TWI868912B - Brightness control method, gate drive circuit and information processing device - Google Patents

Abstract

The present invention mainly discloses a brightness control method, which is performed by a gate drive unit and includes the following steps: determining and adjusting the number of pulses of a light-emitting control signal according to a signal cycle and a duty cycle, so that the light-emitting control signal has P pulses in a frame display cycle; and providing the light-emitting control signal to a light-emitting control element in a pixel circuit. When the brightness control method of the present invention is applied, the number of pulses contained in the light-emitting control signal is not limited to ²ⁿ , so that the EM signal generation circuit of the gate drive unit can be simplified in design, thereby greatly reducing the circuit area. In addition, if necessary, the number of pulses of the luminous control signal in one display cycle can be expanded to 150-300 pulses without being limited by the quantity threshold.

Description

Brightness control method, gate drive circuit and information processing device

The present invention relates to the technical field of OLED and Micro-LED displays, and in particular to a brightness control method for a gate drive circuit.

It is known that flat panel displays include non-self-luminous flat panel displays and self-luminous flat panel displays, wherein liquid crystal displays are a type of non-self-luminous flat panel displays that have been used for a long time, while organic light-emitting diode (OLED) displays and light-emitting diode (LED) displays are self-luminous flat panel displays that are currently in mainstream applications.

FIG1 is a block diagram of a known OLED display. As shown in FIG1 , the known OLED display 1a mainly includes: an OLED display panel 11a, a timing controller 120a, a source drive circuit (or display drive circuit) 121a, and a gate drive circuit 122a, wherein the OLED display panel 11a includes a plurality of pixel circuits 111a and a plurality of sub-pixels (i.e., OLED elements) 112a, and the source drive circuit 121a provides display data signals VDATA to each pixel circuit 111a through a plurality of source lines. On the other hand, the gate driving circuit 122a includes a plurality of gate driving units 12Ga, and each of the gate driving units 12Ga includes at least one shift register and an EM signal generating circuit for respectively providing at least one scanning signal (or gate control signal) and a light-emitting control signal to the pixel circuit 111a.

Electronic engineers familiar with the design of pixel circuits know that the pixel circuit 111a includes a plurality of semiconductor switch elements and at least one storage capacitor, wherein the semiconductor switch element can be a TFT element or a MOSFET element. For example, the structure of the pixel circuit 111 is 6T1C, 7T1C, 7T2C, 8T1C, or 8T2C. To explain in more detail, among the plurality of semiconductor switch elements, there is one semiconductor switch element as a driving element, there is one semiconductor switch element as a display data writing element coupled, and there is one semiconductor switch element as a light-emitting control element.

FIG2 is a diagram of a driving element M1a, a display data writing element M2a, a storage capacitor C1a, and a light-emitting control element M3a included in the pixel circuit 111a shown in FIG1. As shown in FIG2, the driving element M1a, the display data writing element M2a, and the light-emitting control element M3a can all be a TFT element or a MOSFET element, and all have a gate terminal, a first element electrical terminal, and a second element electrical terminal. To explain in more detail, the second element electrical terminal of the driving element M1a is coupled to the anode terminal of the OLED element 112a, and its gate terminal is coupled to the first terminal of the storage capacitor C1a. On the other hand, the gate terminal, the first device electrical terminal and the second device electrical terminal of the display data writing element M2a are respectively coupled to a gate control signal G<n>, a display data signal VDATA and the gate terminal of the driving element M1a. In addition, the gate terminal, the first device electrical terminal and the second device electrical terminal of the luminescence control element M3a are respectively coupled to a luminescence control signal EM<n>, a first driving voltage ELVDD and the first device electrical terminal of the driving element M1a.

FIG3 is a timing diagram of the gate control signal and the light-emitting control signal shown in FIG2. As shown in FIG2 and FIG3, in a data writing time interval of a frame display cycle In the embodiment of FIG. 1 , the gate control signal G<n> is at a low level and the luminance modulation signal EM<n> is at a high level, so the luminance modulation element M3a is turned off and the display data writing element M2a is turned on, so that the data voltage of the display data signal VDATA is written into the storage capacitor C1a. Then, in a luminance time interval of a frame display cycle, Afterwards, the gate control signal G<n> turns to a high level and the luminance modulation signal EM<n> turns to a low level, so the display data writing element M2a is turned off and the luminance modulation element M3a and the driving element M1a are both turned on, so that the OLED element 112a is driven by voltage to emit light.

