Pixel driving circuit and method and display panel

Abstract

The invention discloses a pixel driving circuit and method and a display panel. The pixel driving circuit comprises a light-emitting unit, a first transistor, a second transistor, a driving transistor and a bistable trigger, a drain electrode of the first transistor, a source electrode of the second transistor and a grid electrode of the driving transistor are all connected with the bistable trigger, a first voltage is connected to the source electrode of the driving transistor, and the drain electrode is connected with the light-emitting unit. And the bistable trigger is also connected with a second voltage and loads the second voltage to the driving transistor based on the light emitting data signal when the first transistor is switched on, so that the driving transistor generates a driving current and drives the light emitting unit to emit light, and the first voltage and the second voltage both correspond to the color of the light emitting unit. According to the invention, displayed gray scales and colors can be processed separately, and the light-emitting units with different colors provide driving currents corresponding to the colors, so that display of all gray scales in various colors can be realized, white balance can also be considered, and the color display effect can be greatly improved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a pixel driving circuit, method and display panel. Background Art

[0002] Currently, digital driving is mainly used for monochrome array display driving of light-emitting diodes (LEDs), that is, the scanning time of each frame of display is divided into sub-fields of different sizes, and the light emission of each sub-field is controlled separately. The light emission time of each sub-field is combined to achieve the control of the total light emission time in this frame, thereby controlling the lighting time of each light-emitting unit in the display panel to achieve the effect of different grayscales for each light-emitting unit.

[0003] For a full-color array of light-emitting diodes, white light (W) is obtained by adding the three primary colors of red (R), green (G), and blue (B). In order to achieve RGB full-color display, if the existing digital driving method is continued to be used, that is, the driving current of each color pixel is kept unchanged, and only the light-emitting time of each color pixel is controlled separately, the number of grayscales of red pixels and blue pixels will be small, or white balance cannot be achieved, thereby failing to achieve a good color display effect. Summary of the invention

[0004] The embodiments of the present application provide a pixel driving circuit, method and display panel to solve the technical problem that the existing driving method cannot achieve a good color display effect.

[0005] In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

[0006] In a first aspect, a pixel driving circuit is provided, which is applied to a display panel, comprising:

[0007] Light emitting unit;

[0008] a first transistor, wherein a source of the first transistor is connected to a light emitting data signal, a gate of the first transistor is connected to a row scanning signal, and a drain of the first transistor is electrically connected to a bistable trigger;

[0009] a second transistor, wherein a source of the second transistor is electrically connected to the bistable trigger, a gate of the second transistor is connected to a row clear signal, and a drain of the second transistor is electrically connected to a drain of the first transistor;

[0010] A driving transistor; the gate of the driving transistor is electrically connected to the bistable trigger, the source of the driving transistor is connected to a first voltage, and the drain of the driving transistor is electrically connected to the anode of the light-emitting unit;

[0011] In which, the bistable trigger is also connected to a second voltage, and based on the row scan signal and the light-emitting data signal, when the second voltage is loaded to the gate of the driving transistor, the driving transistor generates a driving current according to the first voltage and the second voltage and drives the light-emitting unit to emit light, and the first voltage and the second voltage both correspond to the color of the light-emitting unit.

[0012] In combination with the first aspect, the color of the light emitting unit is any one of red, green and blue;

[0013] The driving current generated by the driving transistor connected to the red light-emitting unit, the driving current generated by the driving transistor connected to the green light-emitting unit, and the driving current generated by the driving transistor connected to the blue light-emitting unit have a ratio of a:b:c, satisfying: a:b:c is equal to the ratio between the red light flux, green light flux and blue light flux corresponding to white light under the color coordinates corresponding to the display panel.

[0014] In combination with the first aspect, the bistable trigger includes a third transistor, a fourth transistor, a fifth transistor and a sixth transistor;

[0015] The source of the third transistor and the source of the fifth transistor are both electrically connected to a first input port, the first input port is connected to a third voltage, the drain of the third transistor and the drain of the fourth transistor are both electrically connected to the drain of the first transistor, the gate of the third transistor is electrically connected to the gate of the fourth transistor, a first node is provided on a connection line between the gate of the third transistor and the gate of the fourth transistor, the source of the fourth transistor and the source of the sixth transistor are both electrically connected to a second input port, the second input port is connected to the second voltage, and the source of the fourth transistor is also electrically connected to the source of the second transistor;

[0016] The gate of the fifth transistor and the gate of the sixth transistor are both electrically connected to the drain of the first transistor, the drain of the fifth transistor is electrically connected to the drain of the sixth transistor, a second node is arranged on the connecting line between the drain of the fifth transistor and the drain of the sixth transistor, the first node is electrically connected to the second node, the second node is electrically connected to an output port, and the output port is electrically connected to the gate of the driving transistor.

[0017] In combination with the first aspect, the third transistor, the fifth transistor and the driving transistor are P-type transistors, and the first transistor, the second transistor, the fourth transistor and the sixth transistor are N-type transistors.

[0018] In combination with the first aspect, the source of the driving transistor is electrically connected to the third input port, the third input port is configured to be electrically connected to a first power supply module through a first signal line, and the first power supply module is configured to provide the first voltage corresponding to the color of the light-emitting unit;

[0019] The second input port is configured to be electrically connected to a second power supply module through a second signal line, and the second power supply module is configured to provide the second voltage corresponding to the color of the light-emitting unit;

[0020] Among them, the first signal line corresponding to the red light-emitting unit, the first signal line corresponding to the green light-emitting unit, and the first signal line corresponding to the blue light-emitting unit are arranged in different layers of the display panel; and / or, the second signal line corresponding to the red light-emitting unit, the second signal line corresponding to the green light-emitting unit, and the second signal line corresponding to the blue light-emitting unit are arranged in different layers of the display panel.

