This application claims priority to Taiwan Application Serial Number 112147532, filed Dec. 6, 2023, which is herein incorporated by reference.
The present disclosure relates to a driving method of a display device, and more particularly to a driving method of a display device for reducing abnormality in a display screen.
Some conventional display devices mainly include a pixel display region and a scan driving circuit. The pixel display region is composed of a plurality of pixel circuits arranged in an array, and each pixel circuit includes a light emitting element (e.g., a light emitting diode). The light emitting element emits brightness required for a display screen according to a driving current flowing through it. During each frame time, the scan driving circuit generates multiple scanning signals and light emitting control signals in a time-division manner to turn on pixel circuits of each column in the pixel display region, so that data information is sequentially written into each pixel circuit in the pixel display region.
However, in common signal lines in the pixel display region, there are inevitably parasitic capacitances and stray capacitances between electrodes, which cause signal coupling effects when data information is written into the pixel circuits, thereby affecting stability of the signals and a light emitting interval of the pixel circuits. Such signal coupling effects cause abnormal phenomena such as flicker, uneven brightness, cross talk, and image sticking in the display screen of the display device.
Therefore, the present disclosure provides a driving method of a display device, used for driving at least one pixel circuit in a plurality of columns, in which each of the at least one pixel circuit has at least one light emitting element, and the driving method includes: executing a plurality of driving sequences during a frame time to sequentially drive the at least one pixel circuit in the columns, in which executing each of the driving sequences includes: inputting at least one data pulse signal to write data information into the at least one pixel circuit of a corresponding one of the columns; and inputting a light emitting control pulse signal to the at least one pixel circuit of the corresponding one of the columns, in which the light emitting control pulse signal includes at least one light emitting control pulse within the frame time; in which the at least one data pulse signal and the at least one light emitting control pulse signal in each of the driving sequences are alternately inputted to the at least one pixel circuit of the corresponding columns, so that the at least one pixel circuit in each of the columns does not receive the at least one data pulse signal and the at least one light emitting control pulse at the same time.
According to an embodiment of the present disclosure, the driving sequences comprises a first driving sequence and a second driving sequence, before executing the second driving sequence, the at least one data pulse signal and the at least one light emitting control pulse in the first driving sequence are completely inputted to the at least one pixel circuit of the corresponding one of the columns.
According to an embodiment of the present disclosure, the at least one data pulse signal and the at least one light emitting control pulse in each of the driving sequences are completely inputted within a scanning period, and the scanning period is the time for driving the at least one pixel circuit in one of the columns.
According to an embodiment of the present disclosure, the at least one pixel circuit in the columns further includes a common line electrically connected to the at least one pixel circuit in each of the columns to generate a common signal to the at least one pixel circuit in each of the columns.
According to an embodiment of the present disclosure, the at least one light emitting control pulse and the common signal in each of the driving sequences are alternately inputted to corresponding one of the at least one pixel circuit.
According to an embodiment of the present disclosure, the driving method further includes providing at least one reset signal to the at least one pixel circuit in each of the columns within the frame time through a time pulse signal.
According to an embodiment of the present disclosure, the at least one light emitting control pulse in each of the driving sequences and the at least one data pulse signal in other of the driving sequences are alternately inputted to the corresponding one of the at least one pixel circuit during the frame time.
According to an embodiment of the present disclosure, the at least one light emitting element is a micro light emitting diode.
According to an embodiment of the present disclosure, the light emitting control pulse has a high logic level.
According to an embodiment of the present disclosure, the at least one pixel circuit comprises a plurality of N-type transistors, and the plurality of N-type transistors are turned on based on the high logic level of the light emitting control pulse.
According to an embodiment of the present disclosure, the light emitting control pulse has a low logic level.
According to an embodiment of the present disclosure, the at least one pixel circuit comprises a plurality of P-type transistors, and the plurality of P-type transistors are turned on based on the low logic level of the light emitting control pulse.
According to an embodiment of the present disclosure, supply timings of the at least one data pulse signal and the at least one light emitting control pulse signal are controlled by a timing controller.
According to an embodiment of the present disclosure, in the at least one pixel circuit, a path of a driving current flowing through the at least one light emitting element comprises at least two transistors.
