Display panel

Abstract

A display panel. The display panel includes a plurality of pixel groups. Each pixel group includes a pulse width modulation control circuit and a plurality of sub-pixels. The pulse width modulation control circuit receives pulse width modulation data and a global light emission signal to provide a local light emission signal, wherein a pulse width of the local light emission signal is less than or equal to a pulse width of the global light emission signal. The plurality of sub-pixels individually have light emitting diodes, wherein the sub-pixels include a first sub-pixel that receives first pulse amplitude modulation data and the local light emission signal, wherein the first pulse amplitude modulation data determines a first drive current that flows through the light emitting diode of the first sub-pixel, and the local light emission signal determines a pass time of the first drive current that flows through the light emitting diode of the first sub-pixel.

Description

TECHNICAL FIELD

[0001] The present application relates to a display panel, and particularly relates to a display panel with active light emitting elements. BACKGROUND

[0002] With the increasing environmental awareness, energy saving, service life, color saturation and power quality have gradually become the factors considered by consumers when purchasing. At the same time, the rapid development of semiconductor technology and cost reduction have driven light emitting elements to become the mainstream of the future lighting and display market. Among them, organic light emitting diode (OLED) and micro light emitting diode (uLED) are the main elements used in self-luminous display panels at present.

[0003] However, the light emitting brightness curves of micro light emitting diode (uLED) and organic light emitting diode (OLED) are different, that is, the pulse amplitude modulation (PAM) circuit for driving the organic light emitting diode needs to be matched with the global light emitting signal to control the light emission of the micro light emitting diode. Therefore, in order to drive the micro light emitting diode, the existing driving circuit needs to be modified or redesigned accordingly. SUMMARY

[0004] The present application provides a display panel, by configuring a plurality of control circuits in the pixel array and at least one sub-pixel is controlled to emit light by the corresponding control circuit, thereby improving the control efficiency of the sub-pixel.

[0005] The display panel of the present application comprises a plurality of pixel groups. Each pixel group comprises a pulse width modulation control circuit and a plurality of sub-pixels. The pulse width modulation control circuit receives pulse width modulation data and a global light emitting signal to provide a local light emitting signal, wherein the pulse width of the local light emitting signal is less than or equal to the pulse width of the global light emitting signal. The plurality of sub-pixels each have a light emitting diode, wherein the sub-pixels comprise a first sub-pixel, the first sub-pixel receives first pulse amplitude modulation data and a local or global light emitting signal, wherein the first pulse amplitude modulation data determines a first drive current flowing through the light emitting diode of the first sub-pixel, and the local light emitting signal determines the passing time of the first drive current flowing through the light emitting diode of the first sub-pixel.

[0006] Based on the above, the display panel of the present application embodiment, through the pulse width modulation control circuit in the pixel group, at least one sub-pixel in the pixel group can adjust the light emitting time of the light emitting diode through the pulse width modulation control circuit, thereby improving the control efficiency of the sub-pixel displaying a specific gray scale range (such as low gray scale), and the power consumption of the display panel can be further reduced through the adjustment of the light emitting time.

[0007] In order to make the above features and advantages of the present application more obvious and easy to understand, the following embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 System diagram of a display panel according to an embodiment of the present application.

[0009] Figure 2 Circuit diagram of a pulse width modulation control circuit according to an embodiment of the present application.

[0010] Figure 3 Circuit diagram of a first sub-pixel according to an embodiment of the present application.

[0011] Figure 4 Circuit diagram of a second sub-pixel according to an embodiment of the present application.

[0012] Figure 5 Drive waveform timing chart of a display panel according to an embodiment of the present application.

[0013] Figure 6 Circuit diagram of a pulse width modulation control circuit according to another embodiment of the present application.

[0014] Figure 7 Circuit diagram of a first sub-pixel according to another embodiment of the present application.

