CN102044223A - Liquid crystal display and driving method thereof - Google Patents

Abstract

A liquid crystal display and a driving method thereof. The liquid crystal display includes a liquid crystal display panel, a timing controller, and a source driver. The time schedule controller is used for providing periodic loading signals when the liquid crystal display is started initially. The source driver is coupled with the liquid crystal display panel and the time schedule controller and used for starting to receive the loading signal when the liquid crystal display is started initially, counting the times of the occurrence of the enabling potential of the loading signal to reach the preset times or detecting that the loading signal has passed the preset time, and outputting image picture data to drive and enable the liquid crystal display panel to display the image picture.

Description

Liquid crystal display and its driving method

technical field

The invention relates to a flat display, and in particular to a liquid crystal display and a driving method thereof.

Background technique

In recent years, with the vigorous development of semiconductor technology, portable electronic products and flat panel display products are also emerging. Among the types of flat panel displays, Liquid Crystal Display (LCD) has become the mainstream of various display products due to its advantages of low voltage operation, no radiation scattering, light weight and small size.

Generally speaking, when the liquid crystal display is initially powered on (initial power on), since the timing controller (timing controller) is used to control the source driver (source driver) to output the loading signal (load signal) TP of the image frame data Dout and the source The image frame data Dout output by the driver will be output synchronously (as shown in FIG. 1 ). Therefore, under this condition, if the source driver does not complete the reset (reset) action when the LCD is initially turned on (that is, the internal buffer of the source driver may still retain part of the image frame data or is some residual noise number), although the gate driver may not start to sequentially turn on the column pixels of the LCD panel with the scan signal at this time, but because the active elements of each pixel in the LCD panel (such as thin film transistors, TFT ) in the off state may cause the active components to be incompletely turned off due to the influence of the internal leakage current, so it is likely to cause the phenomenon of straight stripes when the liquid crystal display is initially turned on.

Contents of the invention

In view of this, the present invention provides a liquid crystal display, which does not appear the phenomenon of straight stripes when it is initially turned on.

The invention provides a liquid crystal display, which includes a liquid crystal display panel, a timing controller, and a source driver. Wherein, the timing controller is used for providing periodic loading signals when the liquid crystal display is initially turned on. The source driver is coupled to the liquid crystal display panel and the timing controller, and is used to start receiving the loading signal when the liquid crystal display is initially turned on, and start counting the number of occurrences of the enabling potential of the loading signal to reach a preset number of times or detect After the loading signal has passed a preset time, the image frame data is output to drive and cause the liquid crystal display panel to display the image frame.

In an exemplary embodiment of the present invention, when the source driver counts the number of occurrences of the enabling potential of the loading signal but does not reach the preset number of times or detects that the loading signal has not passed the preset time , the source driver outputs black frame data to drive and cause the liquid crystal display panel to display a black frame.

The present invention also provides a method for driving a liquid crystal display, which includes: providing a periodic loading signal when the liquid crystal display is initially turned on; After counting up to a preset number of times or detecting the loading signal for a preset time, output image frame data to drive and cause the liquid crystal display panel to display an image frame.

In an exemplary embodiment of the present invention, the driving method of the liquid crystal display further includes: when counting the number of occurrences of the enabling potential of the loading signal but not reaching the preset number of times or detecting that the loading signal has not experienced During the preset time, output black frame data to drive and cause the liquid crystal display panel to display a black frame.

The invention also provides a liquid crystal display, which includes a liquid crystal display panel, a timing controller, and a source driver. The timing controller is used to provide periodic loading signals when the liquid crystal display is initially turned on. The source driver includes an image frame data generating unit. The source driver is coupled to the LCD panel and the timing controller. When the source driver initially receives the loading signal, the image frame data generation unit correspondingly generates image frame data, and the source driver starts counting the number of occurrences of the enabling potential of the loading signal, and when the count reaches a preset outputting the image frame data to drive and cause the liquid crystal display panel to display the image frame after detecting the loading signal for a predetermined number of times or for a preset time.

In an exemplary embodiment of the present invention, the source driver further includes a black frame data generating unit for generating black frame data. When the source driver counts the number of occurrences of the enabling potential of the loading signal but has not reached the preset number of times or detects that the loading signal has not passed the preset time, the source driver outputs the black screen data to drive And cause the LCD panel to display a black screen.

