Patent Publication Number: US-9886890-B2

Title: Display device and method for displaying an image thereon

Description:
TECHNICAL FIELD 
     The present invention relates to the field of display technology, and more particularly to a display device and a method for displaying an image thereon. 
     BACKGROUND OF THE INVENTION 
     In the conventional TFT-LCD (Thin Film Transistor Liquid Crystal Display), there is often parasitic capacitance Cgd. When the current/voltage of the gate line changes, the parasitic capacitance Cgd will produce the capacitive coupling (Feed Through) voltage ΔV, so that it cannot use the common voltage Vcom as a middle value in respect to which the voltage changes symmetrically when the voltage forms polarity inversion, which causes DC residual effects to appear. 
     Under the influence of the DC residual effects above, if the voltage of the bipolar plate of LCD capacitive of the thin film transistor liquid crystal display panel remains the same value for a long time, then the residual and movable ions in the liquid crystal molecules can move in the same electric field direction to accumulate on the same side of the liquid crystal molecules, thereby forming an inner electric field. 
     When the displaying image (as shown in  FIG. 1 ) of the thin film transistor liquid crystal display turns from a high gray scale to a low gray scale, the inner electric field and the electric field between the plates of the liquid crystal capacitance are offset with each other, so that the liquid crystal molecules cannot be twisted to a predetermined angle, which will eventually lead to an image sticking phenomenon, as shown in  FIG. 2 . 
     In particular, in the process of users who use mobile phones, tablet computers, desktop computers, and other electronic products, since the screen area of the electronic products will sometimes display a static picture for a long time. When the screen is switched, the screen of the electronic products will produce an image sticking phenomenon which is easily recognizable to the human eye. 
     In order to reduce the above image sticking phenomenon, the conventional technical solutions are: the asymmetric adjustment is used to grayscale voltage which is used to display images. 
     Due to the nature of the portion of parts or materials of the conventional displaying panel (e.g., the nature of the liquid crystal material) having variations over time (changing with time and having varying characteristics), the optimum common voltage value of the conventional display panel will vary with time variation, and the above portion of parts or materials of the conventional displaying panel are able to stabilize after booting for a long time. During this long time, if the Vcom, etc., are kept constant, then the flicker rate of the conventional display panel image will be in a variation state continuously, as shown in  FIG. 3 , which would greatly increase the image sticking phenomenon. 
     Therefore, it is necessary to propose a new technical solution to solve the above technical problems. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a display device and a method for displaying an image thereof, which can make the blink rate of a display image of the display device vary with time to be kept within a stable range, thereby improving the display quality. 
     In order to solve the above problems, the technical solutions of the present invention are as follows: A display device, comprising: a display panel, used for displaying an image according to a first gray scale voltage signal and a first common voltage signal; a gray scale voltage output circuit, used for outputting the first gray scale voltage signal to the display panel; a common voltage output circuit, used for outputting the first common voltage signal to display panel; and a control circuit being used at the predetermined time for controlling the gray scale voltage output circuit and the common voltage output circuit respectively outputting the second gray scale voltage signal and the second common voltage to the display panel; wherein the second gray scale voltage signal and the second common voltage signal are supplied to the display panel for displaying another image, and for causing a blink rate of the displayed image of the display panel to be within a predetermined range; the display device further comprising: a timer, used for calculating a display time of the display panel; the control circuit used for deciding whether the predetermined time arrives or not in accordance with the display time, when at the predetermined time, controlling the gray scale voltage output circuit and the common voltage output circuit respectively to output the second gray scale voltage signal and the second common voltage signal to the display panel; the gray scale voltage output circuit and the common voltage output circuit both connect to the display panel, and the control circuit connects with the gray scale voltage output circuit and the common voltage output circuit. 
     In the display device above, the display device further comprises: a memory used for storing therein a second gray scale voltage value and a second common voltage value in advance; a control circuit reads the second gray scale voltage value and the second common voltage value from the memory when at the predetermined time, and according to the second gray scale voltage value and the second common voltage value, controls the gray scale voltage output circuit and the common voltage output circuit respectively to output the second gray scale voltage signal and the second common voltage to the display panel; wherein the second gray scale voltage signal is corresponding to the second gray scale voltage value, the second common voltage signal is corresponding to the second common voltage value. 