[0021] In combination with the first aspect, when the driving transistor operates in a saturation region, the first voltage, the second voltage, and the driving current satisfy the following corresponding relationship:

[0022]

[0023] Among them, I ds is the driving current, μ is the mobility of the driving transistor, C ox is the unit area capacitance of the gate oxide layer of the driving transistor, W is the channel width of the driving transistor, L is the channel length of the driving transistor, V gs is the difference between the first voltage and the second voltage, V h is the threshold voltage of the driving transistor.

[0024] In a second aspect, a pixel driving method is provided, for driving the pixel driving circuit according to any one of the first aspects, the method comprising:

[0025] Based on the input row scanning signal, the first transistor transmits the received light emitting data signal to the bistable trigger when it is turned on;

[0026] Based on the light emitting data signal, the bistable trigger loads the received second voltage to the gate of the driving transistor according to a set timing, so as to turn on the driving transistor;

[0027] The driving transistor generates a driving current according to a first voltage received by a source and a second voltage received by a gate, wherein the first voltage and the second voltage both correspond to the color of the light-emitting unit;

[0028] The light emitting unit is driven to emit light based on the driving current and the on-time of the driving transistor.

[0029] In combination with the second aspect, the color of the light emitting unit is any one of red, green and blue;

[0030] The driving current received by the red light-emitting unit, the driving current received by the green light-emitting unit and the driving current received by the blue light-emitting unit have a ratio of a:b:c, satisfying: a:b:c is equal to the ratio between the red light flux, green light flux and blue light flux corresponding to the white light under the color coordinates corresponding to the display panel.

[0031] In combination with the second aspect, when the driving transistor operates in a saturation region, the first voltage, the second voltage, and the driving current satisfy the following corresponding relationship:

[0032]

[0033] Among them, I ds is the driving current, μ is the mobility of the driving transistor, C ox is the unit area capacitance of the gate oxide layer of the driving transistor, W is the channel width of the driving transistor, L is the channel length of the driving transistor, V gs is the difference between the first voltage and the second voltage, V h is the threshold voltage of the driving transistor.

[0034] In a third aspect, a display panel is provided, comprising a pixel driving circuit as described in any one of the first aspects.

[0035] One of the above technical solutions has the following advantages or beneficial effects:

[0036] Compared with the prior art, a pixel driving circuit of the present application includes a light-emitting unit, a first transistor, a second transistor, a driving transistor and a bistable trigger, wherein the source of the first transistor is connected to a light-emitting data signal, the gate is connected to a row scanning signal, the drain is connected to the bistable trigger, the source of the second transistor is connected to the bistable trigger, the gate is connected to a row clear signal, the drain is connected to the drain of the first transistor, the gate of the driving transistor is connected to the bistable trigger, the source is connected to a first voltage, the drain is connected to the light-emitting unit, the bistable trigger is also connected to a second voltage, and based on the row scanning signal and the light-emitting data signal, the second voltage is loaded to the driving transistor so that the driving transistor generates a driving current and drives the light-emitting unit to emit light, wherein the first voltage and the second voltage both correspond to the color of the light-emitting unit. The pixel driving circuit provided by the present application can process the grayscale and color displayed by the light-emitting unit separately, and light-emitting units of different colors provide driving currents corresponding to the colors, so that light-emitting units of various colors can realize the display of all grayscales, and can also take into account white balance, which can greatly improve the color display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 A schematic diagram showing an example of a traditional color display effect of a display panel;

[0039] Figure 2 A schematic diagram of a specific structure of a display panel according to an embodiment of the present application;

[0040] Figure 3 This is a schematic diagram of the overall structure of a pixel driving circuit according to an embodiment of the present application;

[0041] Figure 4 This is a schematic diagram of the structure of the first power module in an embodiment of the present application;

[0042] Figure 5 This is a schematic diagram of the structure of the second power supply module in an embodiment of the present application;

[0043] Figure 6 A schematic diagram of a sub-field processing method for data to be displayed according to an embodiment of the present application;

[0044] Figure 7 A schematic diagram of a sub-field scanning timing sequence of an embodiment of the present application;

[0045] Figure 8A schematic diagram of the structure of a column scanning circuit in a display panel according to an embodiment of the present application;

[0046] Fig. 9 This is a schematic diagram showing an example of the color display effect of the display panel according to an embodiment of the present application;

[0047] Fig.10 The figure is a schematic diagram of the overall process of a pixel driving method according to an embodiment of the present application.

[0048] Reference numerals:

[0049] 100-light-emitting unit; 200-pixel driving circuit; 201 first input port; 202-second input port; 203-third input port; 210-first transistor; 220-second transistor; 230-driving transistor; 240-bistable trigger; 241-output port; 300-power module; 310-first power module; 311-first power submodule; 320-second power module; 321-second power submodule; 3211-voltage adjustable circuit; 3212-level converter; 330-third power module; 301-first signal line; 302-second signal line; 400-timing controller; 500-data processor; 600-column scanning circuit; 610-data line; 700-row scanning circuit; 710-scanning line. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. In the description of the present application, it is necessary to understand that the orientation or position relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0051] In the present application, the display panel may be, but is not limited to, a color silicon-based micro LED (Micro Light Emitting Diode) display panel, a color silicon-based OLED (Organic Light-Emitting Diode) display panel, a vehicle-mounted color micro LED display panel, a mini LED (Mini Light Emitting Diode) display panel, an LED (Light-Emitting Diode) display panel, etc. Different types of display panels include corresponding types of light-emitting unit arrays.