Practical experience shows that when the frame rate is switched to a lower frequency (such as 30Hz, 10Hz), the low-level width and high-level width of the luminous modulation signal EM<n> are also lengthened synchronously because the time of a frame display cycle becomes longer. In this case, the human eye can easily observe the flickering feeling, which makes the screen flickering phenomenon more serious. Therefore, it is necessary to increase the number of pulses and shorten the low-level width and high-level width time to improve the flickering feeling.

In summary, it is necessary to consider developing and designing a new pulse quantity (brightness) control method for use in the gate drive circuit 122a, so that each of the light controllers in the gate drive circuit 122a can generate a light control signal EM＜n＞ according to the current frame rate, thereby shortening the absolute time of the low-level width and the high-level width and eliminating the flickering phenomenon.

From the above description, it can be seen that a new pixel driving control method is urgently needed in this field.

The main purpose of the present invention is to provide a (brightness) pulse quantity control method, which is performed by a gate drive circuit, wherein the gate drive circuit is integrated in a display device, and the display device also includes a source drive circuit, a timing controller, and a display panel including a plurality of pixel circuits and a plurality of sub-pixels. When the brightness control method of the present invention is applied, the number of pulses contained in the luminous control signal is not limited to ²ⁿ , so that the EM signal generation circuit of the gate drive unit can be simplified in design, thereby greatly reducing the circuit area. In addition, if necessary, the number of pulses in the luminance modulation signal within a frame display cycle can also be expanded to 150-300 pulses, without being limited by the quantity threshold. Furthermore, experimental data show that as the number of pulses increases, the luminance modulation signal exhibits a better suppression effect on the flickering phenomenon of the display device.

To achieve the above-mentioned purpose, the present invention proposes an embodiment of the brightness control method, which is executed by a gate drive unit and includes the following steps: Determine and adjust the number of pulses of a light-emitting control signal according to a signal cycle and a duty cycle, so that the light-emitting control signal has P pulses in a frame display cycle; P is a positive integer; and Provide the light-emitting control signal to a light-emitting control element in a pixel circuit.

In a feasible embodiment, the pixel circuit is any one selected from the group consisting of an OLED pixel circuit, a Micro-LED pixel circuit and a QLED pixel circuit.

In another feasible embodiment, the pixel circuit includes a plurality of semiconductor switch elements and at least one storage capacitor, and the semiconductor switch element is any one selected from the group consisting of TFT elements and MOSFET elements.

In one embodiment, the gate driving unit determines the pulse width of the luminance modulation signal using the following formula (1): EM _PW =T'×D…………………………(1); wherein EM _PW is the pulse width of the luminance modulation signal, T' is the signal period, and D is the duty cycle.

To achieve the above-mentioned purpose, the present invention also proposes an embodiment of a gate drive circuit, which is integrated in a display device, wherein the display device also includes a source drive circuit, a timing controller, and a display panel including a plurality of pixel circuits and a plurality of sub-pixels; the gate drive circuit executes a brightness control method to perform a pulse quantity adjustment operation on a light-emitting control signal, and the brightness control method includes the following steps: Determine and adjust the number of pulses of the light-emitting control signal according to a signal cycle and a duty cycle, so that the light-emitting control signal has P pulses in a frame display cycle; P is a positive integer; and The light-emitting control signal is provided to a light-emitting control element in a pixel circuit.

In a feasible embodiment, the pixel circuit is any one selected from the group consisting of an OLED pixel circuit, a Micro-LED pixel circuit and a QLED pixel circuit.

In another feasible embodiment, the pixel circuit includes a plurality of semiconductor switch elements and at least one storage capacitor, and the semiconductor switch element is any one selected from the group consisting of TFT elements and MOSFET elements.

In one embodiment, the gate driving unit determines the pulse width of the luminance modulation signal using the following formula (1): EM _PW =T'×D…………………………(1); wherein EM _PW is the pulse width of the luminance modulation signal, T' is the signal period, and D is the duty cycle.

Furthermore, the present invention also provides an embodiment of an information processing device, which is characterized in that it has a display device, and the display device includes the gate drive circuit of the present invention as described above.

In one embodiment, the information processing device is an electronic device selected from the group consisting of an OLED display device, a Micro-LED display device, a QLED display device, a smart TV, a smart phone, a smart watch, a tablet computer, a laptop computer, an all-in-one computer, an in-vehicle entertainment system, a head-mounted display device, a video portal, a multimedia information display device, and a digital camera.