     In the display device above, the memory stores a set of preset data, the set of preset data includes a time information, at least one of the second gray voltage values and at least one of the second common voltage values; the second gray scale voltage value and the second common voltage value both corresponding to the time information; the control circuit used for comparing the display time with the time corresponding to the time information, and generating a comparison result, according to the comparison result, reads the second gray scale voltage value and the second common voltage value from the memory when at the predetermined time, and according to the second gray scale voltage value and the second common voltage value, controls the gray scale voltage output circuit and the common voltage output circuit respectively to output the second gray scale voltage signal and the second common voltage to the display panel. 
     In the display device above, the second gray voltage value and the second common voltage value are previously measured according to the display panel samples at different times points, in order to keep the blink rate of the image which is within the predetermined range of the desired gray scale voltage signal and the common voltage signal. 
     In the display device above, the display device comprises: a display panel, which according to a first gray scale voltage signal and a first common voltage signal, displays an image; a gray scale voltage output circuit, used for outputting the first gray scale voltage signal to the display panel; a common voltage output circuit, used for outputting the first common voltage signal to the display panel; and a control circuit controls the gray scale voltage output circuit and the common voltage output circuit respectively to output a second gray scale voltage signal and a second common voltage to the display panel when at the predetermined time; wherein the second gray scale voltage signal and the second common voltage signal are supplied to the display panel for displaying another image, and for causing a blink rate of the displayed image of the display panel to be within a predetermined range. 
     In the display device above, the display device further comprises: a timer, used for calculating a display time of the display panel; a control circuit used for deciding whether the predetermined time arrives or not, in accordance with the display time, when at the predetermined time, controls the gray scale voltage output circuit and the common voltage output circuit respectively to output the second gray scale voltage signal and the second common voltage signal to the display panel. 
     In the display device above, the display device further comprises: a memory for storing therein a second gray scale voltage value and a second common voltage value in advance; a control circuit reads the second gray scale voltage value and the second common voltage value from the memory when at the predetermined time, and according to the second gray scale voltage value and the second common voltage value, controls the gray scale voltage output circuit and the common voltage output circuit respectively to output the second gray scale voltage signal and the second common voltage to the display panel. 
     In the display device above, the second gray scale voltage signal corresponds to the second gray scale voltage value, the second common voltage signal corresponds to the second common voltage value. 
     In the display device above, the memory stores a set of preset data, the set of preset data includes a time information, at least one of the second gray voltage values, and at least one of the second common voltage values; the second gray scale voltage value and the second common voltage value both corresponding to the time information. 
     In the display device above, the control circuit compares the display time with the time corresponding to the time information, and generates a comparison result, according to the comparison result, the control circuit reads the second gray scale voltage value and the second common voltage value from the memory when at the predetermined time, and according to the second gray scale voltage value and the second common voltage value, the control circuit controls the gray scale voltage output circuit and the common voltage output circuit respectively to output the second gray scale voltage signal and the second common voltage to the display panel. 
     In the display device above, the second gray voltage value and the second common voltage value are previously measured according to the display panel samples at different time points, in order to keep the blink rate of the image within the predetermined range of the desired gray scale voltage signal and the common voltage signal. 
     In the display device above, the gray scale voltage output circuit and the common voltage output circuit are both connected to the display panel, and the control circuit is connected with the gray scale voltage output circuit and the common voltage output circuit. 
     A method for displaying an image of the display device above, the method including steps below: A, the gray scale voltage output circuit and the common voltage output circuit, respectively are used for outputting a first gray scale voltage signal, and used for outputting a first common voltage signal to the display panel; B, the display panel displays an image according to the first gray scale voltage signal and the first common voltage signal; and C, when at a predetermined time thereafter, the control circuit controlling the gray scale voltage output circuit and the common voltage output circuit respectively and outputting a second gray scale voltage signal and a second common voltage to the display panel; wherein the second gray scale voltage signal and the second common voltage signal are supplied to the display panel for displaying another image, and for causing the blink rate of the displayed image of the display panel to be within a predetermined range. 
