In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments are possible.
In accordance with some embodiments, in response to an increase in refresh frequency of a liquid crystal display (LCD) device, a driving unit in the LCD device outputs at least one overdrive frame data to prolong the time that the overdrive voltage remains on a pixel electrode of the LCD device. The term “frame data” can refer to frame data used to drive a pixel. Alternatively, the term “frame date” can refer to data used to drive plural pixels. As a result, the issue that the display quality of the LCD device is affected by insufficient brightness of pixels can be addressed.
The buffer 2022 is for storing a previous original frame data F(n−1) and a current original frame data F(n) corresponding to a pixel. The buffer 2022 provides a first previous adjusted frame data F1(n−1) and a second previous adjusted frame data F2(n−1) according to the previous original frame data F(n−1). Also, the buffer 2022 generates a first current adjusted frame data F1(n) and a second current adjusted frame data F2(n) according to the current original frame data F(n).
The first overdrive data generation unit 20211 receives the first previous adjusted frame data F1(n−1) and the first current adjusted frame data F1(n) and, in response, outputs a first current overdrive frame data SOD1(n) according to the first previous adjusted frame data F1(n−1), the first current adjusted frame data F1(n), and a first look-up table. The first look-up table maps inputs of F1(n−1) and F1(n) to an overdrive frame data value. This is, for each combination of F1(n−1) and F1(n), an overdrive frame data value could be consulted and outputted. The first overdrive data generation unit 20211 outputs the first current overdrive frame data SOD1(n) as the output frame data SO(n) to the source driver 204.
The second overdrive data generation unit 20212 receives the second previous adjusted frame data F2(n−1) and the second current adjusted frame data F2(n), and in response, outputs a second current overdrive frame data SOD2(n) according to the second previous adjusted frame data F2(n−1), the second current adjusted frame data F2(n), and a second look-up table. The second look-up table maps the difference between F2(n) and F2(n−1) with an overdrive frame data value. The delay unit 20213 receives the second current overdrive frame data SOD2(n) and delays the second current overdrive frame data SOD2(n). After a predetermined delay time period, the delay unit 20213 outputs the second current overdrive frame data SOD2(n) as the output frame data SO(n) to the source driver 204.
Then, in step 306, the first current overdrive frame data SOD1(n) is produced according to the first previous adjusted frame data F1(n−1), the first current adjusted frame data F1(n), and the first look-up table. Also, the first current overdrive frame data SOD1(n) is output as the output frame data SO(n) to the source driver 204 (see row corresponding to SO(n) in
When the driving unit 202 of an embodiment doubles the frequency of the output frame data SO(n) (for example, the frequency is increased to 120 Hz from 60 Hz), the first and second current overdrive frame data SOD1(n) and SOD2(n) are output as the output frame data SO(n) to the source driver 204 during the frame periods TS1′(n) and TS2′(n), respectively. The time that the overdrive voltage corresponding to the output frame data SO(n), driven with SOD1(n) and SOD2(n) in the periods TS1′(n) and TS2′(n), respectively, remains on the pixel electrode is prolonged in accordance with an embodiment. Therefore, the issue of a pixel not reaching a target brightness due to a long reaction time of the liquid crystal molecules in the regions 102 and 104 in
As shown in
Then, in step 506, the first current overdrive frame data SOD1(n) is produced according to the first previous adjusted frame data F1(n−1), the first current adjusted frame data F1(n), and a look-up table. Also, the first current overdrive frame data SOD1(n) is output as the output frame data SO(n) to the source driver 404. After a predetermined delay time period, the first current overdrive frame data SOD1(n) is output again as the output frame data SO(n) to the source driver 404.
The driving unit 402 outputs the first current overdrive frame data SOD1(n) twice during the frame periods TS1′(n) and TS2′(n). As a result, even when the frequency of the output frame data SO(n) is twice as large as the frequency of the original frame data F(n), the time that the overdrive voltage corresponding to the output frame data SO(n) remains on the pixel electrode is prolonged.