[0052] The applicant noted that the current pixel driving circuit mainly includes two driving modes, analog driving and digital driving, in terms of grayscale realization. Analog driving is to adjust the luminous brightness of the light-emitting unit by adjusting the driving current flowing through the light-emitting unit, and digital driving is to adjust the luminous brightness of the light-emitting unit by adjusting the luminous time of the light-emitting unit. Compared with analog driving, each grayscale corresponds to a data voltage, that is, one data voltage corresponds to a luminous brightness of the light-emitting unit. The working state of the light-emitting unit in the digital driving circuit only includes a bright state and a dark state, wherein the working timing of the digital driving circuit includes a "1" state timing and a "0" state timing, the "1" state corresponds to the bright state of the light-emitting unit, and the "0" state corresponds to the dark state of the light-emitting unit. Digital driving realizes grayscale control by controlling the length of the light-emitting time of the light-emitting unit (that is, the duration of the bright state and the duration of the dark state).

[0053] Since the wavelength of the R (red) / G (green) / B (blue) LED will change according to the size of the driving current, and when the LED is driven by a small current, the brightness difference between each LED will be large, which will cause serious uneven display. This phenomenon is more serious when the LED is of a tiny size. Therefore, at present, digital driving is still more commonly used for micro LED driving to avoid the above display problems. Digital driving mainly divides the scanning time of each frame of the display screen into sub-fields of different sizes, and controls the light emission of each sub-field separately. The light emission time of each sub-field is combined to achieve the control of the total light emission time in this frame, thereby controlling the lighting time of each light-emitting unit in the display panel to achieve the effect of different grayscales for each light-emitting unit.

[0054] However, with the increasing requirements for resolution, frame rate and display grayscale, even for monochrome array displays, the clock frequency requirements of this driving scheme have reached a peak level. If RGB full-color array display is realized based on this scheme, the corresponding R / G / B full grayscale requirements will be difficult to achieve. This is because in full-color display, white light (W) is obtained by adding the three primary colors of red (R), green (G) and blue (B). In order to achieve white balance, the luminous flux ratio of R / G / B is certain under fixed color coordinate specifications.

[0055] See also Figure 1 , Figure 1 The conventional color display effect example of the display panel is shown. For example, under the color coordinate specifications of W (0.300, 0.315), R (0.682, 0.317), G (0.250, 0.710), and B (0.138, 0.051), the luminous flux ratio of R / G / B is ΦR:ΦG:ΦB=3.18:9.27:1. To achieve a white screen with L255 grayscale and a brightness of 1000 nits (brightness unit), the brightness of R / G / B needs to be 236 nits, 689 nits, and 74 nits, respectively, among which the green luminous flux ratio is the largest, and the blue luminous flux ratio is the smallest. In L255 grayscale, if the driving current of R / G / B light-emitting units is the same, due to the different luminous efficiency of each color, the luminous flux required for each color combination under white balance is also different. Assuming that the green light-emitting unit requires the longest luminous time, and the red / blue light-emitting unit requires a shorter luminous time, then the following will appear under white balance. Figure 1 As shown, the luminous duration corresponding to the green light emitting unit (G LED) L255 fully occupies the effective luminous time of each sub-field in one frame, while the luminous duration corresponding to the red light emitting unit (R LED) and the blue light emitting unit (B LED) L255 is shorter. Therefore, it is difficult to divide 256 grayscales in these fewer sub-fields by continuing to use the existing digital driving method, resulting in a small number of grayscales of the red / blue light emitting unit, which cannot meet the requirement of 256 grayscales, or the problem of being unable to achieve white balance occurs, and thus a good color display effect cannot be achieved.

[0056] In view of this, an embodiment of the present application provides a pixel driving circuit applied to a display panel, which separately processes the grayscale and color displayed by the light-emitting unit, and provides driving currents corresponding to the colors for light-emitting units of different colors. In this way, the light-emitting durations required for the light-emitting units of the three colors of RGB at the same grayscale are consistent, and by controlling the corresponding light-emitting durations, each color can achieve the display effects of all grayscales.

[0057] See also Figure 2 , Figure 2The specific structure of the display panel of the embodiment of the present application is illustrated. The display panel generally includes a timing controller 400, a data processor 500, a column scanning circuit 600, a row scanning circuit 700, and a plurality of pixel driving circuits 200 located in the display area and arranged in an array. The timing controller 400 is configured to generate various timing signals. The data processor 500 is connected to the timing controller 400, and is configured to receive data to be displayed and corresponding timing signals, and to generate a first data signal data (0 / 1) based on the data to be displayed and the timing signal. The column scanning circuit 600 is respectively connected to the data processor 500 and the plurality of pixel driving circuits 200, and is configured to generate a second data signal Data (0 / 1), that is, a light-emitting data signal, based on the received first data signal data (0 / 1), and transmit the light-emitting data signal to the corresponding pixel driving circuit 200 through the data line 610. The row scanning circuit 700 is connected to the timing controller 400 and the plurality of pixel driving circuits 200, respectively, and is configured to generate a row scanning signal Scan and a row clearing signal Clear based on the scanning signal, and transmit the row scanning signal and the row clearing signal to the corresponding pixel driving circuit 200 through the scanning line 710. Each pixel driving circuit 200 may be disposed in a space formed by the intersection of the scanning line 710 and the data line 610.