The present invention mainly delays the loading signal used by the timing controller to control the source driver to output image frame data when the liquid crystal display is initially turned on, so as to output asynchronously with the image frame data output by the source driver. In this way, in the process of delaying the load signal output by the timing controller, the source driver is allowed to output black frame data to drive and cause the liquid crystal display panel to display a black frame. Therefore, the liquid crystal display of the present invention does not appear the phenomenon of straight stripes when the liquid crystal display is initially turned on.

It should be understood that the above general description and the following specific embodiments are only exemplary and explanatory, and should not limit the scope of the present invention.

Description of drawings

FIG. 1 is a schematic diagram of a traditional synchronously output loading signal TP and image frame data Dout;

FIG. 2 is a system block diagram of a liquid crystal display 200 according to an exemplary embodiment of the present invention;

FIG. 3 is a block diagram of a source driver 205 according to an exemplary embodiment of the present invention;

FIG. 4 is a schematic diagram of loading signal TP, image frame data Dout and black frame data Bout according to an exemplary embodiment of the present invention;

FIG. 5 is a flowchart of a driving method of a liquid crystal display according to an exemplary embodiment of the present invention.

Detailed ways

Reference will now be made in detail to several exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In addition, wherever possible, elements/components using the same reference numerals in the drawings and embodiments represent the same or similar parts.

FIG. 2 is a system block diagram of a liquid crystal display 200 according to an exemplary embodiment of the present invention. Referring to FIG. 2 , the liquid crystal display 200 includes a liquid crystal display panel 201 , a timing controller 203 , a source driver 205 , a gate driver 207 , and a backlight module 209 for providing backlight required by the liquid crystal display panel 201 . Wherein, the timing controller 203 is used to control the operation of the source driver 205 and the gate driver 207 .

To be more clear, the timing controller 203 controls the gate driver 207 to output scan signals in sequence to turn on each row of pixels in the liquid crystal display panel 201 . In addition, the timing controller 203 controls the source driver 205 to output image frame data Dout or black frame data Bout. In this exemplary embodiment, the timing controller 203 provides a periodic loading signal TP to the source driver 205 when the liquid crystal display 200 is initially turned on.

The source driver 205 is coupled to the liquid crystal display panel 201 and the timing controller 203, and is used to receive and count the number of occurrences of the load signal TP enabling potential. The frame data Bout is used to drive and cause the LCD panel 201 to display a black frame; and when the counting result reaches a preset number of times, the source driver 205 outputs the image frame data Dout to drive and cause the LCD panel 201 to display an image frame.

It can be seen from the content disclosed in the prior art that when the liquid crystal display is initially turned on, the loading signal (TP) used by the timing controller to control the source driver to output the image frame data (Dout) and the image frame data output by the source driver will be separated. Synchronous output, and output to the pixel data line of the liquid crystal display panel. In this way, together with various factors of the leakage current caused by the active elements (such as thin film transistors, TFT) of each pixel in the liquid crystal display panel being turned off, it is very likely that the liquid crystal display will appear to be turned on immediately when it is initially turned on. streak phenomenon.

In view of this, in the present exemplary embodiment, when the liquid crystal display 200 is initially turned on, the source driver 205 will not output the image immediately when the first enable potential (ie, the high voltage potential) of the loading signal TP appears. The image data Dout is sent to the pixel data line of the liquid crystal display panel to display the image, but the image image data Dout is output to the liquid crystal display panel after the loading signal TP passes through several enable potentials (or the loading signal TP passes through a preset period of time). The data line, that is, the image frame data Dout will be delayed and output. In other words, the image frame data Dout output by the source driver 205 will not be synchronously output to the liquid crystal display panel 201 when the first enabling potential of the loading signal TP appears. In addition, in this exemplary embodiment, after the liquid crystal display 200 is powered on, the source driver 205 will provide the black picture data Bout to the liquid crystal during the period from the start of receiving the load signal TP to the start of outputting the image picture data Dout to the liquid crystal display panel 201. The display panel 201 is used to make the liquid crystal display panel 201 display a black picture. Therefore, the liquid crystal display 200 in this exemplary implementation can greatly improve the phenomenon of straight stripes when the traditional display is turned on.