[0015] REFERENCE NUMERALS

[0016] 100: display panel

[0017] C1: first capacitor

[0018] C2: second capacitor

[0019] C3: third capacitor

[0020] CTC, 200, 600: pulse width modulation control circuit

[0021] EM: global emission signal

[0022] GPX: group of pixels

[0023] Id1, Id2: drive current

[0024] OVDD: second high voltage

[0025] OVSS: third low voltage

[0026] PAM_Data1 - PAM_Data4: pulse amplitude modulation data

[0027] PEM: local emission signal

[0028] PWM_Data: pulse width modulation data

[0029] Rst_PEM: Reset signal

[0030] S1: First control signal

[0031] S2: Second control signal

[0032] SE1, SE2, EE1, EE2: Enabling period

[0033] SPX1~SPX4, 300, 400, 700: Subpixels

[0034] Sweep: Oscillation signal

[0035] T1: First transistor

[0036] T10: Tenth Transistor

[0037] T12: Twelfth Transistor

[0038] T13: Thirteenth Transistor

[0039] T14: Fourteenth Transistor

[0040] T2: Second transistor

[0041] T3: Third transistor

[0042] T4: Fourth transistor

[0043] T5: Fifth transistor

[0044] T6: Sixth transistor

[0045] T7: Seventh Transistor

[0046] T8: Eighth transistor

[0047] T9: Ninth Transistor

[0048] uD1: Miniature LED

[0049] VGH: First High Voltage

[0050] VGL: Second Low Voltage

[0051] Vn: First low voltage

[0052] Vp: Third highest voltage

[0053] T11: Eleventh transistor Detailed Implementation

[0054] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology and this invention, and will not be interpreted as having idealized or overly formal meanings unless expressly defined herein.

[0055] It should be understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, and / or parts should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or part from another. Therefore, the “first element,” “component,” “region,” “layer,” or “part” discussed below may be referred to as a second element, component, region, layer, or part without departing from the teachings of this document.

[0056] The terminology used herein is for the purpose of describing particular embodiments only and is not restrictive. As used herein, unless the content clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one.” “Or” means “and / or.” As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It should also be understood that, when used in this specification, the terms “comprising” and / or “comprising” specify the presence of the stated features, areas, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, areas, integrals, steps, operations, elements, components, and / or combinations thereof.

[0057] Figure 1 This is a system schematic diagram of a display panel according to an embodiment of the present invention. Please refer to... Figure 1 In this embodiment, the display panel 100 includes multiple pixel groups GPX, wherein each pixel group GPX includes a pulse width modulation control circuit CTC and multiple sub-pixels SPX1 to SPX4.

[0058] The pulse width modulation control circuit (CTC) receives pulse width modulation data PWM_Data and global light emission signal EM, and provides a local light emission signal PEM based on the pulse width modulation data PWM_Data and the global light emission signal EM, wherein the pulse width of the local light emission signal PEM is less than or equal to the pulse width of the global light emission signal EM.

[0059] Sub-pixels SPX1 to SPX4 each have a light-emitting diode (e.g. Figure 3 , Figure 4 and Figure 7The miniature light-emitting diode (LED) uD1 shown has some sub-pixels (such as sub-pixels SPX1 and SPX2) receiving local light-emitting signals PEM (corresponding to the first sub-pixel) from the pulse width modulation control circuit CTC. Furthermore, sub-pixels SPX1 and SPX2 individually receive pulse amplitude modulation data PAM_Data1 and PAM_Data2 (corresponding to the first pulse amplitude modulation data) and the local light-emitting signal PEM. The pulse amplitude modulation data PAM_Data1 and PAM_Data2 determine the first driving current (e.g., PAM_Data1 and PAM_Data2) flowing through the LEDs of sub-pixels SPX1 and SPX2. Figure 3 The driving current Id1 is shown, and the local light emission signal PEM determines the passage time of the first driving current through the light emission diodes of sub-pixels SPX1 and SPX2.

