Pixel circuit, pixel array, display panel, and display apparatus

Abstract

The present application relates to the technical field of display, and provides a pixel circuit, a pixel array, a display panel, and a display apparatus. The pixel circuit comprises: a digital logic module, configured to generate a pulse width modulation signal; a switch module, connected to the digital logic module; and a driving transistor, connected to the switch module. The digital logic module can control the switch module by means of the pulse width modulation signal, so as to control the on-off of the driving transistor, thereby controlling the brightness of a light-emitting device. The technical solution in the present application can reduce the voltage drop loss of the pixel circuit and reduce the area occupied by the pixel circuit.

Description

Pixel circuits, pixel arrays, display panels, and display devices

[0001] This application claims priority to Chinese Patent Application No. 202411480422.3, filed on October 22, 2024, entitled "Pixel Circuit, Pixel Array, Display Panel and Display Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of display technology, and more particularly to pixel circuits, pixel arrays, display panels, and display devices. Background Technology

[0003] Currently, in micro uLED display technology, the pixel circuits in the display area use a mixed-signal driving mode to control the current required by the light-emitting device and its on / off state. The main driving method is to use analog circuits to modulate the current range and digital logic circuits to control the current on / off state.

[0004] Typically, in pixel circuits, the driving transistor controls the magnitude of the analog current, while other switching transistors control the on / off state of the current in the light-emitting branch. With this structure, the pixel circuit suffers from two main problems: firstly, voltage losses due to the multiple transistors (driving and switching transistors); and secondly, an excessively large area occupied by the pixel circuit due to the large number of transistors. Summary of the Invention

[0005] This application provides a pixel circuit, a pixel array, a display panel, and a display device, which are used to provide a technical solution for reducing the voltage drop across the pixel circuit and reducing the area occupied by the pixel circuit.

[0006] In a first aspect, this application provides a pixel circuit, including: a digital logic module for generating pulse width modulation signals.

[0007] The switch module connects to the digital logic module.

[0008] The driver transistor is connected to the switching module.

[0009] The digital logic module can control the switching module through pulse width modulation signals to control the on / off state of the driving transistor, thereby controlling the brightness of the light-emitting device.

[0010] In one alternative implementation, the pixel circuit further includes a reference transistor connected to the driving transistor via a switching module to form a current mirror circuit with the driving transistor.

[0011] The reference transistor is used to provide a reference current to the driver transistor when the switching module is turned on. The reference current of the driver transistor is replicated based on the current mirror principle to drive the light-emitting device.

[0012] In one alternative implementation, the driving transistor is a PMOS transistor, and the magnitude of the reference current can be determined based on the width-to-length ratio of the reference transistor and the driving transistor.

[0013] In one alternative implementation, the switching module includes a first switching unit connected to the gate of the digital logic module and the driving transistor.

[0014] The first switching unit is used to turn on under the control of the pulse width modulation signal and to provide the reference current output by the reference tube to the driving tube.

[0015] In one alternative implementation, the first switching unit includes a first switching transistor and a second switching transistor.

[0016] The gate of the first switching transistor is connected to the digital logic module, its input is connected to the reference transistor, and its output is connected to the gate of the driving transistor. It is used to turn on under the control of the pulse width modulation signal so as to provide the reference current output by the reference transistor to the driving transistor.

[0017] The gate of the second switch is connected to the digital logic module, the input is connected to the first reset voltage terminal, and the output is connected to the gate of the driver transistor. It is used to turn on the first switch when the pulse width modulation signal turns off the first switch and to provide the first reset voltage provided by the first reset voltage terminal to the driver transistor; wherein, the first reset voltage is used to turn off the driver transistor.

[0018] In one alternative implementation, the first switching unit includes a first transmission gate, a second transmission gate, and an inverter.

[0019] The input of the inverter is connected to the digital logic module, and the output is connected to the first transmission gate and the second transmission gate. The digital logic module is also connected to the first transmission gate and the second transmission gate.

[0020] The first transmission gate is also connected to the gates of the reference transistor and the drive transistor, and is used to close under the control of the pulse width modulation signal to provide the reference current output by the reference transistor to the drive transistor.

[0021] The second transmission gate is also connected to the first reset voltage terminal and the gate of the driving transistor, and is used to close when the pulse width modulation signal turns off the first transmission gate, and to provide the first reset voltage provided by the first reset voltage terminal to the driving transistor; wherein, the first reset voltage is used to turn off the driving transistor.