[0058] In addition, the pixel driving circuit 200 may also be connected to a power module 300, and the power module 300 is used to provide the required voltage for the pixel driving circuit 200. The power module 300 may include a first power module 310, a second power module 320 and a third power module 330. The first power module 310 may be configured to provide a first voltage V LED , the second power module 320 can be configured to provide a second voltage V GL , the third power supply module 330 may be configured to provide a third voltage V GH In addition, the power supply module 300 may further include a reference power supply module and a ground power supply module to provide a reference voltage V to the corresponding pixel driving circuit 200 respectively. ref It is understandable that the power module 300 may also be an integral device and have multiple interfaces, each of which may be electrically connected to the corresponding pixel driving circuit 200 to output different voltages through different interfaces, as long as the function of providing different output voltages can be achieved, and the embodiment of the present application does not specifically limit this.

[0059] The pixel driving circuit 200 according to the embodiment of the present application is described below.

[0060] See also Figure 3 , Figure 3The overall structure of the pixel driving circuit of the embodiment of the present application is illustrated. The pixel driving circuit 200 includes a light-emitting unit 100, a first transistor 210, a second transistor 220, a driving transistor 230 and a bistable trigger 240. The source of the first transistor 210 is connected to the light-emitting data signal, the gate of the first transistor 210 is connected to the row scanning signal, and the drain of the first transistor 210 is electrically connected to the bistable trigger 240. The source of the second transistor 220 is electrically connected to the bistable trigger 240, the gate of the second transistor 220 is connected to the row clear signal, and the drain of the second transistor 220 is electrically connected to the drain of the first transistor 210. The gate of the driving transistor 230 is electrically connected to the bistable trigger 240, and the source of the driving transistor 230 is connected to the first voltage V LED , the drain of the driving transistor 230 is electrically connected to the anode of the light emitting unit 100. The bistable trigger 240 is also connected to the second voltage V GL , and based on the row scan signal and the light emitting data signal, the second voltage V GL When the gate of the driving transistor 230 is loaded, the driving transistor 230 is driven according to the first voltage V LED and the second voltage V GL Generates a driving current and drives the light-emitting unit 100 to emit light. The first voltage V LED and the second voltage V GL All correspond to the colors of the light emitting unit 100 .

[0061] Specifically, the first transistor 210 is turned on when the row scan signal Scan addresses the pixel driving circuit 200 row by row, and stores the light emitting data signal on the bistable trigger 240. The second transistor 220 clears the data on the bistable trigger 240 when the row clear signal Clear addresses the pixel driving circuit 200 row by row. The driving transistor 230 switches the anode of the light emitting unit 100 corresponding to the switch to the first voltage V according to the data level on the bistable trigger 240. LED , all the light-emitting units 100 have a common cathode connected to a ground voltage VSS to control the light-emitting unit 100 to light up and turn off.

[0062] In some examples, the color of the light emitting unit 100 is any one of red, green and blue. The driving current I generated by the driving transistor 230 connected to the red light emitting unit 100 is dsR , the driving current I generated by the driving transistor 230 connected to the green light emitting unit 100 dsG The driving current I generated by the driving transistor 230 connected to the blue light emitting unit 100 dsB There is a ratio a:b:c between them, satisfying: a:b:c is equal to the ratio between the red light flux, the green light flux and the blue light flux corresponding to the white light under the color coordinates corresponding to the display panel.

[0063] For example, under the color coordinate specifications of W (0.300, 0.315), R (0.682, 0.317), G (0.250, 0.710), and B (0.138, 0.051), the luminous flux ratio of R / G / B ΦR:ΦG:ΦB=3.18:9.27:1, then the driving currents I corresponding to the three colors are dsR ,I dsG and I dsB The ratio between them is a:b:c=3.18:9.27:1.

[0064] Specifically, the luminous flux is the integral of the luminous intensity (instantaneous) and the luminous duration. The luminous intensity (instantaneous) is proportional to the driving current, and is the product of the driving current and the luminous efficiency of the light-emitting unit. The luminous efficiency is fixed under a fixed driving current. Therefore, first, the luminous flux of each color can be determined according to the maximum display brightness of the display panel and the luminous flux ratio of R / G / B under the corresponding color coordinate specification. Then, the luminous intensity (instantaneous) of each color can be determined according to the luminous flux of each color and the maximum luminous duration. Finally, the driving current corresponding to each color can be determined according to the luminous intensity (instantaneous) and luminous efficiency of each color. Specifically, the parameter calculation can be performed according to the conversion relationship of the relevant technology, which will not be elaborated in the embodiments of the present application.

[0065] In this way, different driving currents are provided for light-emitting units 100 of different colors, and the fixed ratio of the driving currents of different colors satisfies the color ratio of white light under the color coordinates corresponding to the display panel, so that the light-emitting units of the three colors of red, green and blue can all display all gray levels and take into account white balance, which can greatly improve the color display effect.

[0066] Please continue reading Figure 2 In some embodiments, the bistable trigger 240 may include a third transistor T1, a fourth transistor T2, a fifth transistor T3 and a sixth transistor T4. The third transistor T1, the fourth transistor T2, the fifth transistor T3 and the sixth transistor T4 form two inverters and are cross-coupled to form the bistable trigger 240.

[0067] Specifically, the source of the third transistor T1 and the source of the fifth transistor T3 are both electrically connected to the first input port 201, and the first input port 201 is configured to receive the third voltage V GHThe drain of the third transistor T1 and the drain of the fourth transistor T2 are both electrically connected to the drain of the first transistor 210, the gate of the third transistor T1 is electrically connected to the gate of the fourth transistor T2, a first node A is provided on the connection line between the gate of the third transistor T1 and the gate of the fourth transistor T2, the source of the fourth transistor T2 and the source of the sixth transistor T4 are both electrically connected to the second input port 202, and the second input port 202 is configured to be connected to the second voltage V GL , the source of the fourth transistor T2 is also electrically connected to the source of the second transistor 220 .