[0060] Furthermore, the remaining sub-pixels (such as sub-pixels SPX3 and SPX4) directly receive the global emission signal EM, that is, bypassing the pulse width modulation control circuit CTC. Sub-pixels SPX3 and SPX4 individually receive pulse amplitude modulation data PAM_Data3 and PAM_Data4 (corresponding to the second pulse amplitude modulation data) and the global emission signal EM. Among them, the pulse amplitude modulation data PAM_Data3 and PAM_Data4 determine the second driving current (e.g., EM) flowing through the light-emitting diodes of sub-pixels SPX3 and SPX4. Figure 4 The driving current Id2 is shown, and the global light emission signal EM determines the passage time of the second driving current through the light emission diodes of sub-pixels SPX3 and SPX4.

[0061] Based on the above, through the pulse width modulation control circuit in the pixel group, at least one sub-pixel in the pixel group can adjust the light emission time of the light-emitting diode via the pulse width modulation control circuit, thereby improving the control efficiency of the sub-pixel displaying a specific grayscale range (e.g., low grayscale), and further reducing the power consumption of the display panel by adjusting the light emission time.

[0062] In this embodiment of the invention, sub-pixels SPX1 to SPX4 may include at least one red sub-pixel, at least one green sub-pixel, and at least one blue sub-pixel, but this embodiment of the invention is not limited thereto. For example, a sub-pixel may include at least one red sub-pixel, at least one green sub-pixel, at least one blue sub-pixel, and at least one white sub-pixel.

[0063] In this embodiment of the invention, some sub-pixels SPX1 to SPX4 receive the local emission signal PEM from the pulse width modulation control circuit CTC, and some sub-pixels SPX1 to SPX4 directly receive the global emission signal EM. However, in other embodiments, at least one of the sub-pixels SPX1 to SPX4 of the pixel group GPX receives the local emission signal PEM, or all sub-pixels SPX1 to SPX4 of the pixel group GPX receive the local emission signal PEM. This depends on the circuit design, and this embodiment of the invention is not limited thereto.

[0064] Figure 2 This is a circuit diagram of a pulse width modulation control circuit according to an embodiment of the present invention. Please refer to... Figure 1 and 2 In this embodiment, the pulse width modulation control circuit CTC is exemplified by the pulse width modulation control circuit 200. The pulse width modulation control circuit 200 includes, for example, a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, a fifth transistor T5, a sixth transistor T6, a seventh transistor T7, a first capacitor C1, and a second capacitor C2. The first transistor T1, the second transistor T2, the third transistor T3, the fourth transistor T4, the fifth transistor T5, the sixth transistor T6, and the seventh transistor T7 are exemplified by P-type transistors, but this embodiment of the invention is not limited thereto.

[0065] The first transistor T1 has a first terminal, a control terminal for receiving a first control signal S1, and a second terminal for receiving a first low voltage Vn. A first capacitor C1 is coupled between the oscillation signal Sweep and the first terminal of the first transistor T1. The second transistor T2 has a first terminal coupled to the first terminal of the first transistor T1, a control terminal for receiving a second control signal S2, and a second terminal. The third transistor T3 has a first terminal coupled to the second terminal of the second transistor T2, a control terminal for receiving a global light emission signal EM, and a second terminal for providing a local light emission signal PEM.

[0066] The fourth transistor T4 has a first terminal coupled to the second terminal of the third transistor T3, a control terminal for receiving the reset signal Rst_PEM, and a second terminal for receiving the second low voltage VGL, wherein the second low voltage VGL may be different from the first low voltage Vn. The second capacitor C2 is coupled between the second terminal of the third transistor T3 and the second low voltage VGL. The fifth transistor T5 has a first terminal, a control terminal coupled to the first terminal of the first transistor T1, and a second terminal coupled to the second terminal of the second transistor T2.

[0067] The sixth transistor T6 has a first terminal for receiving pulse width modulation data PWM_Data, a control terminal for receiving the second control signal S2, and a second terminal coupled to the first terminal of the fifth transistor T5. The seventh transistor T7 has a first terminal for receiving the first high voltage VGH, a control terminal for receiving the global emission signal EM, and a second terminal coupled to the first terminal of the fifth transistor T5.