[0022] In one optional embodiment, the switching module further includes a second switching unit, which is connected to the digital logic module, the light-emitting device, and the second reset voltage terminal. The second switching unit is used to provide the second reset voltage output from the second reset voltage terminal to the light-emitting device when the pulse width modulation signal controls the driving transistor to turn off, wherein the second reset voltage is used to turn off the light-emitting device.

[0023] In one optional embodiment, the second switching unit includes a third switching transistor; the gate of the third switching transistor is connected to the digital logic module, the input terminal is connected to the second reset voltage terminal, and the output terminal is connected to the light-emitting device, and is used to turn on under the control of the pulse width modulation signal when the driving transistor is turned off by the pulse width modulation signal, so as to provide the second reset voltage output from the second reset voltage terminal to the light-emitting device.

[0024] In one alternative implementation, a voltage regulator module is also included, which is connected between the reference transistor and the switching module to provide a stable voltage between the reference transistor and the switching module.

[0025] In one alternative embodiment, the voltage regulator module includes a capacitor, one end of which is connected to a voltage signal terminal and the other end of which is connected between a reference transistor and a switching module, for providing a stable voltage generated at the voltage signal terminal to the space between the reference transistor and the switching module.

[0026] In a second aspect, this application also provides a pixel array, comprising: m rows and n columns of pixel units, and a reference tube connected to each row of pixel units or each column of pixel units; wherein each pixel unit includes the pixel circuit of any one of the first aspects.

[0027] The reference transistor is connected to the switching module of the pixel unit in the corresponding row or column, and is used to provide a reference current to the corresponding driving transistor through the corresponding switching module.

[0028] In one alternative implementation, the digital logic module is used to control the turn-on time of the light-emitting device driven by the corresponding pixel unit to be different from the turn-on time of the light-emitting devices driven by at least some of the other pixel units.

[0029] Thirdly, this application also provides a display panel including the pixel array of any of the second aspects.

[0030] Fourthly, this application also provides a display device, including the display panel of the third aspect.

[0031] The technical solution provided in this application utilizes a pulse width modulation signal generated by a digital logic module to control the conduction of a switching module, thereby controlling the on / off state of a driving transistor and thus controlling the brightness of the light-emitting device. It should be understood that the brightness of the light-emitting device is related to the current flowing through it and the duration of its emission. In this application, the current flowing through the light-emitting device is controlled by the output current of the driving transistor, and the duration of its emission is controlled by the on / off state of the driving transistor. Therefore, the brightness of the light-emitting device is determined by the driving transistor. Based on this, this application can control the brightness of the light-emitting device using only the driving transistor without needing to use other transistors. Therefore, the pixel circuit in this application not only reduces the voltage drop caused by the use of other transistors in the prior art but also saves the area occupied by other transistors in the prior art, thereby reducing the area occupied by the pixel circuit.

[0032] Furthermore, the digital logic module in this application can directly control the on / off state of the drive transistor through the switching module, without needing to connect other devices in the prior art. Therefore, the area occupied by the pixel circuit can be further reduced. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0034] Figure 1 is a schematic diagram of a pixel circuit provided in an embodiment of this application;

[0035] Figure 2 is a schematic diagram of a switch module provided in an embodiment of this application;

[0036] Figure 3 is a schematic diagram of another switching module provided in an embodiment of this application;

[0037] Figure 4 is a schematic diagram of a pixel array provided in an embodiment of this application;

[0038] Figure 5 is a pulse width control timing diagram of a pixel array provided in an embodiment of this application;

[0039] Figure 6 is a schematic diagram of the equivalent circuit between the gate of the driving transistor of a pixel unit and the pulse width control signal according to an embodiment of this application.

[0040] Figure 7 is a timing diagram of the global activation of the pulse width control signal in a pixel array according to an embodiment of this application;

[0041] Figure 8 is a schematic diagram illustrating the effect of the pulse width control signal on the luminous current of the light-emitting device when the pulse width control signal is globally turned on in the pixel array, according to an embodiment of this application.

[0042] Figure 9 is a timing diagram of the global shutdown of the pulse width control signal in a pixel array provided in an embodiment of this application;

[0043] Figure 10 is a schematic diagram showing the effect of the light-emitting current of the light-emitting device when the pulse width control signal in the pixel array is globally turned off, according to an embodiment of this application.