[0068] The gate of the fifth transistor T3 and the gate of the sixth transistor T4 are both electrically connected to the drain of the first transistor 210, the drain of the fifth transistor T3 is electrically connected to the drain of the sixth transistor T4, a second node B is arranged on the connecting line between the drain of the fifth transistor T3 and the drain of the sixth transistor T4, the first node A is electrically connected to the second node B, the second node B is electrically connected to the output port 241, and the output port 241 is electrically connected to the gate of the driving transistor 230.

[0069] Exemplarily, the third transistor T1 , the fifth transistor T3 , and the driving transistor 230 are P-type transistors, and the first transistor 210 , the second transistor 220 , the fourth transistor T2 , and the sixth transistor T4 are N-type transistors.

[0070] Specifically, the working process of the bistable trigger 240 is as follows: the light emitting data signal is first loaded onto the Data line and transmitted to the source of the first transistor 210. When the row scanning signal becomes a valid signal, the first transistor 210 is turned on, and the light emitting data signal is loaded onto the bistable trigger 240 to hold the signal. When the light emitting data signal Data is "1", the sixth transistor T4 is turned on, and the second voltage V GL The third voltage V GH The voltage is loaded to the gate of the driving transistor 230 , and the driving transistor 230 is turned off, and the light-emitting unit 100 does not emit light.

[0071] In some examples, the driving transistor 230 can be designed to operate in the saturation region, that is, |V gs -V th |<|V ds |, where V gs is the second voltage V GL With the first voltage V LED The difference, V th is the threshold voltage of the driving transistor 230, V dsis the voltage difference between the drain and source of the driving transistor 230. Then the driving current received by the corresponding light-emitting unit 100 is equal to the first voltage V LED and the second voltage V GL The following corresponding relationship is satisfied:

[0072]

[0073] Among them, I ds is the driving current, μ is the mobility of the driving transistor 230, C ox is the unit area capacitance of the gate oxide layer of the driving transistor 230, W is the channel width of the driving transistor 230, L is the channel length of the driving transistor 230, V gs is the second voltage V GL With the first voltage V LED The difference, V gs =V GL -V LED ; V th is the threshold voltage of the driving transistor 230 .

[0074] Through the above example, the driving current I ds The magnitude of the second voltage V GL Or the first voltage V LED To make adjustments, the adjustments are relatively simple and easy to implement.

[0075] In some other examples, the driving transistor 230 may be designed to operate in a mid-linear region, i.e., |V gs -V th |>|V ds |, where V gs is the second voltage V GL With the first voltage V LED The difference, V th is the threshold voltage of the driving transistor 230, V ds is the voltage difference between the drain and source of the driving transistor 230. Then the driving current received by the corresponding light-emitting unit 100 is equal to the first voltage V LED and the second voltage V GL The following corresponding relationship is satisfied:

[0076]

[0077] Among them, I ds is the driving current, μ is the mobility of the driving transistor 230, C ox is the unit area capacitance of the gate oxide layer of the driving transistor 230, W is the channel width of the driving transistor 230, L is the channel length of the driving transistor 230, V gs is the second voltage V GLWith the first voltage V LED The difference, V gs =V GL -V LED ; V th is the threshold voltage of the driving transistor 230, V ds is the voltage difference between the drain and source of the driving transistor 230 .

[0078] Please also read Figure 2 and Figure 3 In some embodiments, the source of the driving transistor 230 is electrically connected to the third input port 203, and the third input port 203 is configured to be electrically connected to the first power module 310 through the first signal line 301, and the first power module 310 is configured to provide a first voltage corresponding to the color of the light-emitting unit 100. The second input port 202 is configured to be electrically connected to the second power module 320 through the second signal line 302, and the second power module 320 is configured to provide a second voltage corresponding to the color of the light-emitting unit 100.

[0079] Among them, the first signal line 301 corresponding to the red light-emitting unit 100, the first signal line 301 corresponding to the green light-emitting unit 100, and the first signal line 301 corresponding to the blue light-emitting unit 100 are arranged in different layers of the display panel. And / or, the second signal line 302 corresponding to the red light-emitting unit 100, the second signal line 302 corresponding to the green light-emitting unit 100, and the second signal line 302 corresponding to the blue light-emitting unit 100 are arranged in different layers of the display panel. In this way, it is not only convenient to route, but also can avoid mutual interference between signals corresponding to different colors, thereby improving the quality of signal transmission.

[0080] It should be noted that in order to better reflect the first signal line 301 and the second signal line 302 corresponding to the light emitting units 100 of different colors, Figure 2 In the figure, different line types are used to distinguish the first signal line 301 and the second signal line 302 corresponding to the light-emitting units 100 of different colors.

[0081] In some examples, the first signal line 301 may include a first sub-signal line and a second sub-signal line arranged to intersect, wherein the first sub-signal line extends along a first direction X of the display panel, and the second sub-signal line extends along a second direction Y of the display panel. The second signal line 302 may include a third sub-signal line and a fourth sub-signal line arranged to intersect, wherein the third sub-signal line extends along the first direction X of the display panel, and the fourth sub-signal line extends along the second direction Y of the display panel.

