Display panel, display device and dimming method

Abstract

The invention discloses a display panel, a display device and a dimming method. The display panel comprises a front-end system (10), a control unit (20), a driving chip (30) and a light-emitting unit. The light-emitting units comprise multiple light-emitting units, the multiple light-emitting units are the first light-emitting unit to the nth light-emitting unit, n is larger than 1, and each light-emitting unit emits light of different colors. The front-end system (10) is configured to emit a panel pulse modulation signal (LED-PWM). The control unit (20) receives a panel pulse modulation signal (LED-PWM), and generates a first pulse modulation signal (PWM1) to an nth pulse modulation signal (PWMn) according to the panel pulse modulation signal (LED-PWM). The driving chip (30) receives the kth pulse modulation signal and sends a kth driving signal to drive the kth light emitting unit according to the kth pulse modulation signal, and k is larger than or equal to 1 and smaller than or equal to n.

Description

Display panel, display device and dimming method TECHNICAL FIELD

[0001] The present application relates to the technical field of display, in particular to a display panel, a display device and a dimming method. BACKGROUND

[0002] High color gamut display products are more and more favored by consumers in the market, which is an important development direction in the display field. In order to meet the needs of users for high color gamut, a panel with multiple color light emitting unit chips can be used, for example, a BG Chip (blue-green light emitting unit) scheme, which can meet the requirements of low power consumption + high color gamut + ultra-thin + environmental protection at the same time.

[0003] However, the BG Chip light emitting unit chip uses different color light emitting units, and when the display brightness is reduced, the current driving the light emitting unit is also reduced. Due to the characteristics of different color light emitting units, some light emitting units will have color deviation problems, which will affect the display effect of the display panel. SUMMARY

[0004] The purpose of the present application is to provide a display panel, a display device and a dimming method which can improve color deviation.

[0005] The present application discloses a display panel, comprising:

[0006] A plurality of light emitting units, the plurality of light emitting units comprising a first light emitting unit to an n-th light emitting unit, each light emitting unit emitting light of a different color, n>1;

[0007] A front-end system configured to emit a panel pulse modulation signal;

[0008] A control unit configured to receive the panel pulse modulation signal and generate a first pulse modulation signal to an n-th pulse modulation signal according to the panel pulse modulation signal;

[0009] A plurality of driving chips comprising a first driving chip to an n-th driving chip, wherein the k-th driving chip is configured to receive the k-th pulse modulation signal and emit a k-th driving signal to drive the k-th light emitting unit according to the k-th pulse modulation signal, n>k>=1.

[0010] Optionally, the control unit is further configured to compare the panel pulse modulation signal with a first threshold value to determine the dimming mode of the display panel, and generate the first pulse modulation signal to the nth pulse modulation signal; wherein when the panel pulse modulation signal is greater than the first threshold value, the control unit sets the dimming mode of the display panel as direct current dimming; when the panel pulse modulation signal is less than or equal to the first threshold value, the control unit sets the dimming mode of the display panel as pulse width dimming.

[0011] Optionally, the display panel is further configured to set its dimming mode as direct current dimming when the luminance value of the light emitting unit is higher than a second threshold value; and set its dimming mode as pulse width dimming when the luminance value of the light emitting unit is lower than the second threshold value.

[0012] Optionally, in the direct current dimming mode, the kth driving chip is configured to adjust the size of the kth driving signal according to the kth pulse modulation signal; and in the pulse width dimming mode, the kth driving chip is configured to adjust the effective segment ratio of the kth driving signal according to the kth pulse modulation signal.

[0013] Optionally, the value of the kth driving signal generated by the kth driving chip in the pulse width dimming mode remains the maximum value of the kth driving signal generated by the kth driving chip in the direct current dimming mode.

[0014] Optionally, the control unit is further configured to receive the panel pulse modulation signal, and send the first pulse modulation signal to the nth pulse modulation signal according to a data preset table and the panel pulse modulation signal; the data preset table has the first pulse modulation signal to the nth pulse modulation signal corresponding to different panel pulse modulation signals under standard white.