[0044] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0045] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. It is understood that the terms “first,” “second,” etc., as used herein may be used to describe various information or data, but these elements are not limited by these terms. These terms are only used to distinguish first information from another type of information. For example, without departing from the scope of this application, first action information may be referred to as second action information, and similarly, second action information may be referred to as first action information. Both first action information and second action information are action information, but they are not the same action information.

[0047] Currently, in micro uLED display technology, the pixel circuits in the display area use a mixed-signal driving mode to control the current required by the light-emitting device and its on / off state. The main driving method is to use analog circuits to modulate the current range and digital logic circuits to control the current on / off state.

[0048] Typically, in pixel circuits, the driving transistor controls the magnitude of the analog current, while other switching transistors control the on / off state of the current in the light-emitting branch. With this structure, the pixel circuit suffers from two main problems: firstly, voltage losses due to the multiple transistors (driving and switching transistors); and secondly, an excessively large area occupied by the pixel circuit due to the large number of transistors.

[0049] To address the aforementioned issues, this application proposes the following technical concept: designing a technical solution that can apply both the pulse width modulation signal and the current magnitude for controlling the light-emitting device to a single transistor. This technical solution can reduce the number of transistors, thereby reducing voltage drop and the area occupied by the pixel circuit.

[0050] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0051] Referring to FIG1, an embodiment of this application provides a pixel circuit, which includes: a digital logic module, a switching module, and a driving transistor T1.

[0052] The digital logic module generates a pulse width modulation (PWM) signal and outputs it to the switching module. The switching module is then turned on or off under the control of this PWM signal.

[0053] The switching module is also connected to the driver transistor. When the switching module is turned on, the digital logic module can control the switching on and off of the driver transistor via a pulse width modulation signal, thereby controlling the brightness of the light-emitting device. The brightness of the light-emitting device is related to the current flowing through it and the duration of its light emission. To further explain, the brightness of the light-emitting device can be obtained by integrating the current flowing through it over the duration of its light emission.

[0054] The aforementioned digital logic module is used to generate a pulse width modulation signal based on the brightness grayscale of the light-emitting device. This digital logic module can employ any suitable structure; this application does not impose any special limitations. For example, it can use basic logic gates, combinational logic circuits, or sequential logic circuits.

[0055] The aforementioned switching module is used to control the on / off switching of digital logic units between driving transistors. The switching module may be composed of switching devices, such as at least one of transistors, relays, MOSFETs, IGBTs, and logic gates, and the embodiments of this application do not impose any special limitations.

[0056] The digital logic module provides pulse width modulation signals to the switching module and the driving transistor, changing its on / off state, thereby controlling the on / off state of the driving transistor and thus controlling the current flow between the input and output terminals of the driving transistor to drive the light-emitting device.

[0057] The aforementioned driving transistor can be a bipolar junction transistor (BJT), a field-effect transistor (FET), a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated-gate bipolar transistor (IGBT), or a P-channel MOSFET. This application does not impose specific limitations on this.

[0058] The aforementioned light-emitting device can be any electronic component capable of converting electrical energy into light energy, and the embodiments of this application do not impose any special limitations. For example, the light-emitting device can be a light-emitting diode (LED), an organic light-emitting diode (OLED), a micro LED, or a laser diode (LD), etc.

[0059] It should be understood that the brightness of a light-emitting device is related to the current flowing through it and the duration of its emission. In this embodiment, the current flowing through the light-emitting device is controlled by the output current of the driving transistor, and the duration of its emission is controlled by the switching on and off of the driving transistor. Therefore, the brightness of the light-emitting device is determined by the driving transistor. Thus, this application can control the brightness of the light-emitting device using only the driving transistor without the need for other transistors. Therefore, the pixel circuit in this application not only reduces voltage drop caused by the use of other transistors in the prior art, but also saves the area occupied by other transistors in the prior art, thereby reducing the area occupied by the pixel circuit.

[0060] Furthermore, the digital logic module in this embodiment can directly control the on / off state of the drive transistor through the switching module, without needing to connect other devices in the prior art. Therefore, the area occupied by the pixel circuit can be further reduced.

[0061] It should be further understood that the pixel circuit in the embodiments of this application reduces the number of transistors. With the same digital logic module, this application can be applied to smaller pixel pitch and larger pixel density, thereby improving display quality and display clarity.

