This application claims the priority benefit of Taiwan application serial no. 106110491, filed on Mar. 29, 2017. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
The invention relates to a driving technology, and more particularly, to a driving method for a display panel.
The increasing progresses of the display technology bring great conveniences to people's daily lives, in which flat panel displays (FPDs) have become the main stream products due to the characteristics of being light and thin. In various FPDs, liquid crystal displays (LCDs) are widely used because of the advantages of high space utility rate, low power consumption, free of radiation, low electromagnetic interference, and the like.
In response to the requirement for saving power, the refresh rate of display apparatuses in some cases may be reduced to 30 Hz or lower; that is, the pixels of the display panel may not perform the screen refreshing function within a certain period of time. At this time, the gate voltages of the transistors in the pixels may, within this period of time, stay at a certain level. If said gate voltages of the transistors stay at the same level for a long time, the transistors may encounter stress, which deteriorates the display quality of the display panel. Therefore, said issue of stress need be resolved to improve the display quality of the display panel.
The invention provides a driving method for a display panel, and the driving method is capable of restraining the aging effects of the switch devices in the pixel circuit.
In an embodiment of the invention, a driving method adapted for a display panel is provided. The display panel has a plurality of pixel circuits arranged in an array, and each of the pixel circuits includes at least one first switch and a second switch serially coupled to each other. The driving method includes following steps. A first driving signal is received during an update period through a control terminal of the at least one first switch of each of the pixel circuits, such that the at least one first switch of each of the pixel circuits is continuously turned on during the update period. A second driving signal is sequentially received during the update period through a control terminal of the second switch of each of the pixel circuits.
According to an embodiment of the invention, the driving method further includes a step of periodically receiving a plurality of first pulse signals during a waiting period through the control terminal of the second switch of each of the pixel circuits, wherein the first pulse signals have a first pulse width, and the first pulse signals have a first high-level voltage and a first low-level voltage.
According to an embodiment of the invention, the step of periodically receiving the second driving signal during the update period through the control terminal of the second switch of each of the pixel circuits further includes: adjusting at least one of the first high-level voltage and the first low-level voltage of the first pulse signals.
According to an embodiment of the invention, a first time interval exists between the control terminal of the second switch of each of the pixel circuits during the waiting period, so as to sequentially receive the first pulse signals.
According to an embodiment of the invention, a second time interval exists between the control terminal of the second switch of each of the pixel circuits in odd rows and the control terminal of the second switch of each of the pixel circuits in even rows, so as to alternately receive the first pulse signals.
According to an embodiment of the invention, the control terminal of the second switch of each of the pixel circuits simultaneously receives the first pulse signals during the waiting period.
According to an embodiment of the invention, the driving method further includes following steps. Plural second pulse signals are received during the waiting period through the control terminal of the at least one first switch of each of the pixel circuits, wherein the pixel circuits receive the second pulse signals and the first pulse signals at different times, and a second time interval exists between the time at which the first pulse signals are received by the pixel circuits and the time at which the second pulse signals are received by at least one of the pixel circuits.
According to an embodiment of the invention, the second pulse signals have a second high-level voltage and a second low-level voltage, and the step of receiving the second pulse signals during the waiting period through the control terminal of the at least one first switch of each of the pixel circuits includes: adjusting at least one of the second high-level voltage and the second low-level voltage of the second pulse signals.
According to an embodiment of the invention, the at least one first switch of each of the pixel circuits of the display panel comprises two first switches, one of the two first switches, the second switch, and the other of the two first switches are sequentially coupled in series, and the control terminal of one of the two first switches is coupled to the control terminal of the other of the two first switches.
According to an embodiment of the invention, a screen refresh rate of the display panel is smaller than or equal to 30 Hz.
In view of the above, the driving method for the display panel provided herein is able to effectively prevent the switch devices of the pixel circuits from staying at certain bias level for a long time and further prevent the aging effects caused by the accumulated bias stress of the switch devices.
To make the above features and advantages of the invention more comprehensible, several embodiments accompanied with drawings are described in detail as follows.
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.
The following will describe some embodiments as examples of the invention. However, it should be noted that the invention is not limited to the disclosed embodiments. Moreover, some embodiments may be combined where appropriate. The term “couple” used throughout this specification (including the claims) may refer to any direct or indirect connection means. For example, if it is described that the first device is coupled to the second device, it should be understood that the first device may be directly connected to the second device or indirectly connected to the second device through other devices or certain connection means. In addition, the term “signal” may refer to at least one current, voltage, charge, temperature, data, or one or more signals.