In order to enable the Review Committee to further understand the structure, features, purpose, and advantages of the present invention, the following are attached with drawings and detailed descriptions of preferred specific embodiments.

FIG4 is a block diagram of a display device including a gate drive circuit of the present invention. As shown in FIG4 , the display device 1 includes: a display panel 11, a timing controller 120, a source drive circuit 121, and a gate drive circuit 122 of the present invention, wherein the display panel 11 includes a plurality of pixel circuits 111 and a plurality of sub-pixels 112. For example, the display panel 11 is an OLED display panel, which includes a plurality of OLED pixel circuits and a plurality of OLED elements. In other feasible embodiments, the display panel 11 may also be a Micro-LED display panel or a QLED display panel, in which case the pixel circuit 111 is correspondingly a Micro-LED pixel circuit or a QLED pixel circuit.

Electronic engineers familiar with the design of pixel circuits know that the pixel circuit 111 includes a plurality of semiconductor switch elements and at least one storage capacitor, wherein the semiconductor switch element can be a thin film transistor (FTF) element or a metal oxide semiconductor field effect transistor (MOSFET) element. For example, the structure of the pixel circuit 111 is 6T1C, 7T1C, 7T2C, 8T1C, or 8T2C. To explain in more detail, among the plurality of semiconductor switch elements, there is one semiconductor switch element as a driving element, there is one semiconductor switch element as a display data writing element coupled, and there is one semiconductor switch element as a light-emitting control element.

FIG5 is a diagram of a driving element M1, a display data writing element M2, a storage capacitor C1, and a light-emitting control element M3 included in the pixel circuit 111 shown in FIG4. As shown in FIG5, the driving element M1, the display data writing element M2, and the light-emitting control element M3 can all be a TFT element or a MOSFET element, and all have a gate terminal, a first element electrical terminal, and a second element electrical terminal. To explain in more detail, the second element electrical terminal of the driving element M1 is coupled to an electrical terminal of the sub-pixel 112, and its gate terminal is coupled to the first terminal of the storage capacitor C1. On the other hand, the gate terminal, the first device electrical terminal and the second device electrical terminal of the display data writing element M2 are respectively coupled to a gate control signal G<n>, a display data signal VDATA and the gate terminal of the driving element M1. In addition, the gate terminal, the first device electrical terminal and the second device electrical terminal of the luminescence control element M3 are respectively coupled to a luminescence control signal EM<n>, a first driving voltage ELVDD and the first device electrical terminal of the driving element M1.

As shown in FIG4 , the source driver circuit 121 (also called display driver circuit) provides the display data signal VDATA to each pixel circuit 111 through a plurality of source lines. On the other hand, the gate driver circuit 122 includes a plurality of gate driver units 12G, and each gate driver unit 12G includes at least one shift register and an EM signal generating circuit, for providing at least one gate control signal G<n> (or scan signal) and a light modulation signal EM<n> to each pixel circuit 111, respectively.

In particular, the present invention proposes a brightness control method for the gate drive circuit 122 to perform, so that the gate drive unit 12G provides a light-emitting control signal EM<n> with a specified working timing to the corresponding pixel circuit 111. FIG. 6 is a flow chart of a brightness control method of the present invention. As shown in FIG. 5 and FIG. 6, the method flow first executes step S1: determining and adjusting the number of pulses of the light-emitting control signal EM<n> according to a signal cycle and a duty cycle, so that the light-emitting control signal EM<n> has P pulses within a frame display cycle; P is a positive integer. Next, the method flow executes step S2: providing the luminescence control signal EM<n> to a luminescence control element M3 in a pixel circuit 111.

In a feasible embodiment, the gate driving unit uses the following formula (i) to determine the pulse width of the light-emitting control signal: EM _PW = (T/2 ⁿ ) × D (i)

In the above formula (i), EM _PW is the pulse width of the luminance modulation signal EM<n>, T is a frame display period, and 2 ⁿ is the number of pulses of the luminance modulation signal EM<n> existing in a frame display period. FIG. 7 is a working timing diagram of multiple different luminance modulation signals EM<n>, and the following table (1) summarizes EM _PW , T, Pulses, and D of each luminance modulation signal EM<n>. Table (1) EM _PW (ms) T (ms) Pulses (#) D 16.6 33.2 2 ⁰ =1 0.5 8.3 33.2 2 ¹ =2 0.5 4.15 33.2 2 ² =4 0.5 2.08 33.2 2 ³ =8 0.5