[0068] Figure 3 This is a circuit diagram of a first sub-pixel according to an embodiment of the present invention. Please refer to... Figure 1 and Figure 3 In this embodiment, the sub-pixels SPX1 and SPX2 that receive the local light emission signal PEM from the pulse width modulation control circuit CTC are, for example, sub-pixel 300. Sub-pixel 300 includes, for example, a micro light-emitting diode uD1, an eighth transistor T8, a ninth transistor T9, a tenth transistor T10, an eleventh transistor T11, a twelfth transistor T12, a thirteenth transistor T13, a fourteenth transistor T14, and a third capacitor C3. The eighth transistor T8, the ninth transistor T9, the tenth transistor T10, the eleventh transistor T11, the twelfth transistor T12, the thirteenth transistor T13, and the fourteenth transistor T14 are, for example, P-type transistors, but this embodiment of the invention is not limited thereto.

[0069] The light-emitting diode uD1 has an anode and a cathode that receives a third low voltage OVSS, wherein the third low voltage OVSS may be different from the first low voltage Vn and the second low voltage VGL. The eighth transistor T8 has a first terminal, a control terminal that receives the local light-emitting signal PEM, and a second terminal coupled to the anode of the light-emitting diode uD1. The ninth transistor T9 has a first terminal that receives a second high voltage OVDD, a control terminal, and a second terminal coupled to the first terminal of the eighth transistor T8, wherein the second high voltage OVDD may be different from the first high voltage VGH.

[0070] The tenth transistor T10 has a first terminal, a control terminal that receives the second control signal S2, and a second terminal that is coupled to the first terminal of the eighth transistor T8. The eleventh transistor T11 has a first terminal that is coupled to the first terminal of the tenth transistor T10, a control terminal that receives the first control signal S1, and a second terminal that receives the first low voltage Vn. The twelfth transistor T12 has a first terminal that is coupled to the control terminal of the ninth transistor T9, a control terminal that receives the second control signal S2, and a second terminal that is coupled to the first terminal of the tenth transistor T10.

[0071] The thirteenth transistor T13 has a first terminal for receiving a third high voltage Vp, a control terminal, and a second terminal, wherein the third high voltage Vp may be different from the first high voltage VGH and the second high voltage OVDD. A third capacitor C3 is coupled between the second terminal of the thirteenth transistor T13 and the control terminal of the ninth transistor T9. The fourteenth transistor T14 has a first terminal for receiving the corresponding pulse amplitude modulation data PAM_Data (i.e., one of pulse amplitude modulation data PAM_Data1 and PAM_Data2), a control terminal, and a second terminal.

[0072] Figure 4 This is a circuit diagram of a second sub-pixel according to an embodiment of the present invention. Please refer to... Figure 1 , Figure 3 and Figure 4 In this embodiment, the sub-pixels SPX3 and SPX3 directly receive the global emission signal EM. For example, sub-pixel 400 is used as an example. The difference between sub-pixel 400 and sub-pixel 300 lies in the eighth transistor T8 and the thirteenth transistor T13. In this embodiment, the control terminals of both the eighth transistor T8 and the thirteenth transistor T13 receive the global emission signal EM, and the corresponding pulse amplitude modulation data PAM_Data received by the fourteenth transistor T14 will be one of the pulse amplitude modulation data PAM_Data3 and PAM_Data4.

[0073] Figure 5 This is a timing diagram of the driving waveform of a display panel according to an embodiment of the present invention. Please refer to... Figures 2 to 5 In the pulse width modulation control circuit 200, during the period SE1 when the first control signal S1 is enabled, the first transistor T1 is turned on, and a first low voltage Vn is transmitted to one end of the first capacitor C1 and the control terminal of the fifth transistor T5, at which time the fifth transistor T5 is turned on. Then, during the period SE2 when the second control signal S2 is enabled, the second transistor T2 and the sixth transistor are turned on, and pulse width modulation data PWM_Data is transmitted to one end of the first capacitor C1. At this time, the voltage difference of the first capacitor C1 is determined by the oscillation signal Sweep, the pulse width modulation data PWM_Data, and the critical voltage of the second transistor T2.