The driving unit 602 includes a buffer 6022, a timing controller 6021, and a memory 6023. The difference between the third embodiment and the second embodiment is that the timing controller 6021 of the driving unit 602 in the third embodiment is able to determine if the previous original frame data F(n−1) and the current original frame data F(n) are within a predetermined range. The predetermined range can be the regions 102 or 104 in
When the previous original frame data F(n−1) and the current original frame data F(n) are within the predetermined range, the timing controller 6021 outputs the first current overdrive frame data SOD1(n) as the output frame data SO(n) in the period TS1′(n) to the source driver 604 according to the first previous adjusted frame data F1(n−1), the first current adjusted frame data F1(n), and a look-up table. After a predetermined delay time period, the timing controller 6021 outputs the first current overdrive frame data SOD1(n) in the time period TS1′(n) as the output frame data SO(n) again to the source driver 604. In other words, during the frame periods TS1′(n) and TS2′(n), the driving unit 602 outputs the first current overdrive frame data SOD1(n) twice as the output frame data SO(n) to the source driver 604.
As depicted in
For example, the timing controller 6021 determines if the previous original frame data F(n−1) and the current original frame data F(n) are within the predetermined range according to a data minimum deviation value. The timing controller 6021 compares the previous original frame data F(n−1) and the current original frame data F(n) to obtain a data deviation value (difference) of the previous original frame data F(n−1) and the current original frame data F(n). The timing controller 6021 compares the data deviation value and the data minimum deviation value. When the data deviation value is greater than or equal to the data minimum deviation value, the timing controller 6021 determines that the previous original frame data F(n−1) and the current original frame data F(n) are within the predetermined range. When the data deviation value is less than the data minimum deviation value, the timing controller 6021 determines that the previous original frame data F(n−1) and the current original frame data F(n) are outside the predetermined range. The data minimum deviation value is a predetermined parameter stored in the timing controller 6021.
On the other hand, in step 710, if the previous original frame data F(n−1) and the current original frame data F(n) are determined at 706 to be outside the predetermined range, the first current overdrive frame data SOD1(n) is output as the output frame data SO(n) to the source driver 604 according to the first previous adjusted frame data F1(n−1), the first current adjusted frame data F1(n), and the look-up table. After the predetermined delay time period, the second current adjusted frame data F2(n) is output as the output frame data SO(n) to the source driver 604.
The driving unit 602 of this embodiment determines if the previous and current original frame data F(n−1) and F(n) are within the predetermined range when the frequency of the output frame data SO(n) is doubled. If so, the driving unit 602 outputs the first current overdrive frame data SOD1(n) as the output frame data SO(n) during both the frame periods TS1′(n) and TS2′(n). As a result, even when the frequency of the output frame data SO(n) is twice as large as the frequency of the original frame data F(n), the time that the overdrive voltage corresponding to the output frame data SO(n) remains on the pixel electrode is prolonged in the case of the previous and the current original frame data F(n−1) and F(n) within the predetermined range. Thus, the issue of a pixel not being able to reach a desired brightness due to long reaction time of the liquid crystal molecules in the regions 102 and 104 in
In the described embodiments, the memories 2023, 4023 and 6023 can be non-volatile memories such as electrically erasable read only memories (EEROM) or flash memories, for example. In the first embodiment, the memory 2023 is for storing the first look-up table and the second look-up table. In the second and the third embodiments, the memories 4023 and 6023 are for storing respective look-up tables.
In the above example embodiments, the frequency of the output frame data SO(n) is twice as high as the frequency of the current original frame data F(n). However, the operation of the driving units 202, 402 and 602 can be extended to other frequencies of the output frame data. The buffers 2022, 4022 and 6022 can be synchronous dynamic random access memory buffers (SDRAM buffer), for example.
In the first embodiment, the first current overdrive frame data SOD1(n) and the second current overdrive frame data SOD2(n) can be the same (or substantially the same) or different. For example, the first current overdrive frame data SOD1(n) can be a low driving overdrive frame data. In other words, the gray level value of the first current overdrive frame data SOD1(n) can be less than that of the second current overdrive frame data SOD2(n).
The driving unit of some embodiments the present invention provides two overdrive frame data during one frame period. Alternatively, the driving unit selectively provides two overdrive frame data during one frame period. The time that the overdrive voltage corresponding to the output frame data SO(n) remains on the pixel electrode is prolonged in some embodiments. As a result, the reaction speed of liquid crystal molecules is increased for the data corresponding to all the gray level values when the refresh frequency is doubled. The frame can be displayed quickly and correctly, and the display quality is improved.
While the invention has been disclosed with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover such modifications and variations as fall within the true spirit and scope of the invention.
Number | Date | Country | Kind |
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95127862 | Jul 2006 | TW | national |