According to an embodiment of the present disclosure, the driving method further comprises providing at least one scanning signal to the at least one pixel circuit in each of the plurality of columns within the frame time.
The present disclosure provides a driving method of a display device, used for driving at least one pixel circuit in a plurality of columns, in which each of the at least one pixel circuit has at least one light emitting element, and the driving method includes: executing a plurality of driving sequences during a frame time to sequentially drive the at least one pixel circuit in the columns, in which executing each of the driving sequences includes: inputting at least one data pulse signal to write data information into the at least one pixel circuit of a corresponding one of the columns; and inputting a light emitting control pulse signal to the at least one pixel circuit of the corresponding one of the columns, in which the light emitting control pulse signal includes at least one light emitting control pulse within the frame time; in which the at least one light emitting control pulse in each of the plurality of driving sequences and the at least one data pulse signal in other of the plurality of driving sequences are alternately inputted to corresponding one of the at least one pixel circuit during the frame time.
In order to make the above and other objects, features, advantages and embodiments of the present disclosure easier to understand, the accompanying drawings are described as follows:
The following disclosure provides many different embodiments or examples for implementing different features of the provided disclosure. The embodiments of components and configurations described below are examples only and are not intended to be limiting. In addition, for the purpose of simplification and clarity, the present disclosure repeats reference numerals and/or numbers in each example in the present disclosure, and this repetition does not in itself limit the relationship between various embodiments and/or components discussed.
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In all pixel circuits of the display device, there is usually a common line (e.g., a reference voltage or a reset voltage). In order to prevent parasitic capacitive and stray capacitive coupling effects of the common line from affecting picture quality of the display device, main technical features of the driving method 100 are as follows: (1) making a data pulse signal and a light emitting control signal in each driving sequence alternately input to each pixel circuit in a same column; (2) making the light emitting control signal received by the pixel circuit of each column are interleaved with data pulse signals received by pixel circuits of other columns.
In this way, a light emitting period and a data writing period of each pixel circuit do not overlap with each other, thus avoiding the coupling effects caused by the presence of parasitic capacitance and stray capacitance in the common line when the data pulse signal is written into the pixel circuit. In following examples, the driving method 100 of the present disclosure is explained in conjunction with a pixel circuit 200 of
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In an embodiment of the present disclosure, the light emitting diode LED adopts a micro LED (μLED), and the driving method 100 adopts pulse width modulation (PWM) to control light emitting of the light emitting diode LED. Specifically, when the driving method 100 of the present disclosure is used to drive the micro LED, the micro LED is controlled to have a shorter light emitting period, that is, a duty of the light emitting control signal is smaller. In this way, the micro LED may be operated with higher luminous efficiency during a period of larger instantaneous current. In addition, one frame time may have one or more light emitting periods (e.g., only one light emitting control pulse or multiple light emitting control pulses) to drive the micro LED to emit light during the one or more light emitting periods, but the disclosure is not limited thereto.
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A first terminal of the transistor T4 is coupled to the transistor T6 and the transistor T5, and a second terminal of the transistor T4 is coupled to the transistor T3 and the transistor T1. A first terminal of the transistor T5 is coupled to the storage capacitor CST and the control terminal of the transistor T5, and a second terminal of the transistor T3 is coupled to the transistor T4 and the transistor T1. A first terminal of the transistor T7 is coupled to the storage capacitor CST and the transistor T2, and a second terminal of the transistor T7 receives the data pulse signal VDATA. Control terminals of the transistors T3, T4 and T7 receive the scanning signal S2[N].
A first terminal of the transistor T2 receives a reference signal VREF, and a second terminal of the transistor T2 is coupled to the transistor T7 and the storage capacitor CST, and a control terminal of the transistor T2 receives the light emitting control signal EM[N]. A first terminal of the transistor T1 receives the reference signal VREF, and a second terminal of the transistor T1 is coupled to the transistor T3 and the transistor T4, and a control terminal of the transistor T1 receives the scanning signal S1[N]. Among them, N represents a number of columns, so EM[N] represents the light emitting control signal of the Nth column, and S1[N] represents a first scanning signal of the Nth column, and S2[N] represents a second scanning signal of the Nth column.