[0082] Please also refer to Figure 4 and Figure 5 , Figure 4The structure of the first power module in the embodiment of the present application is illustrated. Figure 5 The structure of the second power module in the embodiment of the present application is illustrated. In some examples, the first power module 310 may include three first power submodules 311, each of which may be connected to the third input port 203 in the pixel driving circuit 200 driving the light emitting unit 100 of the corresponding color, so as to provide a first voltage V corresponding to the color of the light emitting unit 100. LED The second power module 320 may include three second power submodules 321, each of which may be connected to a second input port 202 in the pixel driving circuit 200 that drives the light emitting unit 100 of a corresponding color, so as to provide a second voltage V corresponding to the color of the light emitting unit 100. GL . In this way, the power module 300 can provide corresponding input voltages according to the driving current required by the connected light-emitting unit 100, thereby meeting the current proportionality requirement, and the implementation is relatively simple. It can be understood that the power module 300 can also be an integral device and have multiple interfaces, each of which can be electrically connected to the corresponding pixel driving circuit 200 to output different voltages through different interfaces. As long as the function of providing different input voltages to light-emitting units 100 of different colors can be realized, the embodiments of the present application do not make specific limitations on this.

[0083] Exemplarily, each second power submodule 321 may include a voltage adjustable circuit 3211 and a level converter 3212 connected to the voltage adjustable circuit 3211, and the level converter 3212 is connected to the second input port 202 of the pixel driving circuit 200. In this way, the level converter 3212 can flexibly adjust the voltage output by the voltage adjustable circuit 3211 as needed, thereby reducing the difficulty of voltage regulation.

[0084] Please also read Figure 6 and Figure 7 , Figure 6 A subfield processing method of data to be displayed in an embodiment of the present application is illustrated. Figure 7 A subfield scanning timing diagram of an embodiment of the present application is illustrated. The data to be displayed corresponding to each light-emitting unit can constitute a data stream to be displayed. After the data stream to be displayed enters the data processor 500, the data processor 500 extracts the grayscale information of each RGB color in the data stream to be displayed, and then processes it into data information of each subfield respectively, and then scans each subfield and writes the data signal according to the subfield scanning timing provided by the row scanning circuit 700. Among them, the signal given to the column scanning circuit 600 after the data processing is completed is a digital signal with only state "0" or "1".

[0085] For example, taking the grayscale accuracy of 8 bits as an example, the period of one frame can be divided into 8 subfields, namely SF1 to SF8. Taking four light-emitting units as an example, the corresponding grayscales are 128, 64, 0 and 200 respectively. Then, after each grayscale is represented in binary form, the grayscale values ​​of the four pixels corresponding to each subfield are extracted in parallel and converted into a serial manner. The data corresponding to SF1 is 0000, the data corresponding to SF2 is 0000, the data corresponding to SF3 is 0000, the data corresponding to SF4 is 0001, the data corresponding to SF5 is 0000, the data corresponding to SF6 is 0000, the data corresponding to SF7 is 0101, and the data corresponding to SF8 is 1001. Finally, according to Figure 6 The sub-field scanning timing shown is used to perform sub-field scanning and write data signals respectively. Figure 6 In the figure, Gate1~GateN are row scan signals of each row, CLR1~CLRN are row clear signals of each row, N is the total number of rows or columns of light-emitting units set in the display panel array, DATA(0), DATA(4), DATA(128) are data signals corresponding to grayscales, and DATA is the first data signal of each subfield.

[0086] The duration of the light-emitting phase of each subfield is different, that is, the lighting duration of the light-emitting unit is different. The setting method can be a standard binary weighted value increment or a non-standard binary weighted value increment. In the standard binary weighted value increment method, the ratio of the duration of the light-emitting phase of each subfield is 1(2 0 ):2(2 1 ):4(2 2 ):8(2 3 ):16(2 4 ):32(2 5 ):64(2 6 ):128(2 7 ). In this way, one frame of display data is the superposition of the display grayscale of each subfield, so that it can be displayed as 255 grayscale. It should be noted that in the embodiment of the present application, in order to improve the luminous brightness of the light-emitting unit L255 grayscale, when the scanning signal scans each row of light-emitting units, the light-emitting units in each row can emit light immediately after the addressing scanning time, and each light-emitting unit can continue to emit light during the driving time of the entire frame display picture.

[0087] For example, to achieve 256-level grayscale adjustment of a single green Micro-LED array with a display frequency of 60Hz and a resolution of 1280x1024, 8 subfields (recorded as subfields 1 to 8) form a frame, and the ratio of the luminous area width (i.e., the duration of the luminous stage) of the 8 subfields is set to 1:2:4:8:16:32:64:128, and the Data input to the 8 subfields is recorded as d1 to d8. Then the grayscale calculation method of the display screen is: Grayscale (Gray) = 1×d1+2×d2+4×d3+8×d4+16×d5+32×d6+64×d7+128×d8. When the Data input to subfield m is high, dm=1; when the Data input to the subfield is low, dm=0. When the Data input to all subfields is at a high level, d1 to d8 are all 1, and Gray=256; when the Data input to all subfields is at a low level, d1 to d8 are all 0, and Gray=0.

[0088] See also Figure 8 , Figure 8 The structure of the column scanning circuit in the display panel of the embodiment of the present application is illustrated. The column scanning circuit 600 of the embodiment of the present application includes a shift register shift, a latch latch and a level converter levelshift connected in sequence. The number of paths formed by the shift register shift, the latch latch and the level converter levelshift is the same as the number of columns of the light-emitting unit array in the display panel, wherein the shift register shift receives a reset signal Reset, a clock signal sclk and a first data signal data (0 / 1) respectively, and the latch latch also receives a clock signal lclk. The shift register shift and the latch latch can complete the serial-to-parallel conversion of the data, and the level converter levelshift can convert the potential corresponding to the "0" or "1" state into two potentials of turning off the light-emitting unit drive tube and turning on the light-emitting unit drive tube.