The above formula (i) can be used to determine and adjust the number of pulses of the luminous control signal EM<n> according to a frame display cycle and a duty cycle, so that the luminous control signal EM<n> has P pulses within a frame display cycle. However, it can be found from Table (1) and FIG. 7 that the number of pulses is limited to ²ⁿ , where n is an integer. In addition, as the number of pulses increases, the EM signal generating circuit of each gate drive unit 12G also becomes large and complex, resulting in the circuit area of the gate drive unit 12G being forced to increase. As can be imagined, the gate driver circuit 122 includes a plurality of gate driver units 12G, so the increase in the circuit area will limit the application of the gate driver circuit 122 in a small-sized display device 1. On the contrary, without increasing the circuit area, the number of pulses that the EM signal generating circuit of the gate driver unit 12G can expand will be limited by a quantity threshold.

In another feasible embodiment, the gate driving unit uses the following formula (1) to determine the pulse width of the light modulation signal EM<n>: EM _PW = T' × D (1)

In the above formula (1), EM _PW is the pulse width of the luminous control signal EM<n>, T' is the signal period, and D is the duty cycle. FIG8 is a working timing diagram of a plurality of different luminous control signals EM<n>, and the following table (2) summarizes EM _PW , T, Pulses, and D of each luminous control signal EM<n>. Table (2) EM _PW (ms) T (ms) T' (ms) D Pulse (#) 6.225 33.2 12.45 0.5 ≒3 2.08 33.2 4.16 0.5 ≒8

The above formula (1) can be used to determine and adjust the number of pulses (Pulses) according to a signal period T' and a duty cycle D of the luminous control signal EM＜n＞, so that the luminous control signal EM＜n＞ has P pulses within a frame display period T. It can be found from Table (2) and Figure 8 that the number of pulses is not limited to ²ⁿ , so that the EM signal generation circuit in each gate drive unit 12G can be simplified in design, thereby greatly reducing the circuit surface area. In addition, if necessary, the number of pulses of the luminous control signal EM＜n＞ within a frame display period can also be expanded to 150~300 pulses, and will not be limited by the number threshold value. Furthermore, as shown in the experimental data of FIG. 9 , as the number of pulses increases, the light modulation signal exhibits a better suppression effect on the flickering phenomenon of the display device.

Thus, the above has completely and clearly described a brightness control method of the present invention; and, from the above, it can be known that the present invention has the following advantages:

(1) The present invention discloses a brightness control method, which is performed by a gate drive circuit, wherein the gate drive circuit is integrated into a display device, and the display device further includes a source drive circuit, a timing controller, and a display panel including a plurality of pixel circuits and a plurality of sub-pixels. When the brightness control method of the present invention is applied, the number of pulses contained in the luminous control signal is not limited to ²ⁿ , so that the EM signal generation circuit of the gate drive unit can be simplified in design, thereby greatly reducing the circuit area. In addition, if necessary, the number of pulses in the luminance modulation signal within a frame display cycle can also be expanded to 150-300 pulses, without being limited by the quantity threshold. Furthermore, experimental data show that as the number of pulses increases, the luminance modulation signal exhibits a better suppression effect on the flickering phenomenon of the display device.

(2) The present invention also discloses a gate driver circuit integrated in a display device, wherein the gate driver circuit executes the brightness control method of the present invention as described above, so that each gate driver unit provides a light control signal with a specified working sequence to its corresponding pixel circuit, thereby eliminating the flickering phenomenon.

(3) The present invention further discloses an information processing device, characterized in that it has a display device, and the display device includes the gate drive circuit of the present invention as described above. The information processing device is an electronic device selected from the group consisting of an OLED display device, a Micro-LED display device, a QLED display device, a smart TV, a smart phone, a smart watch, a tablet computer, a notebook computer, an all-in-one computer, an in-vehicle entertainment system, a head-mounted display device, a video door machine, a multimedia information display device, and a digital camera.

It must be emphasized that what is disclosed in the above-mentioned case is a preferred embodiment. Any partial changes or modifications that are derived from the technical ideas of this case and are easily inferred by people familiar with the art do not deviate from the scope of the patent rights of this case.

In summary, this case shows that its purpose, means and effects are very different from the known technology, and it is the first invention that is practical and indeed meets the patent requirements for invention. We sincerely request the review committee to examine this carefully and grant a patent as soon as possible to benefit the society. This is our utmost prayer.