[0062] In an optional embodiment, referring to FIG1, the pixel circuit provided in this application embodiment may further include a reference transistor T2, which is connected to the driving transistor T1 through the switching module 10 to form a current mirror circuit with the driving transistor T1.

[0063] The reference transistor T2 is used to provide a reference current to the drive transistor T1 when the switching module 10 is turned on. The drive transistor T1 replicates the reference current based on the current mirror principle to drive the light-emitting device to emit light.

[0064] In a specific example, referring to Figure 1, reference transistor T2 is connected to driver transistor T1 via switch module 10. The input terminal of driver transistor T1 is connected to the voltage signal terminal ELVDD (Electroluminescent Voltage Drain Drive), and its output terminal is connected to the first terminal of light-emitting device LL. The second terminal of light-emitting device LL is connected to the ELVSS terminal (common ground voltage terminal). When the pulse width modulation signal provided by the digital logic module controls the switch module 10 to turn on, the driver transistor replicates the reference current Iref provided by reference transistor T2. This reference current Iref is used to drive light-emitting device LL to emit light. The brightness of light-emitting device LL is related to this reference current. Based on this, the brightness of light-emitting device LL can be controlled by driver transistor T1.

[0065] In this embodiment, the reference transistor T2 may be located outside the pixel unit, while the digital logic module, switch module, driver transistor, and light-emitting device LL are located inside the pixel unit. That is, in the display area of ​​the display panel, each pixel unit may include a digital logic module, switch module 10, driver transistor T1, and light-emitting device LL, with the reference transistor T2 disposed outside the pixel unit.

[0066] Optionally, referring to Figure 1, the first terminal of the reference transistor T2 is connected to the voltage signal terminal ELVDD, the second terminal is connected to the reference current source, and the third terminal is connected to the gate of the driving transistor T1 through a switching module. The voltage signal terminal ELVDD can be a voltage source for driving the light-emitting device. Referring to Figure 1, the switching transistor T2 and the driving transistor T1 form a current mirror structure, used to copy the reference current Iref from the reference current source to the output terminal of the driving transistor T2.

[0067] Optionally, the driving transistor is a PMOS transistor, and the magnitude of the reference current can be determined based on the width-to-length ratio of the reference transistor and the driving transistor.

[0068] Both the reference transistor T2 and the driver transistor T1 mentioned above can be PMOS transistors. In this case, the reference transistor T2 and the driver transistor T1 form a PMOS current mirror. The output current I of the driver transistor T1 is... T1 =K*Iref, that is, the current through the light-emitting device is K*Iref. Where K is the width-to-length ratio of T2 and T1, that is, the current of the light-emitting device LL is determined by the reference current Iref and the width-to-length ratio of T2 and T1. Therefore, the current of the light-emitting device in this embodiment can be modulated, thereby realizing precise control of the light-emitting current of the light-emitting device.

[0069] Based on the above description, the current value of the light-emitting device in this embodiment is determined by the Iref current, so there will be no leakage current phenomenon of the light-emitting device. Furthermore, when the Iref current remains unchanged, the output current of the driving transistor T1 will not decrease during the light-emitting time, so the brightness of the light-emitting device will not decrease.

[0070] Based on the above description, the embodiments of this application can achieve precise current replication through a current mirror structure, enabling accurate control of the brightness of each pixel, thereby improving display quality. This can be applied to fields such as OLED displays and MicroLED displays.

[0071] The overall structure and function of the pixel circuit in the embodiments of this application have been described above. The following descriptions will be made separately for each module.

[0072] Optionally, referring to FIG1, the switch module 10 may include a first switch unit 101 and a second switch unit 102.

[0073] The first switching unit 101 is connected to the gate of the digital logic module and the driving transistor T1, and is used to turn on under the control of the pulse width modulation signal and provide the reference current output by the reference transistor T2 to the driving transistor T2.

[0074] Specifically, referring to Figure 1, the first switching unit is connected to the gate of the digital logic module, the reference transistor T2, and the driving transistor T1. When the first switching unit is turned on, it transmits the pulse width modulation signal output by the digital logic module to the gate of the driving transistor T1 to control the on and off of the driving transistor T1. The first switching unit is also used to provide the reference current provided by the reference transistor T2 to the driving transistor T1 when the first switching unit is turned on.