[0089] In combination with the above description, the overall working process of the display panel of the embodiment of the present application is as follows: the data stream to be displayed enters the data processor 500, the timing controller 400 generates a corresponding timing signal according to the set scanning algorithm to supply the row scanning circuit 700, and generates a corresponding timing signal to provide the data processor 500 with the timing required for data processing, and then the data processor 500 generates a first data signal according to the data stream to be displayed and the timing signal and transmits it to the column scanning circuit 600. At the same time, two groups of signals can be generated through the row scanning circuit 700, corresponding to the row scanning signal Scan and the row clearing signal Clear, which are respectively connected to the gates of the first transistor 210 and the second transistor 220, and the light emitting data signal output by the column scanning circuit 600 is connected to the source of the first transistor 210.

[0090] See also Fig. 9 , Fig. 9 An example of the color display effect of the display panel of the embodiment of the present application is illustrated. The driving system of the embodiment of the present application is used to drive the display panel to emit light, and the ratio a:b:c of the driving current of the three colors B / R / G satisfies the ratio of the luminous flux of B color / R color / G color constituting the white light W under the fixed W / R / G / B color coordinate specification. The light-emitting time required by the light-emitting units of each color at each gray scale is consistent, and full gray scale display can be achieved by only adjusting the light-emitting time.

[0091] It can be understood that the pixel driving circuit provided in the embodiment of the present application can control the color and grayscale separately, adopt the digital sub-field scanning method to control the display grayscale of the light-emitting unit, and match the current of the light-emitting units of different colors in a fixed ratio so that the ratio of the luminous flux of different colors just meets the ratio of white light, so that the digital driving part only needs to complete the full grayscale of the number of monochrome resolution columns × 3 to achieve the full grayscale effect of the full-screen color RGB. Not only is the logic of the digital driving architecture relatively simple and easy to implement, but it can also achieve better color display effects.

[0092] Accordingly, see Fig.10 , Fig.10 The overall process of a pixel driving method according to an embodiment of the present application is illustrated. The pixel driving method provided by the embodiment of the present application is used to drive a pixel driving circuit. Specifically, the method comprises the following steps:

[0093] 1001: Based on the input row scan signal, the first transistor transmits the received light-emitting data signal to the bistable trigger when it is turned on.

[0094] 1002: Based on the light emitting data signal, the bistable trigger loads the received second voltage to the gate of the driving transistor according to the set timing, so as to turn on the driving transistor.

[0095] 1003: The driving transistor generates a driving current according to a first voltage received by a source and a second voltage received by a gate.

[0096] The first voltage and the second voltage both correspond to the color of the light emitting unit.

[0097] In some examples, the color of the light emitting unit is any one of red, green and blue. The driving current received by the red light emitting unit, the driving current received by the green light emitting unit and the driving current received by the blue light emitting unit have a ratio a:b:c, satisfying: a:b:c is equal to the ratio of the red light flux, the green light flux and the blue light flux corresponding to the white light under the color coordinates corresponding to the display panel.

[0098] In some examples, when the driving transistor operates in a saturation region, the first voltage, the second voltage, and the driving current satisfy the following corresponding relationship:

[0099]

[0100] Among them, I ds is the driving current, μ is the mobility of the driving transistor, C ox is the unit area capacitance of the gate oxide layer of the driving transistor, W is the channel width of the driving transistor, L is the channel length of the driving transistor, V gs is the difference between the first voltage and the second voltage, V h is the threshold voltage of the driving transistor.

[0101] 1004: Based on the driving current and the on-time of the driving transistor, drive the light-emitting unit to emit light.

[0102] It can be understood that the pixel driving method of the embodiment of the present application can process the grayscale and color displayed by the light-emitting unit separately, and light-emitting units of different colors provide different driving currents, so that the fixed ratio of the driving currents of different colors can meet the color ratio of white light under the color coordinates corresponding to the display panel, thereby making the light-emitting units of the three colors of red, green and blue can all realize the display of all grayscales, and can also take into account the white balance, which can greatly improve the color display effect.

[0103] Correspondingly, an embodiment of the present application further provides a display panel, which includes the pixel driving circuit as described in the above embodiment.

[0104] It can be understood that the display panel of the embodiment of the present application can process the grayscale and color displayed by the light-emitting unit separately, and light-emitting units of different colors provide different driving currents, so that the fixed ratio of the driving currents of different colors can satisfy the color ratio of white light under the color coordinates corresponding to the display panel, so that the light-emitting units of the three colors of red, green and blue can all realize the display of all grayscales, and can also take into account the white balance, which can greatly improve the color display effect.

[0105] The above is a detailed introduction to a pixel driving circuit, method and display panel provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A pixel driving circuit, applied to a display panel, characterized in that: include: A light emitting unit (100); A first transistor (210), wherein a source of the first transistor (210) is connected to a light emitting data signal, a gate of the first transistor (210) is connected to a row scanning signal, and a drain of the first transistor (210) is electrically connected to a bistable trigger (240); a second transistor (220), wherein the source of the second transistor (220) is electrically connected to the bistable trigger (240), the gate of the second transistor (220) is connected to a row clear signal, and the drain of the second transistor (220) is electrically connected to the drain of the first transistor (210); A driving transistor (230); the gate of the driving transistor (230) is electrically connected to the bistable trigger (240), the source of the driving transistor (230) is connected to a first voltage, and the drain of the driving transistor (230) is electrically connected to the anode of the light-emitting unit (100); The bistable trigger (240) is also connected to a second voltage, and based on the row scan signal and the light-emitting data signal, when the second voltage is loaded to the gate of the driving transistor (230), the driving transistor (230) generates a driving current according to the first voltage and the second voltage and drives the light-emitting unit (100) to emit light, and the first voltage and the second voltage both correspond to the color of the light-emitting unit (100).