[0074] During the period EE2 when the reset signal Rst_PEM is enabled, the fourth transistor turns on to pull the local light-emitting signal PEM to a low voltage level (i.e., it is enabled). During the period EE1 when the global light-emitting signal EM is enabled, the third transistor T3 and the seventh transistor T7 turn on, and the voltage level of the oscillation signal Sweep gradually decreases over time. Then, when the voltage at the control terminal of the fifth transistor T5 reaches the turn-on threshold voltage, the fifth transistor T5 turns on, so that the first high voltage VGH is transmitted to the second terminal of the third transistor to raise the voltage level of the local light-emitting signal PEM. During the period EE1 when the global light-emitting signal EM is enabled, the pulse width of the local light-emitting signal PEM is at most equal to the pulse width of the global light-emitting signal EM, which is determined by the voltage level of the pulse width modulation data PWM_Data.

[0075] On the other hand, please refer to Figure 3 , Figure 4 and Figure 5 In sub-pixels 300 or 400, during the period SE1 when the first control signal S1 is enabled, the eleventh transistor T11 is turned on to transfer the first low voltage Vn between the tenth transistor T10 and the twelfth transistor T12. During the period SE2 when the second control signal S2 is enabled, the tenth transistor T10, the twelfth transistor T12, and the fourteenth transistor T14 are turned on, and the voltage across the third capacitor C3 is related to the second high voltage OVDD, the threshold voltage of the ninth transistor T9, and the pulse amplitude modulation data PAM_Data.

[0076] During the period when the global light-emitting signal EM is enabled (or during the period when the local light-emitting signal PEM is enabled), the eighth transistor T8 and the thirteenth transistor T13 will be turned on. Since the voltage across the third capacitor C3 is related to the pulse amplitude modulation data PAM_Data, the drive current Id1 or Id2 flowing through the micro LED uD1 will be related to the received pulse amplitude modulation data PAM_Data.

[0077] Figure 6 This is a circuit diagram of a pulse width modulation control circuit according to another embodiment of the present invention. Please refer to... Figure 2 and Figure 6The pulse width modulation control circuit 600 is largely the same as the pulse width modulation control circuit 200, except that the second terminal of the fourth transistor T4 receives a first low voltage Vn, and the first terminal of the seventh transistor T7 receives a second high voltage OVDD, wherein the same or similar components are referred to by the same or similar designations. In other words, in this embodiment, the voltage level of the second terminal of the fourth transistor T4 can be the same as the voltage level of the second terminal of the first transistor T1, and the voltage level of the first terminal of the seventh transistor T7 can be the same as the voltage level of the first terminal of the ninth transistor of the sub-pixel (such as sub-pixel 300 or 400).

[0078] Figure 7 This is a circuit diagram of a first sub-pixel according to another embodiment of the present invention. Please refer to... Figure 3 and Figure 7 Sub-pixel 700 is largely the same as sub-pixel 300, except that the control terminal of the thirteenth transistor T13 receives the global emission signal EM, where the same or similar components use the same or similar labels. Since the pulse width of the global emission signal EM is greater than or equal to the pulse width of the local emission signal PEM, replacing the local emission signal PEM with the global emission signal EM does not affect the operation of sub-pixel 700.

[0079] Based on the above, as shown in sub-pixels 300 and 700, in sub-pixels SPX1 and SPX2 that receive the local emission signal PEM, the control terminal of the thirteenth transistor T13 can receive either the local emission signal PEM or the global emission signal EM. Furthermore, as shown in sub-pixel 400, in sub-pixels SPX3 and SPX3 that directly receive the global emission signal EM, the control terminal of the thirteenth transistor T13 only receives the global emission signal EM.

[0080] In summary, the display panel of the present invention, through the pulse width modulation control circuit in the pixel group, allows at least one sub-pixel in the pixel group to adjust the light emission time of the light-emitting diode via the pulse width modulation control circuit, thereby improving the control efficiency of the sub-pixel displaying a specific grayscale range (e.g., low grayscale), and further reducing the power consumption of the display panel by adjusting the light emission time.

