 1 st  microsecond (belonging to the first time period), a row driving voltage provided from the row driver circuit  104  through the row driving line L 1  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 1  coupled to the row driving line L 1 . At the moment of 2 nd  microsecond (belonging to the second time period), a row driving voltage provided from the row driver circuit  104  through the row driving line L 2  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 2  coupled to the row driving line L 2 . At the moment of 3 rd  microsecond (belonging to the first time period), a row driving voltage provided from the row driver circuit  104  through the row driving line L 3  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 3  coupled to the row driving line L 3 . At the moment of 4 th  microsecond (belonging to the second time period), a row driving voltage provided from the row driver circuit  104  through the row driving line L 4  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 4  coupled to the row driving line L 4 . The rest light-emitting rows L 5 ˜L( 2 n) are lighted on in the same manner. In short, the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) are alternately lighted-on with the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n). 
     Referring to  FIG. 4(   a ), showing another scanning order used by the backlight driving method of  FIG. 2  in a same frame period. Herein, the first time period and the second time period both are in a frame period F 1 . A scanning time interval for row by row is assumed to be 1 microsecond and an exemplary embodiment will be described below in detail. In particular, at the moment of 1st microsecond (belonging to the first time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 1  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 1  coupled to the row driving line L 1 . At the moment of 2 nd  microsecond (belonging to the first time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 3  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 3  coupled to the row driving line L 3 . At the moment of (n+l)th microsecond (belonging to the second time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 2  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 2  coupled to the row driving line L 2 . At the moment of (n+2)th microsecond (belonging to the second time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 4  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 4  coupled to the row driving line L 4 . In this illustrated embodiment, after the light-emitting row L( 2 n− 1 ) of the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) is lighted on, the light-emitting row L 2  of the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) subsequently is lighted on. Moreover, a scanning direction of the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) being sequentially lighted on is the same as that of the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) being subsequently lighted on. 
     Referring to  FIG. 4(   b ), showing still another scanning order used by the backlight driving method of  FIG. 2  in a same frame period. Herein, the first time period and the second time period both are in a frame period F 1 . A scanning time interval for row by row is assumed to be 1 microsecond and an exemplary embodiment will be described below in detail. In particular, at the moment of 1st microsecond (belonging to the first time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 1  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 1  coupled to the row driving line L 1 . At the moment of 2 nd  microsecond (belonging to the first time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 3  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 3  coupled to the row driving line L 3 . At the moment of (n+1)th microsecond (belonging to the second time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L( 2 n) and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R( 2 n) coupled to the row driving line L( 2 n). At the moment of (n+2)th microsecond (belonging to the second time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L( 2 n− 2 ) and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R( 2 n− 2 ) coupled to the row driving line L( 2 n− 2 ). In this illustrated embodiment, after the light-emitting row L( 2 n− 1 ) of the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) is lighted on, the light-emitting row L( 2 n) of the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) subsequently is lighted on. Moreover, a scanning direction of the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) being sequentially lighted on is reverse to another scanning direction of the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) being sequentially lighted on. 
     Referring to  FIG. 4(   c ), showing even still another scanning order used by the backlight driving method of  FIG. 2  in a same frame period. Herein, the first time period and the second time period both are in a frame period F 1 . A scanning time interval for row by row is assumed to be 1 microsecond and an exemplary embodiment will be described below in detail. In particular, at the moment of 1st microsecond (belonging to the first time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 1  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 1  coupled to the row driving line L 1 . At the moment of 2 nd  microsecond (belonging to the first time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 3  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 3  coupled to the row driving line L 3 . At the moment of 1 st  microsecond (belonging to the second time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L( 2 n) and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R( 2 n) coupled to the row driving line L( 2 n). At the moment of 2 nd  microsecond (belonging to the second time period) in the frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L( 2 n−2) and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R( 2 n− 2 ) coupled to the row driving line L( 2 n− 2 ). In this illustrated embodiment, when the light-emitting row L( 2 n− 1 ) of the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) is lighted on, the light-emitting row L 2  of the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) is synchronously lighted on. Moreover, a scanning direction of the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) being sequentially lighted on is reverse to another scanning direction of the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) being sequentially lighted on. 
     Referring to  FIG. 5(   a ), showing a scanning order used by the backlight driving method of  FIG. 2  in different frame periods. Herein, the first time period is in a first frame period F 1 , and the second time period is in a second frame period F 2 . A scanning time interval for row by row is assumed to be 1 microsecond and an exemplary embodiment will be described below in detail. Specifically, at the moment of 1st microsecond (belonging to the first time period) in the first frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 1  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 1  coupled to the row driving line L 1 . At the moment of 2 nd  microsecond (belonging to the first time period) in the first frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 3  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 3  coupled to the row driving line L 3 . At the moment of 1 st  microsecond (belonging to the second time period) in the second frame period F 2 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 2  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 2  coupled to the row driving line L 2 . At the moment of 2 nd  microsecond (belonging to the second time period) in the second frame period F 2 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 4  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 4  coupled to the row driving line L 4 . In short, in this illustrated embodiment, the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) are sequentially lighted on in the first frame period F 1  with a forward scanning direction, and the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) are sequentially lighted on in the second frame period F 2  also with a forward scanning direction. In other words, the scanning direction of the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) being sequentially lighted on in the first frame period F 1  is the same as that of the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) being sequentially lighted on in the second frame period F 2 . 
     Referring to  FIG. 5(   b ), showing another scanning order used by the backlight driving method of  FIG. 2  in different frame periods. Herein, the first time period is in a first frame period F 1 , and the second time period is in a second frame period F 2 . A scanning time interval for row by row is assumed to be 1 microsecond and an exemplary embodiment will be described below in detail. Specifically, at the moment of 1st microsecond (belonging to the first time period) in the first frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 1  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 1  coupled to the row driving line L 1 . At the moment of 2 nd  microsecond (belonging to the first time period) in the first frame period F 1 , a row driving voltage provided from the row driver circuit  104  through the row driving line L 3  and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R 3  coupled to the row driving line L 3 . At the moment of 1 st  microsecond (belonging to the second time period) in the second frame period F 2 , a row driving voltage provided from the row driver circuit  104  through the row driving line L( 2 n) and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R( 2 n) coupled to the row driving line L( 2 n). At the moment of 2 nd  microsecond (belonging to the second time period) in the second frame period F 2 , a row driving voltage provided from the row driver circuit  104  through the row driving line L( 2 n− 2 ) and the column driving voltage have an enough voltage difference for lighting on the light-emitting diodes R( 2 n− 2 ) coupled to the row driving line L( 2 n− 2 ). In short, in this illustrated embodiment, the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) are sequentially lighted on in the first frame period F 1  with a forward scanning direction, and the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) are sequentially lighted on in the second frame period F 2  with a reverse scanning direction. In other words, the scanning direction of the first group of light-emitting rows L 1 , L 3 , . . . , L( 2 n− 1 ) being sequentially lighted on in the first frame period F 1  is different from that of the second group of light-emitting rows L 2 , L 4 , . . . , L( 2 n) being sequentially lighted on in the second frame period F 2 . 
     In summary, the above-mentioned embodiments of the present invention employ a multi-phase (e.g., 2-phase) scanning scheme to drive the light source array of a backlight module and make the backlight driving frequency be different from the gate driving frequency, so that breaking down a constant frequency difference between the gate driving frequency and the backlight driving frequency associated with the prior art which would cause the fan effect (i.e., generally waving noise or visual noise). Accordingly, the image quality of display device is improved. 
     The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including configurations ways of the recessed portions and materials and/or designs of the attaching structures. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.