Here, the timing controller 110 is configured to receive an operating voltage VDD and enable the gate driving circuit 120, the source driving circuit 130, and the switch driving circuit 140. The switch driving circuit 140 outputs first driving signals to each pixel circuit P in the display panel 150 through the common gate signal lines Gc. The gate driving circuit 120 outputs a plurality of second pulse signals to each pixel circuit P in the display panel 150 through the gate signal lines G1-Gm, and m is a positive integer greater than 0. The source driving circuit 130 outputs a plurality of frame signals to each pixel circuit P in the display panel 150 through the source signal lines S1-Sn, and n is a positive integer greater than 0. In the present embodiment, the display panel 150 may be operated at a frequency with the screen refresh rate smaller than or equal to 30 Hz; however, the invention is not limited thereto.
Two ways to implement the pixel circuits in the display panel are explained hereinafter with reference to
In the present embodiment, a first terminal of the first switch M1 is coupled to the source signal line Sn. A control terminal of the first switch M1 is coupled to the common gate signal line Gc. A second terminal of the first switch M1 is coupled to a first terminal of the second switch M2. A control terminal of the second switch M2 is coupled to the gate signal line Gm. A second terminal of the second switch M2 is coupled to the other first switch M1′. A control terminal of the other first switch M1′ is also coupled to the common gate signal line Gc. One terminal at which the storage circuit Cst and the liquid crystal capacitor Clc are serially coupled is coupled to a second terminal of the other first switch M1′, and the other terminal at which the storage circuit Cst and the liquid crystal capacitor Clc are serially coupled is coupled to a ground terminal VCOM. In the present embodiment, the first terminal of the first switch M1 may receive a frame signal through the source signal line Sn. The control terminals of the first switches M1 and M1′ may receive the first pulse signals through the common gate signal line Gc, respectively. The control terminal of the second switch M2 may receive the second pulse signals through the gate signal line Gm.
During the update period P1, the control terminals of the first switches M1 and M1′ of each pixel circuit P of the display panel 150 may receive the first driving signal 410 through the common gate signal line Gc, such that the first switches M1 and M1′ of each pixel circuit P are continuously turned on during the update period P1. Besides, the control terminals of the second switches M2 of the pixel circuits P in each row may sequentially receive a plurality of second pulse signals 421, 422, and 423 through the gate signal lines G1, G2, and G3. Namely, in the update period P1, each pixel circuit P of the display panel 150 may perform the writing operation of the frame signal FS by sequentially receiving the driving signal through its second switch M2. During the waiting period P2, no signal is received by the control terminals of the first switches M1 and M1′ and the second switches M2 of the pixel circuits P of the display panel 150. Additionally, during the non-frame-writing period FP2, the display panel 150 may receive the same pulse signal waveforms as those received in the frame-writing period FP1, which should however not be construed as a limitation to the invention.
Compared to the previous embodiment, the present embodiment discloses that the control terminals of the second switches M2 of the pixel circuits P in each row of the display panel 150 sequentially and periodically receive the first pulse signals 531, 532, and 533 during the waiting period P2. For instance, the pulse width W1 of the first pulse signals 531, 532, and 533 may be 0.5 ms, for instance, and the time interval T1 among the first pulse signals 531, 532, and 533 is 1.5 ms, for instance. However, the invention is not limited thereto. Additionally, during the non-frame-writing period FP2, the display panel 150 may receive the same driving signal waveform and the same pulse signal waveforms as those received in the frame-writing period FP1, which should however not be construed as a limitation to the invention.
Compared to the previous embodiment, the present embodiment discloses that the control terminals of the second switches M2 of the pixel circuits P in odd rows and in even rows of the display panel 150 alternately and periodically receive the first pulse signals 631, 632, and 633 respectively at the time interval T1 during the waiting period P2. For instance, the pulse width W1 of the first pulse signals 631, 632, and 633 may be 0.5 ms, for instance, and the time interval among the first pulse signals 531, 532, and 533 is 1.5 ms, for instance. Additionally, during the non-frame-writing period FP2, the display panel 150 may receive the same driving signal waveform and the same pulse signal waveforms as those received in the frame-writing period FP1, which should however not be construed as a limitation to the invention.
Compared to the previous embodiment, the present embodiment discloses that the control terminals of the second switches M2 of the pixel circuits P in odd rows and in even rows of the display panel 150 simultaneously and periodically receive the first pulse signals 731, 732, and 733 during the waiting period P2. Additionally, during the non-frame-writing period FP2, the display panel 150 may receive the same driving signal waveform and the same pulse signal waveforms as those received in the frame-writing period FP1, which should however not be construed as a limitation to the invention.