More specifically, FIG. 3 is a block diagram of the source driver 205 according to an exemplary embodiment of the present invention. Referring to FIG. 2 and FIG. 3 together, the source driver 205 includes an image frame data generating unit 301 , a black frame data generating unit 303 , a counting unit 305 , and an output multiplexing unit 307 . Wherein, the image frame data generation unit 301 is coupled to the timing controller 203 for receiving and processing the video signal (video signal) VS provided by the timing controller 203 to generate the image frame data Dout. Generally speaking, the image frame data generation unit 301 can be roughly composed of a shift register (shift register), a latch (latch) and a digital-to-analog converter (D/A converter). It is a skill familiar to those skilled in the art, so it will not be repeated here.

The black frame data generation unit 303 is used to generate the black frame data Bout, for example, the black frame data Bout of the ground potential, but not limited thereto. What is worth mentioning here is that the black frame data in this exemplary embodiment is generated by an additional black frame data generation unit 303 instead of the technology corresponding to this embodiment as in the conventional technology of block frame insertion (BFI). It is directly generated by the image frame data generation unit 301 of the example. The counting unit 305 is coupled to the timing controller 203 for receiving and counting the number of occurrences of the enabling potential of the loading signal TP, and outputting the selection signal SS accordingly. The output multitasking unit 307 is coupled to the video frame data generating unit 301, the black frame data generating unit 303, and the counting unit 305, to receive the selection signal SS, the video frame data Dout and the black frame data Bout, and determine the output according to the selection signal SS Image frame data Dout or black frame data Bout.

In this exemplary embodiment, when the liquid crystal display 200 is turned on by the user, for example, the user performs a power-on action, the counting unit 305 will receive the load signal TP from the timing controller 203 . In other words, the counting unit 305 starts to receive the loading signal TP after the liquid crystal display 200 is turned on, so as to start counting the number of occurrences of the enabling potential of the loading signal TP or the elapsed time of the loading signal TP, and correspondingly outputs the selection signal SS.

For example, after receiving the loading signal TP for the first time, the counting unit 305 starts counting the number of occurrences of the enabling potential of the loading signal TP or detects the elapsed time of the loading signal TP. When the counting unit 305 detects that the enabling potential of the loading signal TP has occurred for a predetermined number of times (for example, 7 times as shown in FIG. 4 , but not limited thereto) or detects that the loading signal TP has experienced a preset After the time T, the counting unit 305 will output the selection signal SS of the first logic state (for example, a high logic level) to the multiplexing unit 307 at this time. In this way, the output multiplexing unit 307 starts to output the image frame data Dout (shown as the bottom signal in FIG. 4 ) to the liquid crystal display panel 201 .

On the other hand, when the counting unit 305 counts the number of occurrences of the enabling potential of the loading signal TP but has not yet reached the aforementioned preset number of times (that is, less than 7 times) or when the time elapsed by the loading signal TP is less than the preset time T, The counting unit 305 then outputs the selection signal SS of the second logic state (for example, a low logic level) to the multiplexing unit 307 . In this way, the output multitasking unit 307 will output the black picture data Bout. In other exemplary embodiments of the present invention, the above-mentioned logic state of the selection signal SS can be changed according to actual design requirements, that is, a logic high becomes a logic low, and a logic low becomes a logic high, as long as the above-mentioned exemplary implementation is maintained The corresponding operation can be done.

Based on the above, FIG. 4 is a schematic diagram of the loading signal TP, the image frame data Dout and the black frame data Bout according to an exemplary embodiment of the present invention. Referring to FIGS. 2 to 4 , it can be clearly seen from FIG. 4 that the image frame data Dout output by the source driver 205 will not be synchronously output to the liquid crystal display at the same time as the first enabling potential 401 of the loading signal TP appears. Panel 201.