1a: OLED display 11a: OLED display panel 111a: pixel circuit 112a: OLED element 120a: timing controller 121a: source drive circuit 122a: gate drive circuit 12Ga: gate drive unit M1a: drive element M2a: display data writing element M3a: light-emitting control element C1a: storage capacitor 1: display device 11: display panel 111: pixel circuit 112: sub-pixel 120: timing controller 121: source drive circuit 122: gate drive circuit 12G: gate drive unit M1: driving element M2: display data writing element M3: light-emitting control element C1: storage capacitor S1: determining and adjusting the number of pulses of a light-emitting control signal according to a signal cycle and a duty cycle, so that the light-emitting control signal has P pulses in a display cycle; P is a positive integer S2: providing the light-emitting control signal to a light-emitting control element in a pixel circuit

FIG. 1 is a block diagram of a known OLED display; FIG. 2 is a diagram of a driving element, a display data writing element, a storage capacitor, and a light-emitting control element included in the pixel circuit shown in FIG. 1; FIG. 3 is a working timing diagram of the gate control signal and the light-emitting control signal shown in FIG. 2; FIG. 4 is a block diagram of a display device including a gate driving circuit of the present invention; FIG. 5 is a driving element, a display data writing element, a storage capacitor, and a light-emitting control element included in the pixel circuit shown in FIG. 4; FIG. 6 is a flow chart of a brightness control method of the present invention; FIG. 7 is a working timing diagram of multiple different light-emitting control signals; FIG. 8 is a working timing diagram of multiple different light-emitting control signals; and Figure 9 is a data scatter plot of pulse quantity relative to flicker (dB).

S1: Determine and adjust the number of pulses of a light-emitting control signal according to a signal cycle and a duty cycle, so that the light-emitting control signal has P pulses in a frame display cycle; P is a positive integer

S2: Provide the light-emitting control signal to a light-emitting control element in a pixel circuit

Claims (8)

A brightness control method is performed by a gate driving unit and includes the following steps: determining and adjusting the number of pulses of a light-emitting control signal according to a signal period and a duty cycle so that the light-emitting control signal has P pulses within a frame display period; P is a positive integer; and providing the light-emitting control signal to a light-emitting control element in a pixel circuit; wherein the gate driving unit determines the width of the pulse of the light-emitting control signal using the following formula (1): EM _PW =T'×D...........................(1); wherein EM _PW is the width of the pulse of the light-emitting control signal, T' is the signal period, and D is the duty cycle. The brightness control method as described in claim 1, wherein the pixel circuit is selected from any one of the groups consisting of an OLED pixel circuit, a Micro-LED pixel circuit, and a QLED pixel circuit. The brightness control method as described in claim 1, wherein the pixel circuit includes a plurality of semiconductor switch elements and at least one storage capacitor, and the semiconductor switch element is any one selected from the group consisting of TFT elements and MOSFET elements. A gate drive circuit is integrated in a display device, wherein the display device further includes a source drive circuit, a timing controller, and a display panel including a plurality of pixel circuits and a plurality of sub-pixels; the gate drive circuit executes a brightness control method to perform a pulse quantity adjustment operation on a light-emitting control signal, and the brightness control method includes the following steps: The number of pulses of the light-emitting control signal is determined and adjusted according to a signal period and a duty cycle, so that the light-emitting control signal has P pulses within a frame display period; P is a positive integer; and the light-emitting control signal is provided to a light-emitting control element in a pixel circuit; wherein the gate drive circuit uses the following formula (1) to determine the width of the pulse of the light-emitting control signal: EM _PW =T'×D...........................(1); wherein EM _PW is the width of the pulse of the light-emitting control signal, T' is the signal period, and D is the duty cycle. The gate drive circuit as described in claim 4, wherein the pixel circuit is selected from any one of the group consisting of an OLED pixel circuit, a Micro-LED pixel circuit, and a QLED pixel circuit. A gate drive circuit as described in claim 4, wherein the pixel circuit includes a plurality of semiconductor switch elements and at least one storage capacitor, and the semiconductor switch element is any one selected from the group consisting of TFT elements and MOSFET elements. An information processing device, characterized in that it has a display device, and the display device includes a gate drive circuit as described in any one of claim 4 to claim 6. The information processing device as described in claim 7, wherein the information processing device is an electronic device selected from the group consisting of an OLED display device, a Micro-LED display device, a QLED display device, a smart TV, a smart phone, a smart watch, a tablet computer, a laptop computer, an all-in-one computer, an in-vehicle entertainment system, a head-mounted display device, a video portal, a multimedia information display device, and a digital camera.

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