[0015] Optionally, the n is 2, the first light emitting unit emits blue light, and the second light emitting unit emits green light; when the duty cycle of the panel pulse modulation signal is greater than a third threshold value, the duty cycles of the first pulse modulation signal and the second pulse modulation signal are equal; when the duty cycle of the panel pulse modulation signal is less than or equal to the third threshold value, the duty cycle of the first pulse modulation signal is greater than the duty cycle of the second pulse modulation signal.

[0016] Optionally, the third threshold value to 1% interval is divided into A interval and B interval from large to small in turn; when the panel pulse modulation signal is located in the A interval, the duty cycle ratio of the first pulse modulation signal and the second pulse modulation signal is (1-1.05):(0.95-1); when the panel pulse modulation signal is located in the B interval, the duty cycle ratio of the first pulse modulation signal and the second pulse modulation signal is (1.02-1.07):(0.9-0.95).

[0017] Optionally, the A interval is 45%-25%; the B interval is 25%-1%.

[0018] Optionally, the n is 2, the first kind of light emitting unit emits blue light, and the second kind of light emitting unit emits green light; when the luminance value of the light emitting unit is greater than the second threshold value, the duty cycle of the first pulse modulation signal and the second pulse modulation signal is equal; when the luminance value of the light emitting unit is less than the second threshold value, the duty cycle of the first pulse modulation signal is greater than the duty cycle of the second pulse modulation signal.

[0019] Optionally, the second threshold value to the minimum luminance value of the light emitting unit is divided into C interval and D interval from large to small in turn; when the luminance value of the light emitting unit is located in the C interval, the duty cycle ratio of the first pulse modulation signal and the second pulse modulation signal is (1-1.05):(0.95-1); when the luminance value of the light emitting unit is located in the D interval, the duty cycle ratio of the first pulse modulation signal and the second pulse modulation signal is (1.02-1.07):(0.9-0.95).

[0020] Optionally, the C interval is 45%-25% of the maximum luminance of the light emitting unit; the D interval is 25%-1% of the maximum luminance of the light emitting unit.

[0021] Optionally, the control unit is further configured to receive the panel pulse modulation signal, and emit the first pulse modulation signal to the n-th pulse modulation signal according to a data preset table and the panel pulse modulation signal; the data preset table is built-in with red, green and blue three color mapped gray scale data.

[0022] Optionally, in the data preset table, the green gray scale is output according to the original gray scale, the red gray scale is mapped to a lower gray scale than the green gray scale, and the blue gray scale is mapped to a lower gray scale than the green gray scale.

[0023] Optionally, the panel pulse modulation signal is divided into E interval, F interval and G interval from large to small in turn; when the panel pulse modulation signal is in the E interval and the F interval, the display panel is in a direct current dimming mode;

[0024] When the duty cycle of the panel pulse modulation signal is in the E interval, the red gray scale is initially reduced by one gray scale than the green gray scale, and in the E interval, the red gray scale is reduced by one gray scale more than the green gray scale for every 10% reduction in the duty cycle; the blue gray scale is initially reduced by two gray scales than the green gray scale, and in the E interval, the blue gray scale is reduced by two gray scales more than the green gray scale for every 10% reduction in the duty cycle;

[0025] When the duty cycle of the panel pulse modulation signal is in the F interval, the red gray scale is initially reduced by two gray scales than the green gray scale, and in the F interval, the red gray scale is reduced by two gray scales more than the green gray scale for every 10% reduction in the duty cycle; the blue gray scale is initially reduced by three gray scales than the green gray scale, and in the F interval, the blue gray scale is reduced by three gray scales more than the green gray scale for every 10% reduction in the duty cycle.