To be clearer, the counting unit 305 starts to receive the loading signal TP after the liquid crystal display 200 is turned on, so as to start counting the number of occurrences of the loading signal TP enabling potential 401 . Before the seventh enable potential 401 of the load signal TP appears (that is, before the number of times the enable potential 401 appears does not reach the preset number) or before the time elapsed by the load signal TP does not reach a preset time T, the source The driver 205 outputs the black frame data Bout through the output multiplexing unit 307 to drive and cause the liquid crystal display panel 201 to display a black frame. In addition, after the seventh enable potential 401 of the load signal TP provided by the timing controller 203 appears (that is, the number of occurrences of the enable potential 401 has reached the preset number of times) or the time elapsed by the load signal TP has reached the preset time. When the time T is set, the source driver 205 starts to output the actual image frame data Dout to the LCD panel 201 through the output multiplexing unit 307 , so that the LCD panel 201 displays an image frame. In particular, the output multitasking unit 307 of this embodiment can also be any switching element with a signal switching function or a related circuit with an equivalent function, and those skilled in the art should select or design this correspondingly depending on the actual application situation. Toggle elements.

In practice, the image frame data Dout generated by the image frame data generation unit 301 of the source driver 205 is still output synchronously with the load signal TP (as can be seen from the top and middle waveforms in FIG. 4 ), but due to the present embodiment The counting unit 305 starts to receive the loading signal TP after the liquid crystal display 200 is turned on, so as to start counting the number of occurrences of the loading signal TP enabling potential 401 or whether the predetermined time T has elapsed. In this way, the image frame data Dout generated by the image frame data generation unit 301 before the seventh enabling potential 401 of the load signal TP appears or before the time elapsed by the load signal TP does not reach a preset time T can be viewed as Incorrect image frame data (for example, when the source driver does not complete the reset operation when the LCD display is initially turned on, the internal buffer of the source driver retains part of the image frame data of the LCD display before it is turned off or some residual noise signals ). However, the image frame data deemed incorrect will not be output to the liquid crystal display panel before the seventh enabling potential 401 of the loading signal TP appears or before the time elapsed by the loading signal TP reaches a preset time T 201, in other words, as shown in FIG. 4, the source driver 205 of this embodiment, through the operation of the output multiplexing unit 307, when the seventh enabling potential 401 of the load signal TP appears or the load signal TP experiences After the time has reached a preset time T, the Dout generated by the image frame data generating unit 301 is captured, and the Dout (as shown in the waveform at the bottom of FIG. 4 ) is provided to the liquid crystal through the output multiplexing unit 307. The data line of the display panel 201 is used to display the correct image frame, that is, before the seventh enable potential 401 of the load signal TP appears or the time elapsed by the load signal TP does not reach a preset time T, the image frame The image frame data Dout source driver 205 generated by the data generation unit 301 will not be provided to the liquid crystal display panel; and before the seventh enable potential 401 of the load signal TP appears or the time elapsed by the load signal TP does not reach a period of time Before the preset time T, the black screen data generation unit 303 will generate the black screen data Bout to the liquid crystal display panel 201, that is, the Bout period shown in the waveform at the bottom of FIG. The black picture data Bout is sent to the liquid crystal display panel 201 . In this way, the source driver 205 can continuously output the black image data Bout before the correct image image data Dout starts to be written into the liquid crystal display panel 201, so that the liquid crystal display panel 201 displays a black image, thereby greatly improving the power-on problem that occurs when the traditional display is turned on. The phenomenon of straight stripes. On the other hand, after the seventh enable potential 401 of the load signal TP appears or the time elapsed by the load signal TP reaches a preset time T, the image frame data generation unit 301 generates the image frame data Dout to the The liquid crystal display panel 201 (as can be seen from the waveform at the bottom of FIG. 4 ), and it can be regarded as correct image frame data.

It can be seen from this that when the liquid crystal display 200 is initially turned on, the real (correct) image frame data Dout output by the source driver 205 of this embodiment will not be output at the same time as the first enabling potential 401 of the loading signal TP appears. to the liquid crystal display panel 201, and its black picture data Bout is not directly provided by the image picture data generating unit as in the traditional technique, but is provided by the black picture data generating unit 303 in addition, that is, the image picture data Dout and the black picture The generation mechanisms or sources of data Bout are different. Also because of this, even if the source driver 205 does not complete the reset operation when the liquid crystal display 200 is initially turned on, the gate driver 207 does not sequentially scan signals to turn on the column pixels of the liquid crystal display panel 201, and each pixel in the liquid crystal display panel 201 Various factors of the leakage current caused when the active components (such as thin film transistors, TFT) are turned off will not cause the phenomenon of vertical stripes when the liquid crystal display 201 is initially turned on.