2. The pixel driving circuit according to claim 1, characterized in that: The color of the light-emitting unit (100) is any one of red, green and blue; The driving current generated by the driving transistor (230) connected to the red light-emitting unit (100), the driving current generated by the driving transistor (230) connected to the green light-emitting unit (100), and the driving current generated by the driving transistor (230) connected to the blue light-emitting unit (100) have a ratio a:b:c, satisfying that a:b:c is equal to the ratio between the red light flux, the green light flux, and the blue light flux corresponding to white light at the color coordinates corresponding to the display panel.

3. The pixel driving circuit according to claim 2, characterized in that: The bistable trigger (240) includes a third transistor (T1), a fourth transistor (T2), a fifth transistor (T3) and a sixth transistor (T4); The source of the third transistor (T1) and the source of the fifth transistor (T3) are both electrically connected to a first input port (201), the first input port (201) is connected to a third voltage, the drain of the third transistor (T1) and the drain of the fourth transistor (T2) are both electrically connected to the drain of the first transistor (210), the gate of the third transistor (T1) is electrically connected to the gate of the fourth transistor (T2), a first node (A) is provided on a connection line between the gate of the third transistor (T1) and the gate of the fourth transistor (T2), the source of the fourth transistor (T2) and the source of the sixth transistor (T4) are both electrically connected to a second input port (202), the second input port (202) is connected to the second voltage, and the source of the fourth transistor (T2) is also electrically connected to the source of the second transistor (220); The gate of the fifth transistor (T3) and the gate of the sixth transistor (T4) are both electrically connected to the drain of the first transistor (210), the drain of the fifth transistor (T3) is electrically connected to the drain of the sixth transistor (T4), a second node (B) is provided on a connection line between the drain of the fifth transistor (T3) and the drain of the sixth transistor (T4), the first node (A) is electrically connected to the second node (B), the second node (B) is electrically connected to an output port (241), and the output port (241) is electrically connected to the gate of the driving transistor (230).

4. The pixel driving circuit according to claim 3, characterized in that: The third transistor (T1), the fifth transistor (T3) and the driving transistor (230) are P-type transistors, and the first transistor (210), the second transistor (220), the fourth transistor (T2) and the sixth transistor (T4) are N-type transistors.

5. The pixel driving circuit according to claim 3, characterized in that: The source of the driving transistor (230) is electrically connected to the third input port (203), and the third input port (203) is configured to be electrically connected to the first power module (310) through a first signal line (301), and the first power module (310) is configured to provide the first voltage corresponding to the color of the light-emitting unit (100); The second input port (202) is configured to be electrically connected to a second power supply module (320) via a second signal line (302), and the second power supply module (320) is configured to provide the second voltage corresponding to the color of the light-emitting unit (100); The first signal line (301) corresponding to the red light-emitting unit (100), the first signal line (301) corresponding to the green light-emitting unit (100), and the first signal line (301) corresponding to the blue light-emitting unit (100) are arranged in different layers of the display panel; and / or the second signal line (302) corresponding to the red light-emitting unit (100), the second signal line (302) corresponding to the green light-emitting unit (100), and the second signal line (302) corresponding to the blue light-emitting unit (100) are arranged in different layers of the display panel.

6. The pixel driving circuit according to claim 1, characterized in that: When the driving transistor (230) operates in a saturation region, the first voltage, the second voltage and the driving current satisfy the following corresponding relationship: Among them, I ds is the driving current, μ is the mobility of the driving transistor (230), C ox is the capacitance per unit area of ​​the gate oxide layer of the driving transistor (230), W is the channel width of the driving transistor (230), L is the channel length of the driving transistor (230), V gs is the difference between the first voltage and the second voltage, V th is the threshold voltage of the driving transistor (230).

7. A pixel driving method, characterized in that: Used to drive the pixel driving circuit according to any one of claims 1 to 6, the method comprising: Based on the input row scanning signal, the first transistor (210) transmits the received light emitting data signal to the bistable trigger (240) when it is turned on; Based on the light emitting data signal, the bistable trigger (240) loads the received second voltage to the gate of the driving transistor (230) according to a set timing sequence, so as to turn on the driving transistor (230); The driving transistor (230) generates a driving current according to a first voltage received by a source and a second voltage received by a gate, wherein the first voltage and the second voltage both correspond to the color of the light-emitting unit (100); Based on the driving current and the conduction time of the driving transistor (230), the light emitting unit (100) is driven to emit light.

8. The pixel driving method according to claim 7, characterized in that: The color of the light-emitting unit (100) is any one of red, green and blue; The driving current received by the red light-emitting unit (100), the driving current received by the green light-emitting unit (100), and the driving current received by the blue light-emitting unit (100) have a ratio of a:b:c, satisfying that: a:b:c is equal to the ratio of the red light flux, the green light flux, and the blue light flux corresponding to the white light under the color coordinates corresponding to the display panel.

9. The pixel driving method according to claim 7, characterized in that: When the driving transistor (230) operates in a saturation region, the first voltage, the second voltage and the driving current satisfy the following corresponding relationship: Among them, I ds is the driving current, μ is the mobility of the driving transistor (230), C ox is the capacitance per unit area of ​​the gate oxide layer of the driving transistor (230), W is the channel width of the driving transistor (230), L is the channel length of the driving transistor (230), V gs is the difference between the first voltage and the second voltage, V th is the threshold voltage of the driving transistor (230).

10. A display panel, characterized in that: The method comprises the pixel driving circuit as claimed in any one of claims 1 to 6.

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