[0081] Although the present invention has been disclosed above with reference to 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 concept and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A display panel, comprising: Multiple pixel groups, each of which includes: A pulse width modulation control circuit receives pulse width modulation data and a global light emission signal to provide a local light emission signal, wherein the pulse width of the local light emission signal is less than or equal to the pulse width of the global light emission signal. The system comprises multiple sub-pixels, each having a light-emitting diode (LED). These sub-pixels include a first sub-pixel. The first sub-pixel receives a first pulse amplitude modulation (PWM) data and a local light-emitting signal. The first PWM data determines a first driving current flowing through the LED of the first sub-pixel, and the local light-emitting signal determines the passage time of the first driving current through the LED of the first sub-pixel. The pulse width modulation control circuit includes: A first transistor has a first terminal, a control terminal that receives a first control signal, and a second terminal that receives a first low voltage; A first capacitor is coupled between a oscillating signal and the first terminal of the first transistor; A second transistor has a first terminal coupled to the first terminal of the first transistor, a control terminal for receiving a second control signal, and a second terminal; A third transistor has a first terminal coupled to the second terminal of the second transistor, a control terminal for receiving the global light emission signal, and a second terminal for providing the local light emission signal; A fourth transistor has a first terminal coupled to the second terminal of the third transistor, a control terminal receiving a reset signal, and a second terminal receiving a second low voltage; A second capacitor is coupled between the second terminal of the third transistor and the second low voltage. A fifth transistor has a first terminal, a control terminal coupled to the first terminal of the first transistor, and a second terminal coupled to the second terminal of the second transistor; A sixth transistor has a first terminal for receiving the pulse width modulation data, a control terminal for receiving the second control signal, and a second terminal coupled to the first terminal of the fifth transistor; and A seventh transistor has a first terminal for receiving a first high voltage, a control terminal for receiving the global light emission signal, and a second terminal coupled to the first terminal of the fifth transistor.

2. The display panel of claim 1, wherein the sub-pixels further include a second sub-pixel, the second sub-pixel receiving a second pulse amplitude modulation data and the global light emission signal, wherein the second pulse amplitude modulation data determines a second driving current flowing through the light emission diode of the second sub-pixel, and the global light emission signal determines the passage time of the second driving current through the light emission diode of the second sub-pixel.

3. The display panel of claim 2, wherein each of the sub-pixels comprises: The light-emitting diode has an anode and a cathode that receives a third low voltage; An eighth transistor has a first terminal, a control terminal for receiving one of the local light emission signal and the global light emission signal, and a second terminal coupled to the anode of the light emission diode; A ninth transistor has a first terminal for receiving a second high voltage, a control terminal, and a second terminal coupled to the first terminal of the eighth transistor; A tenth transistor has a first terminal, a control terminal for receiving the second control signal, and a second terminal coupled to the first terminal of the eighth transistor; An eleventh transistor has a first terminal coupled to the first terminal of the tenth transistor, a control terminal for receiving the first control signal, and a second terminal for receiving the first low voltage; A twelfth transistor has a first terminal coupled to the control terminal of the ninth transistor, a control terminal for receiving the second control signal, and a second terminal coupled to the first terminal of the tenth transistor; A thirteenth transistor has a first terminal for receiving a third high voltage, a control terminal, and a second terminal; A third capacitor is coupled between the second terminal of the thirteenth transistor and the control terminal of the ninth transistor; and A fourteenth transistor has a first terminal for receiving one of the first pulse amplitude modulation data and the second pulse amplitude modulation data, a control terminal, and a second terminal. In the first sub-pixel, the control terminal of the thirteenth transistor receives one of the local light emission signal and the global light emission signal, and in the second sub-pixel, the control terminal of the thirteenth transistor receives the global light emission signal.

4. The display panel of claim 3, wherein the second low voltage is the same as the first low voltage.

5. The display panel of claim 3, wherein the first high voltage is the same as the second high voltage.

6. The display panel of claim 1, wherein the sub-pixels include at least one red sub-pixel, at least one green sub-pixel, and at least one blue sub-pixel.

7. The display panel as claimed in claim 1, wherein the light-emitting diode includes a miniature light-emitting diode.

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