     A method for displaying an image of the display device above, the method furthermore includes the following steps below: Step D, having the timer to calculate a display time of the display panel; step C including the following steps: c1, the control circuit, in accordance with the display time, deciding whether the predetermined time arrives or not; and c2, when at the predetermined time, controlling the gray scale voltage output circuit and the common voltage output circuit respectively and outputting the second gray scale voltage signal and the second common voltage signal to the display panel. 
     A method for displaying an image of the display device above, the step c2 including the following steps: c21, the control circuit reads the second gray scale voltage value and the second common voltage value from the memory when at the predetermined time; and c22, according to the second gray scale voltage value and the second common voltage value, controlling the gray scale voltage output circuit and the common voltage output circuit respectively and outputting the second gray scale voltage signal and the second common voltage to the display panel. 
     A method for displaying an image of the display device above, the second gray scale voltage signal corresponds to the second gray scale voltage value, the second common voltage signal corresponds to the second common voltage value. 
     A method for displaying an image of the display device above, the memory stores a set of preset data therein, the set of preset data including a time information, at least one of the second gray voltage values and at least one of the second common voltage values, the second gray scale voltage value and the second common voltage value both correspond to the time information. 
     A method for displaying an image of the display device above, the step c1 including the following step: c11, the control circuit comparing the display time with the time corresponding to the time information, and generating a comparison result; the step c21 includes the following step: c211, according to the comparison result, when at the predetermined time, the control circuit reading the second gray scale voltage value and the second common voltage value from the memory. 
     A method for displaying an image of the display device above, the second gray voltage value and the second common voltage value are previously measured according to the display panel samples at different time points, in order to keep the blink rate of the image within the predetermined range of the desired gray scale voltage signal and the common voltage signal. 
     Relative to the prior art, the present invention can make the blink rate of display image of the display device vary with time to be kept within a stable range, thereby improving display quality. 
     To allow the above present invention to be more clearly comprehensible, preferred embodiments, with the accompanying drawings, are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of the displayed image of a conventional display panel. 
         FIG. 2  is a schematic diagram of an image sticking phenomenon of the displayed image obtained from the displayed image shown in  FIG. 1 . 
         FIG. 3  is a schematic diagram of the conventional display panel flicker rate in respect to time. 
         FIG. 4  is a block diagram of a first embodiment of the display device of the present invention. 
         FIG. 5  is a block diagram of a second embodiment of the display device of the present invention. 
         FIG. 6  is a block diagram of a third embodiment of the display device of the present invention. 
         FIG. 7  is a schematic diagram of the display panel flicker rate in respect to time in accordance with the display device of the present invention. 
         FIG. 8  is a flowchart of a first embodiment of a method for the display device displaying an image of the present invention. 
         FIG. 9  is a flowchart of a second embodiment of a method for the display device displaying an image of the present invention. 
         FIG. 10  is a flowchart of a third embodiment of a method for the display device displaying an image of the present invention. 
         FIG. 11  is a flowchart of a fourth embodiment of a method for the display device displaying an image of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Regarding the terms as used in this specification, “an embodiment” means an instance, an example, or an illustration. In addition, the articles in this specification and the appended claims, the use of “one” in general can be interpreted as “one or more” unless specified otherwise or clear from context to determine the singular form. 
     Please refer to  FIG. 4 , which is a block diagram of a first embodiment of the display device of the present invention. 
     The display device of the present embodiment includes a display panel  401 , a gray scale voltage output circuit  402 , a common voltage output circuit  403 , and a control circuit  404 . The gray scale voltage output circuit  402  and the common voltage output circuit  403  are connected with the display panel  401 . The control circuits  404  is connected with the gray-scale voltage output circuit  402  and the common voltage output circuit  403 . The display panel  401  may be a TFT-LCD (Thin Film Transistor Liquid Crystal Display) panel, OLED (Organic Light Emitting Diode Display) panel, and the like. 
     The display panel  401 , according to a first gray scale voltage signal and a first common voltage signal, displaying an image; the gray scale voltage output circuit  402  is used for outputting the first gray scale voltage signal to the display panel  401 ; the common voltage output circuit  403  is used for outputting the first common voltage signal to display panel  401 ; and the control circuit  404 , when at the predetermined time, controls the gray scale voltage output circuit  402  and the common voltage output circuit  403  respectively and outputs the second gray scale voltage signal and the second common voltage to the display panel  401 . 