[0026] Optionally, the display panel is in a direct current dimming mode when the panel pulse modulation signal is in the G interval;

[0027] When the duty cycle of the panel pulse modulation signal is in the G interval, the red gray scale is initially reduced by ten gray scales than the green gray scale, and in the G interval, the red gray scale is reduced by ten gray scales more than the green gray scale for every 10% reduction in the duty cycle; the blue gray scale is initially reduced by fifteen gray scales than the green gray scale, and in the G interval, the blue gray scale is reduced by fifteen gray scales more than the green gray scale for every 10% reduction in the duty cycle.

[0028] Optionally, the display panel is in a pulse width dimming mode when the panel pulse modulation signal is in the G interval;

[0029] When the duty cycle of the panel pulse modulation signal is in the G interval, the red gray scale is mapped to a gray scale two levels lower than the green gray scale; the blue gray scale is mapped to a gray scale three levels lower than the green gray scale.

[0030] Optionally, the display panel comprises:

[0031] A display circuit board, the control unit and the driving chip are arranged on the display circuit board;

[0032] A light bar, the light bar comprises a light belt and a light emitting unit arranged on the light belt, the light belt is connected with the display circuit board and is configured to control the light emitting of the light emitting unit under the control of the signal of the display circuit board;

[0033] A light reflecting plate, a light guide plate and a second film layer structure, the light reflecting plate, the light guide plate and the second film layer structure are configured to make the light bar emit light uniformly.

[0034] Optionally, the display panel further includes:

[0035] A TFT substrate, which is connected to the display circuit board and configured to control the deflection of liquid crystal under the control of signals from the display circuit board;

[0036] The light emitted from the reflector, light guide plate, and second film layer structure passes through the color filter substrate and is converted into light of the corresponding color before being emitted.

[0037] Optionally, the number of light-emitting units is multiple, some of which are blue light-emitting units and others are green light-emitting units; an adjacent blue light-emitting unit and a green light-emitting unit form a group of light-emitting units, and the orthographic projection of the blue light-emitting unit in the thickness direction of the display panel overlaps with the green light-emitting unit in the group of light-emitting units.

[0038] Optionally, the number of light-emitting units is multiple, some of which are blue light-emitting units and others are green light-emitting units; an adjacent blue light-emitting unit and a green light-emitting unit form a group of light-emitting units, and the orthographic projection of the blue light-emitting unit in the length direction of the display panel overlaps with the green light-emitting unit in the group of light-emitting units.

[0039] Optionally, the k-th driver chip includes a data selector, a DC dimming module, a pulse width dimming module, and a driver module;

[0040] The driving module is connected to the light-emitting unit;

[0041] The DC dimming module is connected to the data selector and the drive module, and the pulse width dimming module is connected to the data selector and the drive module.

[0042] The data selector is configured to receive a panel pulse modulation signal or a k-th pulse modulation signal and output a selection signal to a DC dimming module or a pulse width dimming module.

[0043] The DC dimming module is configured to control the drive module to achieve DC dimming when it receives a selection signal;

[0044] The pulse width dimming module is configured to control the drive module to achieve pulse width dimming when it receives a selection signal.

[0045] Optionally, the DC dimming module includes:

[0046] A digital-to-analog converter, connected to the data selector, is configured to accept a selection signal and output a conversion signal;

[0047] The comparator has its positive terminal connected to the digital-to-analog converter, its negative terminal connected to the input terminal of the driver module, and its output terminal connected to the control terminal of the driver module.

[0048] Optionally, the pulse width modulation module includes:

[0049] A pulse width transistor (PWM) is provided, wherein the control terminal of the PWM transistor is connected to the data selector, the first terminal of the PWM transistor is grounded, and the second terminal of the PWM transistor is connected to the control terminal of the drive module.

[0050] Optionally, when the display panel is in pulse width dimming mode, the control electrode of the pulse width transistor receives the selection signal transmitted by the data selector and outputs a signal with high and low potentials periodically arranged to the control terminal of the drive module; the digital-to-analog converter receives the selection signal from the data selector and outputs a conversion signal, the comparator receives the conversion signal and outputs a stable reference signal to the control terminal of the drive module, and the drive module outputs a drive signal to the light-emitting unit.