Compared to the previous embodiment, the present embodiment discloses that the control terminals of the second switches M2 of the pixel circuits P in each row of the display panel 150 sequentially and periodically receive the first pulse signals 831, 832, and 833 during the waiting period P2. For instance, the pulse width W1 of the first pulse signals 831, 832, and 833 may be 0.5 ms, for instance, and the time interval T1 among the first pulse signals 831, 832, and 833 is 1.5 ms, for instance. However, the invention is not limited thereto.
Compared to the previous embodiment, the present embodiment discloses that the first switches M1 and M1′ of each of the pixel circuits P of the display panel 150 periodically receive the second pulse signals 840 during the waiting period P2. The pulse width W2 of the second pulse signals 840 may be the same as or different from the pulse width W1, for instance, and the time interval T2 may exist between the second pulse signals 840 and the first pulse signal 831, for instance; however, the invention is not limited thereto. Additionally, during the non-frame-writing period FP2, the display panel 150 may receive the same driving signal waveform and the same pulse signal waveforms as those received in the frame-writing period FP1, which should however not be construed as a limitation to the invention.
Compared to the previous embodiment, the present embodiment discloses that the control terminals of the second switches M2 of the pixel circuits P in odd rows and in even rows of the display panel 150 alternately and periodically receive the first pulse signals 931, 932, and 933 respectively at the time interval T1 during the waiting period P2. For instance, the pulse width W1 of the first pulse signals 931, 932, and 933 may be 0.5 ms, for instance, and the time interval T1 among the first pulse signals 931, 932, and 933 is 1.5 ms, for instance. However, the invention is not limited thereto.
Compared to the previous embodiment, the present embodiment discloses that the first switches M1 and M1′ of each of the pixel circuits P of the display panel 150 periodically receive the second pulse signals 940 during the waiting period P2. The pulse width W2 of the second pulse signals 940 may be the same as or different from the pulse width W1, for instance, and the time interval T2 may exist between the second pulse signals 940 and the first pulse signal 931, for instance; however, the invention is not limited thereto. Additionally, during the non-frame-writing period FP2, the display panel 150 may receive the same driving signal waveform and the same pulse signal waveforms as those received in the frame-writing period FP1, which should however not be construed as a limitation to the invention.
Compared to the previous embodiment, the present embodiment discloses that the control terminals of the second switches M2 of the pixel circuits P in odd rows and in even rows of the display panel 150 simultaneously and periodically receive the first pulse signals 1031, 1032, and 1033 during the waiting period P2. For instance, the pulse width W1 of the first pulse signals 1031, 1032, and 1033 may be 0.5 ms, for instance.
Compared to the previous embodiment, the present embodiment discloses that the first switches M1 and M1′ of each of the pixel circuits P of the display panel 150 periodically receive the second pulse signals 1040 during the waiting period P2. The pulse width W2 of the second pulse signals 1040 may be the same as or different from the pulse width W1, for instance, and the time interval T2 may exist between the second pulse signals 1040 and the first pulse signal 1031, for instance; however, the invention is not limited thereto. Additionally, in the present embodiment, during the non-frame-writing period FP2, the display panel 150 may receive the same driving signal waveform and the same pulse signal waveforms as those received in the frame-writing period FP1, which should however not be construed as a limitation to the invention.
The pixel circuit P shown in
The first pulse signals provided in the above embodiments have a first high-level voltage and a first low-level voltage, and the second pulse signals have a second high-level voltage and a second low-level voltage. In an embodiment, the pixel circuit may further include a multiplexer or other circuit devices, and the high-level voltages and the low-level voltages of the pulse signals may be adjusted according to not only the pulse signal waveforms shown in
Other ways to implement the driving method of the display panel can be understood sufficiently from the teaching, suggestion, and descriptions of the embodiments illustrated in
To sum up, the driving method for the display panel is capable of effectively restraining the aging effects of the switch devices in each pixel circuit when the display panel is being operated in a low-frequency mode (e.g., the operating frequency is equal to or less than 30 Hz). That is, each pixel circuit of the display panel may periodically provide the pulse signals to the switch devices during the waiting period, so as to effectively prevent the switch devices from staying at a certain bias level for a long time and further restrain the aging effects of the TFT caused by the bias stress.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the invention. In view of the foregoing, it should be mentioned that the invention covers modifications and variations of this disclosure provided that they fall within the scope of the following claims and their equivalents.
Number | Date | Country | Kind |
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106110491 | Mar 2017 | TW | national |