     The second gray scale voltage signal and the second common voltage signal are supplied to the display panel  401  for displaying another image, and for causing a blink rate of the displayed image of the display panel  401  to be within a predetermined range. 
     Through the technical solution above, the blink rate can be maintained over time in a relatively fixed range (the predetermined range), thereby improving display quality. 
     Please refer to  FIG. 5 , which is a block diagram of a second embodiment of the display device of the present invention. 
     The present embodiment is similar to the first embodiment, except that in the present embodiment, the display device further includes a timer  501 . 
     The timer  501  is used for calculating a display time of the display panel  401 . 
     The control circuit  404 , in accordance with the display time, is used for deciding whether the predetermined time arrives or not, and when at the predetermined time, controls the gray scale voltage output circuit  402  and the common voltage output circuit  403  respectively to output the second gray scale voltage signal and the second common voltage signal to the display panel  401 . 
     As shown in  FIG. 7 , the line  702  corresponding to a second common voltage value which is different at different time periods, i.e., the second common voltage varies over time, and the blink rate corresponding to the curve line  701  that varies over time remains stable. 
     Please refer to  FIG. 6 , which is a block diagram of a third embodiment of the display device of the present invention. 
     The present embodiment is similar to the second embodiment, except that in the present embodiment, the display device further includes a memory  601 . 
     The memory  601  is used for storing therein a second gray scale voltage value and a second common voltage value in advance. 
     The control circuit  404 , when at the predetermined time, is used for reading the second gray scale voltage value and the second common voltage value from the memory  601 , and according to the second gray scale voltage value and the second common voltage value, controls the gray scale voltage output circuit  402  and the common voltage output circuit  403  respectively for outputting the second gray scale voltage signal and the second common voltage to the display panel  401 . 
     The second gray scale voltage signal corresponds to the second gray scale voltage value, the second common voltage signal corresponds to the second common voltage value. 
     The fourth embodiment of the present invention is similar to the third embodiment, except that: 
     In the present embodiment, the memory  601  stores a set of preset data, the set of preset data includes a time information, at least one of the second gray voltage values, and at least one of the second common voltage values. 
     The second gray scale voltage value and the second common voltage value both correspond to the time information. 
     The control circuit  404  is used for comparing the display time with the time corresponding to the time information, and generating a comparison result. According to the comparison result, when at the predetermined time, it is used for reading the second gray scale voltage value and the second common voltage value from the memory  601 , and according to the second gray scale voltage value and the second common voltage value, it is used for controlling the gray scale voltage output circuit  402  and the common voltage output circuit  403  respectively for outputting the second gray scale voltage signal and the second common voltage to the display panel  401 . 
     The second gray voltage value and the second common voltage value are previously measured according to the display panel samples at different time points, in order to keep the blink rate of the image within the predetermined range of the desired gray scale voltage signal and the common voltage signal. 
     Please refer to  FIG. 8 , which is a flowchart of a first embodiment of a method for the display device displaying an image of the present invention. 
     A method for a display device to display images, the display device comprising a display panel, a gray scale voltage output circuit in connection with the display panel, a common voltage output circuit in connection with the display panel, and a control circuit in connection with both the gray scale voltage output circuit and the common voltage output circuit, wherein the method includes the following steps: 
     A (Step  801 ), having the gray scale voltage output circuit  402  and the common voltage output circuit  403  are respectively used for outputting a first gray scale voltage signal and a first common voltage signal to the display panel  401 . 
     B (Step  802 ), then the display panel  401  displays an image according to the first gray scale voltage signal and the first common voltage signal; and 
     C (Step  803 ), when at a predetermined time thereafter, the control circuit  404  is used for controlling the gray scale voltage output circuit  402  and the common voltage output circuit  403  respectively for outputting a second gray scale voltage signal and a second common voltage to the display panel  401 . 
     The second gray scale voltage signal and the second common voltage signal are supplied to the display panel  401  for displaying another image, and for causing the blink rate of the displayed image of the display panel  401  to be within a predetermined range. 