[0051] Optionally, the driving module includes:

[0052] A driving transistor is provided, the control electrode of which is connected to the DC dimming module and the pulse width dimming module. The first electrode of the driving transistor is grounded through a first inductor, and the second electrode of the driving transistor is connected to the light-emitting unit.

[0053] This application also discloses a display device, which includes the display panel described above.

[0054] This application also discloses a dimming method, which is applied to the aforementioned display panel;

[0055] The method includes:

[0056] The front-end system emits a panel pulse modulation signal;

[0057] The control unit receives the panel pulse modulation signal and generates a first pulse modulation signal to an nth pulse modulation signal based on the panel pulse modulation signal.

[0058] The driver chip receives the k-th pulse modulation signal and issues the k-th driving signal according to the k-th pulse modulation signal to drive the k-th type of light-emitting unit, where n≥k≥1.

[0059] Compared with related technologies, this application sets up a control unit. The control unit receives the panel pulse modulation signal from the front-end system and sends first pulse modulation signals to the nth pulse modulation signal to the driver chip. The driver chip then sends first driving signals to the kth driving signal according to the first to nth pulse modulation signals, respectively, to drive the first to nth light-emitting units. This allows for the independent control of different types of light-emitting units, effectively preventing color shifts and other phenomena on the display panel when the driving current changes.

[0060] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this specification. Attached Figure Description

[0061] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this specification and, together with the description, serve to explain the principles of this specification.

[0062] Figure 1 is a schematic diagram of some modules of the display panel of this application.

[0063] Figure 2 is a schematic diagram of some modules of the display panel of this application.

[0064] Figure 3 is a flowchart of the operation of the display panel module of this application.

[0065] Figure 4 is a schematic diagram of a portion of the structure of the display panel in one embodiment of this application.

[0066] Figure 5 is a schematic diagram of the light strip and light-emitting unit in Figure 4 in one embodiment of this application.

[0067] Figure 6 is a schematic diagram of the light strip and light-emitting unit in Figure 4 in one embodiment of this application.

[0068] Figure 7 is a flowchart of the operation of the display panel module in one embodiment of this application.

[0069] Figure 8 is a comparison of the color shift of the display panel shown in Figure 7 before and after the improvement.

[0070] Figure 9 shows the relationship between the pulse modulation signal and the drive signal under the correlated pulse width dimming mode.

[0071] Figure 10 shows the relationship between the pulse modulation signal and the drive signal under the pulse width dimming mode of this application.

[0072] Figure 11 is a flowchart of the operation of the display panel module in one embodiment of this application.

[0073] Figure 12 is a flowchart of the operation of the display panel module in one embodiment of this application.

[0074] Figure 13 is a flowchart of the operation of the display panel module in one embodiment of this application.

[0075] Figure 14 is a flowchart of the operation of the display panel module in one embodiment of this application.

[0076] Figure 15 is a schematic diagram of the light strip and light-emitting unit in Figure 4 in one embodiment of this application.

[0077] Figure 16 is a schematic diagram of the hierarchical structure at the edge of the display panel in one embodiment of this application.

[0078] Figure 17 is a schematic diagram of the connection structure of the driver chip of the display panel in one embodiment of this application. Detailed Implementation

[0079] The technical solutions in the embodiments (or "implementations") of this application will be clearly and completely described herein with reference to the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0080] The terms "first" and "second" used in the embodiments of this application are for descriptive convenience only and should not be construed as indicating or implying relative importance.