It is worth mentioning here that the preset number of times mentioned in the above exemplary embodiment is 7 times as an example for illustration, but the present invention is not limited thereto. That is to say, the user can determine the value of the preset number of times according to actual design requirements. Generally speaking, the preset number of times can be designed to be greater than 3, preferably, the preset number of times can be designed to be greater than 6 and less than 10, but not limited thereto. In addition, the counting method of the so-called preset times in the present invention refers to counting starts when the counting unit 305 starts to receive the load signal TP after the liquid crystal display 200 is turned on. The so-called power-on event or initial power-on event in the present invention refers to that the display screen is turned on again after being turned off. The display screen here can be a display screen connected to the computer host or a display screen or a TV integrated with the computer host. display screen etc. That is, before the liquid crystal display 200 is turned on, the source driver in the liquid crystal display 200 does not provide any image frame data Dout signal to the data line of the liquid crystal display panel 201 .

In addition, although the counting unit 305, the output multiplexing unit 307 and the black screen data generating unit 303 are arranged in the source driver in the above exemplary embodiment, in another exemplary embodiment, these elements can also be arranged in other suitable place (such as set in the Tcon circuit board) or integrated in other components. Furthermore, the architecture shown in FIG. 3 is an implementation of the driving method of the present invention. The hardware design architecture of the present invention is not limited to the design shown in FIG. 3 . The hardware design of the method is applicable.

FIG. 5 is a flowchart of a driving method of a liquid crystal display according to an exemplary embodiment of the present invention. Referring to FIG. 5 , the driving method of the liquid crystal display in this exemplary embodiment includes: when the liquid crystal display is initially turned on, providing a periodic loading signal (step S501); then, when the liquid crystal display is initially turned on, enabling the loading signal The number of potential occurrences is counted and it is judged whether the preset number has been reached, or whether the loading signal has passed the preset time (step S503 ).

In this exemplary embodiment, when the judgment or detection result in step S503 is that the number of occurrences of the enabling potential of the loading signal has reached the preset number of times, or the loading signal has passed the preset time, the image frame data is output to the liquid crystal display panel to display the correct image frame (step S505). On the other hand, when the judgment or detection result in step S503 is that the number of occurrences of the enabling potential of the loading signal does not reach the preset number of times, or when the loading signal has not passed the preset time, the black picture data is output to the liquid crystal display panel to display black screen (step S507).

In summary, the present invention mainly delays the loading signal used by the timing controller to control the source driver to output the image frame data when the liquid crystal display is initially turned on, so as to be out of sync with the image frame data output by the source driver output. In this way, in the process of delaying the load signal output by the timing controller, the source driver is allowed to output black frame data to drive and cause the liquid crystal display panel to display a black frame. Therefore, the liquid crystal display of the present invention does not appear the phenomenon of straight stripes when the liquid crystal display is initially turned on.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall prevail as defined by the appended claims.

Claims (20)

1. LCD comprises:

Display panels;

Time schedule controller when being used to described LCD and initially starting shooting, provides periodic load signal; And

Source electrode driver, couple described display panels and described time schedule controller, be used to begin to receive described load signal when described LCD is initially started shooting, and to the number of times that described load signal activation current potential occurs begin to count and reach preset times or detect described load signal experienced Preset Time after, the image output picture data to described display panels so that described display panels show image picture.

2. LCD as claimed in claim 1, wherein the number of times that described load signal activation current potential is occurred when described source electrode driver is counted and is not reached described preset times or detect described load signal when not experiencing described Preset Time, and the black picture data of described source electrode driver output shows black picture to drive and to cause described display panels.

3. LCD as claimed in claim 2, wherein said source electrode driver comprises:

Image frame data generation unit couples described time schedule controller, in order to receive and the vision signal that described time schedule controller provided is handled, uses the described image frame data of generation;

Black picture data generation unit is in order to produce described black picture data;

Counting unit couples described time schedule controller, count or detect the time that described load signal experiences in order to reception and to the number of times that described load signal activation current potential occurs, and signal is selected in output according to this; And

The output multi-task unit, couple described image frame data generation unit, described black picture data generation unit and described counting unit, in order to receiving described selection signal, described image frame data and described black picture data, and determine to export described image frame data or described black picture data according to described selection signal.