     Through the technical solution above, the blink rate can be maintained over time in a relatively fixed range (the predetermined range), thereby improving display quality. 
     Please refer to  FIG. 9 , which is a flowchart of a second embodiment of a method for the display device displaying an image of the present invention. The present embodiment is similar to the first embodiment, except that: 
     In the present embodiment, the display device further comprising a timer, the method further includes: 
     D (Step  901 ), having the timer  501  to calculate a display time of the display panel  401 . 
     The step C (i.e., Step  803 ) includes the following steps: 
     c1 (Step  8031 ), the control circuit  404 , in accordance with the display time, is used for deciding whether the predetermined time arrives or not; and 
     c2 (Step  8032 ), when at the predetermined time, controlling the gray scale voltage output circuit  402  and the common voltage output circuit  403  respectively to output the second gray scale voltage signal and the second common voltage signal to the display panel  401 . 
     As can be seen from  FIG. 7 , the line  702  corresponding to a second common voltage value is different at different time periods, i.e., the second common voltage varies over time, and the blink rate corresponding to the curve line  701  that varies over time remains stable. 
     Please refer to  FIG. 10 , which is a flowchart of a third embodiment of a method for the display device displaying an image of the present invention. The present embodiment is similar to the second embodiment, except that: 
     In the present embodiment, the display device further comprising a memory stored therein a second gray scale voltage value and a second common voltage value, the step c2 (i.e., Step  8032 ) including the following steps: 
     c21 (Step  80321 ), the control circuit  404  reads the second gray scale voltage value and the second common voltage value from the memory  601  when at the predetermined time; and 
     c22 (Step  80322 ), according to the second gray scale voltage value and the second common voltage value, the control circuit  404  is used for controlling the gray scale voltage output circuit  402  and the common voltage output circuit  403  respectively to output the second gray scale voltage signal and the second common voltage to the display panel  401 . 
     The second gray scale voltage signal corresponds to the second gray scale voltage value, and the second common voltage signal corresponds to the second common voltage value. 
     Please refer to  FIG. 11 , which is a flowchart of a fourth embodiment of a method for the display device displaying an image of the present invention. The present embodiment is similar to the third embodiment, except that: 
     In the present embodiment, the memory  601  stores therein a set of preset data, the set of preset data includes a time information, at least one of the second gray voltage values and at least one of the second common voltage values. 
     The second gray scale voltage value and the second common voltage value both correspond to the time information. 
     The step c1 (i.e., Step  8031 ) includes the following step: 
     c11 (step  1101 ), the control circuit  404  is used for comparing the display time with the time corresponding to the time information, and generating a comparison result. 
     The step c21 (i.e., the Step  80321 ) includes the following step: 
     c211 (Step  1102 ), according to the comparison result, the control circuit used for reading the second gray scale voltage value and the second common voltage value from the memory  601  when at the predetermined time. 
     In any one embodiment of the above first embodiment to fourth embodiments, the second gray voltage value and the second common voltage value are previously measured according to display panel samples at different time points, in order to keep the blink rate of the image within the predetermined range of the desired gray scale voltage signal and the common voltage signal. 
     Despite the fact that present invention has been shown and described in relation to one or more implementations, those skilled in the art, based on reading and understanding the specification and drawings, would expect equivalent variations and modifications. The present invention includes all such modifications and variations, and is only limited by the scope of the appended claims. Particularly with regard to the various functions performed by the above described components, the terms used to describe such components are intended to perform the function corresponding to the specified component (e.g., that is functionally equivalent) of any component (unless otherwise indicated), even if a structure is not the same as the disclosed structure which executes the functions of the exemplary implementations in the present specification. In addition, although a particular feature of this specification has been disclosed by only one of a number of implementations, this feature can be combined with one or more other combinations of features of other implementations for given or specific applications as desired and advantageous. Furthermore, the terms “including”, “having”, “containing”, or variations thereof as used in the detailed description or the claims are intended to be used in a manner similar to the term “comprising”. 
     In summary, although the present invention has been described in preferred embodiments above, the preferred embodiments described above are not intended to limit the invention. One of ordinary skill in the art without departing from the spirit and scope of the invention can make all species of modifications and variations, so the protection scope of the invention is defined by the claims.