[0075] The first switching unit 101 is also connected to the first reset voltage terminal Vg_rst, and is used to provide a first reset signal to the driving transistor when the pulse width modulation signal controls the first switching unit to turn off. The first reset signal is used to quickly turn off the driving transistor T2, so as to avoid the driving transistor not being completely turned off due to the previous reference current when the first switching unit is turned off, thereby affecting the brightness of the light-emitting device.

[0076] Based on the above description, the first switching unit in this embodiment has two functions: function one is to control the conduction of the driving transistor according to the pulse width modulation signal, and function two is to immediately turn off the driving transistor when the first switching unit is turned off according to the pulse width modulation signal and the first reset voltage.

[0077] Based on this, the embodiments of this application can divide the first switch unit into two parts according to its function, and these two parts perform different functions to improve the control accuracy of the switch module.

[0078] It should be understood that the two parts of the first switching unit described above can adopt any possible structure, and the embodiments of this application do not impose any special limitations on this.

[0079] For example, referring to Figure 2, the first switching unit includes a first switching transistor T4 and a second switching transistor T5; the input of the first switching transistor T4 is connected to the reference transistor, the gate is connected to the digital logic module, and the output is connected to the gate of the driving transistor; the input of the second switching transistor T5 is connected to the first reset voltage supply terminal Vg_rst, the gate is connected to the digital logic module, and the output is connected to the gate of the driving transistor.

[0080] The first switch T4 and the second switch T5 can be any suitable switch, and this embodiment does not impose any special limitations on them. Exemplary first switch T4 and second switch T5 can be one of the following switch types: bipolar junction transistor (BJT), metal-oxide-semiconductor field-effect transistor (MOSFET), insulated-gate bipolar transistor (IGBT), and field-effect transistor (JFET).

[0081] Based on the above structure, the first switch T4 is turned on under the control of the pulse width modulation signal. The reference current output by the reference tube is provided to the driving tube through the first switch T4. The driving tube replicates the reference current and outputs it. When the pulse width modulation signal output by the digital logic module turns off the first switch T4, the pulse width modulation signal controls the second switch T5 to turn on. The first reset voltage providing terminal Vg_rst provides a first reset signal to the second switch T5. The first reset signal is provided to the gate of the driving tube through the second switch T5 to immediately turn off the driving tube and avoid affecting the brightness of the light-emitting device.

[0082] For example, referring to Figure 3, the first switching unit includes a first transmission gate and a second transmission gate, and the switching module also includes an inverter FF. The first terminal of the inverter FF is connected to the digital logic module, the second terminal is connected to the first terminal of the first transmission gate and the first terminal of the second transmission gate, the second terminal of the first transmission gate is connected to the digital logic module, the third terminal is used to connect to the reference transistor, and the fourth terminal is connected to the gate of the driving transistor. The second terminal of the second transmission gate is connected to the digital logic module, the third terminal is used to connect to the first reset voltage supply terminal Vg_rst, and the fourth terminal is connected to the gate of the driving transistor.

[0083] Based on the above structure, according to the pulse width modulation signal provided by the digital logic module, the inverter FF outputs a first signal, turning on the first transmission gate and turning off the second transmission gate. At this time, the reference current provided by the reference transistor flows to the gate of the driving transistor through the first transmission gate. When it is necessary to turn off the driving transistor, according to the pulse width modulation signal provided by the digital logic module, the inverter FF outputs a second signal, turning off the first transmission gate and turning on the second transmission gate. At this time, the first reset voltage providing terminal Vg_rst provides the first reset voltage to the gate of the driving transistor, turning off the driving transistor.

[0084] The above content describes the structure and function of the first switching unit in detail. The following content describes the second switching unit.

[0085] Referring to Figure 1, the second switching unit 102 is connected to the digital logic module, the light-emitting device, and the second reset voltage terminal. It is used to provide the second reset voltage output from the second reset voltage terminal to the light-emitting device when the pulse width modulation signal controls the drive transistor to turn off. The second reset voltage is used to turn off the light-emitting device.

[0086] In this embodiment, since the second switching unit 102 is used to quickly turn off the light-emitting device when the driving transistor is turned off, the contrast of the display panel can be improved.

[0087] The second switching unit 102 can be any element or device capable of achieving the above functions. This application embodiment does not impose any special limitations. For example, referring to FIG1, the second switching unit 102 includes three switching transistors T3. The three switching transistors T3 can be bipolar transistors (BJT), field-effect transistors (FET), metal-oxide-semiconductor field-effect transistors (MOSFET), insulated-gate bipolar transistors (IGBT), or P-channel MOSFETs.