[0081] In related technologies, the high color gamut solution in the display industry generally adopts a blue LED (Light Emitting Diode) + QD (Quantum Dot Conversion Film) conversion film. This solution has many drawbacks. For example, the blue LED + QD conversion film structure has a greater luminous efficiency loss than the ordinary white LED structure, which cannot meet the low power consumption requirements of display products. Furthermore, the QD film is thicker than ordinary films, making it incompatible with the ultra-thin film specifications required for achieving a high color gamut. Simultaneously, the QD film has a certain failure edge, where blue light emitted by the LED leaks out from the edge of the QD film, and the blue tinge around the QD film has become a persistent industry problem that urgently needs to be solved. Finally, most QD films in the industry are made of chromium-containing materials, which does not conform to the future trend of healthy displays, while chromium-free materials are extremely expensive, limiting the development of high color gamut technology. Based on this, a new multi-color light-emitting unit solution (such as the BG Chip solution) can simultaneously meet the requirements of low power consumption, high color gamut, ultra-thinness, and environmental friendliness. Because the driving current of different color light-emitting units increases or decreases proportionally, when the brightness of the display panel is reduced, i.e., the driving current decreases, some color light-emitting units will experience wavelength changes due to their own characteristics. This causes color shift in the light mixed from different color light-emitting units. For example, in a display panel with blue-green light-emitting units, when the driving current decreases, the green light-emitting unit, due to its own characteristics, will have a longer wavelength as the current decreases. This causes the displayed image to shift higher on the x-coordinate of the color coordinate system at low brightness, resulting in a reddish tint to the image.

[0082] As shown in Figures 1 and 3, in order to solve the above problems, this application provides a display panel, which includes a front-end system 10, a control unit 20, multiple driver chips 30 and a light-emitting unit.

[0083] The light-emitting unit includes multiple light-emitting units, which are the first type of light-emitting unit to the nth type of light-emitting unit, where n>1. Each type of light-emitting unit emits light of a different color. Specifically, the first type of light-emitting unit emits light of the first color, the second type of light-emitting unit emits light of the second color, and so on, until the nth type of light-emitting unit emits light of the nth color.

[0084] The front-end system 10 is configured to emit a panel pulse modulation signal LED-PWM.

[0085] The control unit 20 receives the panel pulse modulation signal LED-PWM and generates the first pulse modulation signal PWM1 to the nth pulse modulation signal PWMn based on the panel pulse modulation signal LED-PWM.

[0086] The plurality of driving chips 30 include a first driving chip to an nth driving chip, wherein the kth driving chip receives a kth pulse modulation signal and emits a kth driving signal to drive the kth type of light-emitting unit according to the kth pulse modulation signal, and n≥k≥1.

[0087] This application establishes a control unit that receives panel pulse modulation signals from the front-end system and sends first to nth pulse modulation signals to multiple driver chips. The first to nth driver chips then issue first to kth driving signals based on these signals, which are used to drive first to nth types of light-emitting units, respectively. This allows for the independent control of different types of light-emitting units, effectively preventing color shifts and other issues on the display panel when the driving current changes.

[0088] The following will provide a detailed description of various embodiments of this application that conform to the above-described inventive concept.

[0089] As shown in Figures 1 to 3, this application discloses a display panel, which is an LED display panel with multiple light-emitting units. For example, a display panel with blue-green light-emitting units, a display panel with blue-red light-emitting units, a display panel with green-red light-emitting units, or a display panel with red-blue-green light-emitting units, etc.