4. LCD as claimed in claim 3, wherein the number of times that described load signal activation current potential is occurred when described counting unit is counted and is reached described preset times or detect described load signal when having experienced described Preset Time, and described counting unit is exported the described selection signal of first logic state.

5. LCD as claimed in claim 4, wherein when described counting unit was exported the described selection signal of described first logic state, described output multi-task unit was exported described image frame data.

6. LCD as claimed in claim 4, wherein the number of times that described load signal activation current potential is occurred when described counting unit is counted and is not reached described preset times or detect described load signal when not experiencing described Preset Time, and described counting unit is exported the described selection signal of second logic state.

7. LCD as claimed in claim 6, wherein when described counting unit was exported the described selection signal of described second logic state, described output multi-task unit was exported described black picture data.

8. LCD as claimed in claim 6, wherein said first logic state is a logic high potential, and described second logic state is a logic low potential.

9. LCD as claimed in claim 6, wherein said first logic state is a logic low potential, and described second logic state is a logic high potential.

10. LCD as claimed in claim 1, wherein said preset times is greater than 6 and less than 10.

11. the driving method of a LCD comprises:

When described LCD is initially started shooting, provide periodic load signal; And

When described LCD is initially started shooting, begin to the number of times that described load signal activation current potential occurs count and reach preset times or detect described load signal experienced Preset Time after, the image output picture data to display panels so that described display panels show image picture.

12. the driving method of LCD as claimed in claim 11 also comprises:

Do not reach described preset times or detect described load signal when not experiencing described Preset Time when the number of times of described load signal activation current potential appearance is counted, the black picture data of output is deceived picture to drive and to cause described display panels to show.

13. the driving method of LCD as claimed in claim 11, wherein said preset times is greater than 6 and less than 10.

14. a LCD comprises:

Display panels;

Time schedule controller when being used to described LCD and initially starting shooting, provides periodic load signal; And

Source electrode driver, comprise image frame data generation unit, described source electrode driver couples described display panels and described time schedule controller, when the described load signal of the initial reception of described source electrode driver, described image frame data generation unit produces the image frame data accordingly, described source electrode driver and the number of times that described load signal activation current potential is occurred begin to count, in described counting reach preset times or detect described load signal experienced Preset Time after, the described image frame data of beginning output to described display panels so that described display panels show image picture.

15. LCD as claimed in claim 14, wherein said source electrode driver also comprises black picture data generation unit, in order to produce black picture data, the number of times that described load signal activation current potential is occurred when described source electrode driver is counted and is not reached described preset times as yet or detect described load signal when not experiencing described Preset Time, and described source electrode driver is exported described black picture data and shown black picture to drive and to cause described display panels.

16. LCD as claimed in claim 15, wherein said source electrode driver also comprises:

Counting unit couples described time schedule controller, count or detect the time that described load signal experiences in order to reception and to the number of times that described load signal activation current potential occurs, and signal is selected in output according to this; And

The output multi-task unit, couple described image frame data generation unit, described black picture data generation unit and described counting unit, in order to receiving described selection signal, described image frame data and described black picture data, and determine to export described image frame data or described black picture data according to described selection signal.

17. LCD as claimed in claim 16, wherein the number of times that described load signal activation current potential is occurred when described counting unit is counted and is reached described preset times or detect described load signal when having experienced described Preset Time, described counting unit is exported the described selection signal of first logic state, uses to make described output multi-task unit export described image frame data.

18. LCD as claimed in claim 17, wherein the number of times that described load signal activation current potential is occurred when described counting unit is counted and is not reached described preset times or detect described load signal when not experiencing described Preset Time, described counting unit is exported the described selection signal of second logic state, uses to make described output multi-task unit export described black picture data.

19. LCD as claimed in claim 17, wherein said first logic state are one of them of logic high potential and logic low potential, and described second logic state is wherein another of described logic high potential and described logic low potential.

20. LCD as claimed in claim 14, wherein said preset times is greater than 6 and less than 10.

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