[0088] Specifically, the gate of the third switch T3 is connected to the digital logic module, the input is connected to the second reset voltage terminal, and the output is connected to the light-emitting device. It is used to turn on under the control of the pulse width modulation signal when the drive transistor is turned off, and at the same time provide the second reset voltage output from the second reset voltage terminal to the light-emitting device to quickly turn off the light-emitting device.

[0089] It is worth noting that the turn-off time of the light-emitting device and the turn-off time of the driving transistor can be understood as the same moment. That is to say, the light-emitting device and the driving transistor are turned off at the same time. Based on this, the contrast of the display panel is improved, thereby improving the display function of the display device.

[0090] In some embodiments, referring to FIG1, the pixel circuit provided in this application may further include a voltage regulator module connected between the reference transistor and the switching module for providing a stable voltage between the reference transistor and the switching module.

[0091] In this embodiment, the reference transistor is connected to the pixel circuit in a row of pixel units or a column of pixel units in the pixel array. This structure makes the potential of the node between the reference transistor and the switching module a common potential. At the same time, based on the sensitivity of the gate potential of the driving transistor, this embodiment provides a voltage regulator module at the node between the reference transistor and the switching module. The voltage regulator module is used to improve the influence of other trace coupling on the gate voltage of the driving transistor after the node voltage between the reference transistor and the switching module passes through a series of RC loadings.

[0092] The voltage regulator module can be any component or device that can achieve the above-mentioned voltage regulation function. This application does not impose any special limitations. For example, referring to FIG1, the voltage regulator module uses a capacitor.

[0093] Specifically, referring to Figure 1, one end of the capacitor is connected to the voltage signal terminal ELVDD, and the other end is connected between the reference transistor and the switching module, which is used to provide the stable voltage generated by the voltage signal terminal to the reference transistor and the switching module.

[0094] It should be understood that, based on the principle of capacitance, the voltage on both sides of a capacitor is the same. Therefore, a capacitor can provide a stable voltage generated at the voltage signal terminal to the reference transistor and the switching module.

[0095] Secondly, referring to FIG4, an embodiment of this application also provides a pixel array, including: m rows and n columns of pixel units, and a reference tube connected to each row of pixel units or each column of pixel units; wherein, each pixel unit includes the pixel circuit described in any one of the first aspects; the reference tube is connected to a switching module of the pixel unit in the corresponding row or column, and is used to provide a reference current to the corresponding driving tube T1 through the corresponding switching module.

[0096] Based on the description in the first aspect, the pixel array can use a pulse width modulation signal generated by a digital logic module to control the on-time of the switching module, wherein the pulse width modulation signal is generated based on the brightness grayscale of the light-emitting device. During the on-time of the switching module, a reference transistor provides a reference current to a driving transistor, which generates a light-emitting signal based on the reference current to drive the light-emitting device to emit light. Based on this, this application can control the pulse width and current magnitude of the light-emitting device without using other transistors, using only the driving transistor. Therefore, the pixel circuit in this application can not only reduce the voltage drop caused by the use of other transistors in the prior art, but also save the area occupied by other transistors in the prior art, thereby reducing the area occupied by the pixel circuit. With the reduction in the area occupied by the pixel circuit, the area occupied by the pixel array is also reduced.

[0097] Furthermore, in the embodiments of this application, the digital logic module can directly control the gate of the driving transistor through the switching module without the need for a level converter, thus further reducing the area occupied by the pixel array.

[0098] It should be understood, referring to Figure 4, that since each row of pixel units or each column of pixel units is connected to a reference transistor, there is inter-device capacitance among multiple pixel units. The Vg (Vg1_1, Vg1_2, Vg1_3) of multiple pixel units is shared. There is RC of the trace itself between the gates of the driving transistors. There will be built-in capacitance of the driving transistors between the gates and multiple pulse width modulation signals (EM1_1, EM1_2, EM1_3, EM2_1, EM2_2, EM2_3). The pulse width control timing diagram is shown in Figure 5, and the equivalent circuit diagram is shown in Figure 6.

[0099] Referring to Figures 5 and 6, the pixel array includes two rows or two columns of pixel units, and each row or column of pixel units includes three pixel units. It is worth noting that the number of rows and columns of the pixel array in this embodiment can also be other values, and this embodiment does not impose any special limitations on this.