[0090] As shown in Figure 4, in this embodiment, a display panel with blue and green light-emitting units (BG Chips) is used as an example. The light-emitting units include a first type of light-emitting unit and a second type, wherein the first type of light-emitting unit is a blue light-emitting unit 41, and the second type is a green light-emitting unit 42. Both the blue light-emitting unit 41 and the green light-emitting unit 42 are disposed on the LED strip 40. The display panel mixes white light through the blue and green light-emitting units and the first film layer structure 43, then projects the mixed white light onto the entire back panel through the second film layer structure 44, and then converts the light into red, blue, and green light through structures such as the color conversion film 45, ultimately achieving a high color gamut display. The direction of the white light mixed by the blue light-emitting unit 41 and the green light-emitting unit 42 is not consistent with the light emission direction of the display panel. As shown in Figure 5, Figure 5 shows the structure of the LED strip 40 in Figure 4 in one embodiment. The blue light-emitting unit 41 and the green light-emitting unit 42 can be aligned and disposed on the LED strip 40. Specifically, an adjacent blue light-emitting unit 41 and a green light-emitting unit 42 form a group of light-emitting units. The orthographic projection of the blue light-emitting unit 41 along the thickness direction of the display panel overlaps with the green light-emitting unit 42 in this group. As shown in Figure 6, Figure 6 illustrates the structure of the light strip 40 in Figure 4 in one embodiment. The blue light-emitting unit 41 and the green light-emitting unit 42 can be staggered on the light strip 40. Specifically, an adjacent blue light-emitting unit 41 and a green light-emitting unit 42 form a group of light-emitting units. The orthographic projection of the blue light-emitting unit 41 along the thickness direction of the display panel partially overlaps with the green light-emitting unit 42 in this group. As shown in Figure 15, Figure 15 illustrates the structure of the light strip 40 in Figure 4 in one embodiment. The blue light-emitting unit 41 and the green light-emitting unit 42 can be spaced apart on the light strip 40. Specifically, an adjacent blue light-emitting unit 41 and a green light-emitting unit 42 form a group of light-emitting units. The orthographic projection of the blue light-emitting unit 41 along the length direction of the display panel overlaps with the green light-emitting unit 42 in this group. Of course, in other alternative embodiments, the blue light-emitting unit 41 and the green light-emitting unit 42 can be arranged according to the actual situation.

[0091] The display panel includes a front-end system 10, a control unit 20, a first driver chip 31, a second driver chip 32, and multiple light-emitting units. The front-end system 10 is connected to the control unit 20, which is simultaneously connected to both the first driver chip 31 and the second driver chip 32. The first driver chip 31 and the second driver chip 32 are respectively connected to the blue light-emitting unit and the green light-emitting unit. The connections described in this application refer to signal-transmitting connections. For example, when the front-end system 10 is connected to the control unit 20, the front-end system 10 can emit a panel pulse modulation signal (LED-PWM), which can be transmitted to the control unit 20.

[0092] During the operation of the display panel, the front-end system 10 sends a panel pulse modulation signal LED-PWM, which contains brightness information of the light-emitting units within the display panel. The control unit 20 receives the panel pulse modulation signal LED-PWM and sends a first pulse modulation signal PWM1 and a second pulse modulation signal PWM2 based on it. The first pulse modulation signal PWM1 contains brightness information of the blue light-emitting units within the display panel, and the second pulse modulation signal PWM2 contains brightness information of the green light-emitting units within the display panel. The first driver chip 31 receives the first pulse modulation signal PWM1 and sends a first drive signal OUT1 to drive the blue light-emitting unit; the first drive signal OUT1 is a current signal. The second driver chip 32 receives the second pulse modulation signal PWM2 and sends a second drive signal OUT2 to drive the green light-emitting unit; the second drive signal OUT2 is also a current signal. It can be understood that when the number of light-emitting units is greater than two, the number of signals sent by the control unit 20 and the number of driver chips 30 will also increase accordingly.

[0093] As shown in Figures 1 and 7, in an optional embodiment, the control unit 20 determines the magnitude of the panel pulse modulation signal LED-PWM. Specifically, the control unit 20 compares the panel pulse modulation signal LED-PWM with a first threshold a. When the panel pulse modulation signal LED-PWM is greater than the first threshold a, that is, when the ratio of the duty cycles of the effective potentials is greater than the first threshold a, the dimming mode of the display panel is adjusted to DC dimming (DC). When the panel pulse modulation signal LED-PWM is less than or equal to the first threshold a, that is, when the ratio of the duty cycles of the effective potentials is less than or equal to the first threshold a, the dimming mode of the display panel is adjusted to pulse width modulation (PWM). The first threshold a is the panel pulse modulation signal value when the panel begins to show color shift.