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In the interval t2, the scanning signal S1[N] is at a low voltage level (equivalent to the low logic level), and the scanning signal S2[N] is at the low voltage level (equivalent to the low logic level), and the light emitting control signal EM[N] is at a high voltage level (equivalent to the high logic level), so that the transistors T1, T3, T4 and T7 are turned on according to the low voltage levels, and the transistors T2 and T6 are turned off according to the high voltage level. The conduction of the transistor T7 causes the data pulse signal VDATA to be inputted to a node N2, which is the first terminal (i.e., the electrode) of the storage capacitor CST. The second terminal (i.e., the electrode) of the storage capacitor CST receives the reference signal VREF with the same potential as the node N1 due to the conduction of the transistor T3 and the transistor T4, so that the control terminal of the transistor T5 is turned on according to the reference signal VREF.
The interval t3 is a writing period of the data pulse signal VDATA of the pixel circuit 200, in which the scanning signal S1[N] is at a high voltage level, and the scanning signal S2[N] is at a low voltage level, and the light emitting control signal EM[N] is at a high voltage level, which causes the transistor T3, T4 and T7 to be turned on according to the low voltage level, while the transistor T1, T2 and T6 are turned off according to the high voltage levels. The conduction of the transistor T7 maintains the potential of the first terminal (node N1) of the storage capacitor CST at the data pulse signal VDATA, and the potential of the second terminal of the storage capacitor CST is maintained at VDD−Vth5, so that the transistor T5 can continue to be turned on in the interval t3. Therefore, the voltage difference across the storage capacitor CST is (VDD−Vth5)−VDATA.
In the interval t4, the scanning signal S1[N] is at a high voltage level, and the scanning signal S2[N] is at a high voltage level, and the light emitting control signal EM[N] is at a low voltage level, so that the transistor T2 and the transistor T6 are turned on according to the low voltage level, and the transistor T1, the transistor T3, the transistor T4 and the transistor T7 are turned off according to the high voltage levels. The conduction of transistor T2 causes the first terminal (node N2) of the storage capacitor CST to receive the reference signal VREF, and the potential of the second terminal of the storage capacitor CST is (VDD−Vth5)−VDATA+VREF, so the transistor T5 can continue to be turned on in the interval t4. The conduction of the transistor T6 enables the driving current ILED to flow through to the light emitting diode LED, and controls the light emitting diode LED to emit a required brightness. Among them, the driving current ILED can be obtained by Equation (1):
Among them, Vth5 is a critical voltage value of transistor T5. Equation (1) is a calculation formula for the driving current ILED, and is known to those skilled in the art, so it will not be described detail herein.
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As such, it is possible to prevent the signal jitter of the common line (reference signal VREF) from affecting the light emitting period of each pixel circuit during the writing of the data pulse signal VDATA in each driving sequences, and solve the abnormal phenomena such as flicker, uneven brightness, cross talk, or image sticking in the screen of the display device caused by the capacitive coupling effects. Although not shown in the figures, in some embodiments, the driving method 100 further includes providing at least one reset signal to the pixel circuit in each column through a time pulse signal. Among them, the supply timings of the time pulse signal, the data pulse signal, the light emitting control signal, and the reset signal can be controlled through a timing controller.
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Under the conditions of the same grayscale (L127), brightness (151 nits) and frequency (15 Hz), the flicker value in
According to the driving method of the display device of the present disclosure, the data pulse signal and the light emitting control signal in each driving sequence are alternately inputted to each pixel circuit in the same column, and the light emitting control signal received by the pixel circuit of each column is interleaved with the data pulse signals received by the pixel circuits of other columns, which can effectively prevent the signal jitter of the common line when the data pulse signal is written into the pixel circuit, and thus does not affect the light emitting period of each pixel circuit. In this way, through the driving method of the display device of the present disclosure, abnormal phenomena such as flicker, uneven brightness, cross talk, or image sticking in the display screen caused by the capacitive coupling effects can be solved.
Although the present disclosure has been disclosed as above in embodiments, the embodiments are not intended to limit the present disclosure, and those of ordinary skill in the art may make some changes and embellishments within the spirit and scope of the present disclosure, therefore, the scope of protection of the present disclosure shall be defined in the attached claims.
Number | Date | Country | Kind |
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112147532 | Dec 2023 | TW | national |