[0100] Referring to Figure 5, the reference currents corresponding to the two rows or two columns of pixel units are Iref1 and Iref2. The pulse width modulation signals for the multiple pixel units are EM1_1, EM1_2, EM1_3, EM2_1, EM2_2, and EM2_3. If the pulse width modulation signals (EM1_1, EM1_2, EM1_3, EM2_1, EM2_2, EM2_3) of multiple pixel units simultaneously control the corresponding driving transistors to turn on, it is equivalent to all gates sharing the Vg signal (including but not limited to Vg1_1, Vg1_2, and Vg1_3) of the driving transistors in parallel, which is equivalent to the capacitance of the driving transistors being superimposed. Therefore, when the pulse width modulation signals in the pixel array control all driving transistors to turn on, the potential of the gate of the driving transistors will be coupled, resulting in the potential jump shown in Figure 7 (the spike part that appears in Vg1 and Vg2). When the pulse width modulation signals in the pixel array control all driving transistors to turn on, since the number of driving transistors turned on increases, the parallel capacitance increases, so the Vg (Vg1 and Vg2) potential shared by multiple driving transistors is pulled up. At the same time, because the superimposed capacitance is too large, the recovery of the Vg potential after it is pulled up is too slow, and the resulting effect is shown in Figure 8. When the gate potential of the driving transistor is coupled high, the output current of the driving transistor will decrease (the driving transistor is PMOS, Vg increases and Vgs decreases, so the output current decreases). If the pulse width modulation signal controlling the light-emitting device LL is a narrow pulse width, the current I_LL in the light-emitting device LL may not rise to the target value, and the brightness of the light-emitting device LL will not meet the requirements, and the grayscale control of the light-emitting device LL will fail.

[0101] Based on this, in the embodiments of this application, the above situation can be improved by controlling the turn-on time of the light-emitting device in the corresponding pixel unit to be different from the turn-on time of the light-emitting device in at least some other pixel units through the digital logic module.

[0102] Specifically, referring to Figure 9, the digital logic module outputs a pulse width modulation (PWM) signal. This signal, based on the different grayscale requirements of the light-emitting device, controls the driving transistors to turn on at different times and turn them off at a unified time, thus achieving pulse width control. Based on this, the number of driving transistors turned on simultaneously in the pixel array is reduced, and the parallel capacitor is also reduced accordingly. Therefore, the influence of the pulse width modulation signal's jump coupling on the gate voltage Vg of the driving transistor is greatly weakened. The output current of the PWM signal is shown in Figure 10. It can be seen that the current loss shown in Figure 8 does not occur at this time, enabling precise control of brightness by the pulse width. When the pulse width modulation signal controls the drive transistor to turn off, although the gate voltage of the drive transistor is coupled low (the large spike waveform part in Vg1 in Figure 10), as shown in Figure 4, the switching module is disconnected, and the Vg_rst signal is valid. The Vg_rst initialization voltage directly resets the gate of the drive transistor. Vg_rst is a DC reset voltage, directly forcing the gate voltage of the drive transistor to = Vg_rst (Vg_rst = ELVDD). Although the Vg signal is coupled low at this time, the transition of Vg will not be transmitted to Vg1. At this time, Vg1 = Vg_rst, and the drive transistor is completely turned off, which will not affect the brightness of the light emission (at this time, the pulse width control has ended, and the reset transistor directly resets the light-emitting device). Based on this, this embodiment can ensure that the brightness of the light-emitting device LL meets the requirements, so as to realize the grayscale control of the light-emitting device LL.

[0103] Thirdly, embodiments of this application also provide a display panel including the pixel array described in any of the second aspects.

[0104] The beneficial effects of the display panel in this embodiment are the same as those of the pixel array in the second aspect, and will not be repeated here.

[0105] Fourthly, embodiments of this application also provide a display device, including the display panel described in the third aspect.

[0106] The beneficial effects of the display device in this embodiment are the same as those of the display panel in the third aspect, and will not be repeated here.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A pixel circuit, characterized by comprising: The application relates to a pixel circuit for driving a light-emitting device. The pixel circuit comprises: a digital logic module for generating a pulse width modulation signal; a switch module connected to the digital logic module; a drive tube connected to the switch module; 2. The pixel circuit of claim 1, wherein, the digital logic module controls the switch module through the pulse width modulation signal to control the on-off of the drive tube, thereby controlling the brightness of the light-emitting device. The pixel circuit further comprises a reference tube connected to the drive tube through the switch module to form a current mirror circuit with the drive tube; 3. The pixel circuit of claim 2, wherein, the reference tube is used to provide a reference current to the drive tube when the switch module is turned on, and the drive tube replicates the reference current based on the current mirror principle to drive the light-emitting device.

4. The pixel circuit of claim 2, wherein, The drive tube is a PMOS tube, and the size of the reference current can be determined according to the width-length ratio of the reference tube and the drive tube. The switch module comprises a first switch unit connected to the digital logic module and the gate of the drive tube; 5. The pixel circuit of claim 4, wherein, the first switch unit is used to be turned on under the control of the pulse width modulation signal and provide the reference current output by the reference tube to the drive tube. The first switch unit comprises a first switch tube and a second switch tube; the gate of the first switch tube is connected to the digital logic module, the input terminal is connected to the reference tube, and the output terminal is connected to the gate of the drive tube, and the first switch tube is used to be turned on under the control of the pulse width modulation signal to provide the reference current output by the reference tube to the drive tube; 6. The pixel circuit of claim 4, wherein, the gate of the second switch tube is connected to the digital logic module, the input terminal is connected to a first reset voltage terminal, and the output terminal is connected to the gate of the drive tube, and the second switch tube is used to be turned on when the first switch tube is turned off by the pulse width modulation signal and provide a first reset voltage provided by the first reset voltage terminal to the gate of the drive tube; wherein the first reset voltage is used to turn off the drive tube. The first switch unit comprises a first transmission gate, a second transmission gate and an inverter; the input terminal of the inverter is connected to the digital logic module, and the output terminal is connected to the first transmission gate and the second transmission gate; the digital logic module is also connected to the first transmission gate and the second transmission gate; the first transmission gate is also connected to the gate of the reference tube and the drive tube, and is used to be closed under the control of the pulse width modulation signal to provide the reference current output by the reference tube to the drive tube; 7. The pixel circuit according to any one of claims 2 to 6, characterized in that, the second transmission gate is also connected to the first reset voltage terminal and the gate of the drive tube, and is used to be closed when the first transmission gate is turned off by the pulse width modulation signal and provide a first reset voltage provided by the first reset voltage terminal to the drive tube; wherein the first reset voltage is used to turn off the drive tube. The switch module further comprises a second switch unit connected to the digital logic module, the light-emitting device and a second reset voltage terminal, and is used to provide a second reset voltage output by the second reset voltage terminal to the light-emitting device when the drive tube is turned off under the control of the pulse width modulation signal, wherein the second reset voltage is used to turn off the light-emitting device.

8. The pixel circuit of claim 7, wherein, The second switch unit comprises a third switch tube; a gate of the third switch tube is connected with the digital logic module, an input pole is connected with a second reset voltage terminal, and an output pole is connected with the light emitting device, for being turned on under control of the pulse width modulation signal when the pulse width modulation signal controls the drive tube to be turned off, and providing the second reset voltage output by the second reset voltage terminal to the light emitting device.

9. The pixel circuit according to any one of claims 2 to 6, characterized in that, The voltage stabilizing module is further connected between the reference tube and the switch module, for providing a stable voltage between the reference tube and the switch module.

10. The pixel circuit of claim 9, wherein, The voltage stabilizing module comprises a capacitor, one end of the capacitor is connected with a voltage signal terminal, and the other end is connected between the reference tube and the switch module, for providing the stable voltage generated by the voltage signal terminal to between the reference tube and the switch module.

11. A pixel array, comprising: The display panel comprises: m rows and n columns of pixel units, and a reference tube connected with each row of the pixel units or each column of the pixel units; wherein each of the pixel units comprises the pixel circuit of any one of claims 1-10; The reference tube is connected with a switch module of the pixel unit in the corresponding row or column, for providing a reference current to the corresponding drive tube through the corresponding switch module.

12. The pixel array of claim 11, wherein, The digital logic module is used for controlling the opening time of the light emitting device driven by the corresponding pixel unit to be different from the opening time of the light emitting device driven by at least part of other pixel units.

13. A display panel, characterized by The display panel comprises the pixel array of claim 11 or 12.

14. A display device comprising: The display panel comprises the display panel of claim 13.

Images