[0094] The driving current of different colored light-emitting units increases or decreases proportionally. When the brightness of the display panel is reduced, i.e., the duty cycle of the panel pulse modulation signal LED-PWM decreases, the driving current decreases. Due to their inherent characteristics, some colored light-emitting units will experience wavelength changes, leading to color shifts in the light mixed from different colored units. The first threshold 'a' corresponds to the magnitude of the current at which the light-emitting units experience wavelength changes due to their inherent characteristics. That is, in DC dimming mode, when the duty cycle decreases to the first threshold 'a', the light emitted by some colored light-emitting units will exhibit significant wavelength changes. Specifically, the value of the first threshold 'a' can be determined using the following method: In DC dimming mode, the panel pulse modulation signal LED-PWM is gradually reduced from its maximum value, and the light emitted by the display panel is detected. The reduction of the panel pulse modulation signal LED-PWM is stopped when the value of the displayed image on the color coordinates deviates from the preset value to the threshold. The value of the panel pulse modulation signal LED-PWM at this point is set as the first threshold 'a'. Thus, the minimum driving current of the light-emitting units is the driving current value of the panel pulse modulation signal LED-PWM in DC dimming mode when it is at the first threshold 'a'. In this case, the light emitted by the light-emitting unit of the display panel will not undergo significant wavelength changes, and the displayed image on the display panel will not deviate significantly in terms of color coordinates.

[0095] Taking a first threshold 'a' of 50% as an example, the front-end system 10 sends a panel pulse modulation signal LED-PWM. The control unit 20 receives the panel pulse modulation signal LED-PWM and determines the ratio of the duty cycles of the effective potentials contained in the panel pulse modulation signal LED-PWM. To prevent misjudgment, the control unit 20 can optionally determine the ratio of the duty cycles of the effective potentials contained in the panel pulse modulation signal LED-PWM across multiple frames. In this embodiment, the control unit 20 determines the ratio of the duty cycles of the effective potentials contained in the panel pulse modulation signal LED-PWM across three frames. When the duty cycle of the effective potential is determined to be greater than 50%, the control unit 20 outputs a command to set the display panel dimming mode to DC dimming, and outputs a first pulse modulation signal PWM1 and a second pulse modulation signal PWM2. The first driver chip 31 receives the first pulse modulation signal PWM1 and sends a first drive signal OUT1 to drive the blue light-emitting unit based on the first pulse modulation signal PWM1. The second driver chip 32 receives the second pulse modulation signal PWM2 and sends a second drive signal OUT2 to drive the green light-emitting unit based on the second pulse modulation signal PWM2. Of course, the value of 'a' needs to be determined based on the actual test value. In this embodiment, the value of 'a' is between 35% and 65%.

[0096] In an optional embodiment, the display panel is further configured to adjust its dimming mode based on the current brightness of the panel's light-emitting units. Specifically, when the brightness value of the light-emitting units is higher than a second threshold b, the display panel sets its dimming mode to DC dimming. When the brightness value of the light-emitting units is lower than the second threshold b, the display panel sets its dimming mode to pulse-width modulation (PWM). As shown in FIG4, the brightness value of the light-emitting units in this embodiment refers to the brightness of the white light mixed from the blue-green light-emitting units and the first film layer structure 43. Of course, in other display panels, the brightness value of the light-emitting units can be the brightness of light mixed from other light-emitting units. Specifically, in a display panel with a maximum brightness of 600 nits for the light-emitting units, when the current brightness of the light-emitting units is greater than 300 nits, the display panel uses DC dimming. When the current brightness of the light-emitting units is less than or equal to 300 nits, the display panel uses PWM dimming. In this embodiment, the second threshold b is located in the range of 35% to 65% of the maximum brightness value of the light-emitting units.

[0097] In DC dimming mode, both the first drive signal OUT1 and the second drive signal OUT2 are continuous current signals. The magnitudes of these current signals are related to the magnitudes of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2, respectively. In this embodiment, the magnitude of the first drive signal OUT1 is positively correlated with the magnitude of the first pulse modulation signal PWM1, and the magnitude of the second drive signal OUT2 is positively correlated with the magnitude of the second pulse modulation signal PWM2. Specifically, when the first pulse modulation signal PWM1 increases, and the ratio of the duty cycles of the effective potentials it contains increases (e.g., from 60% to 70%), the first drive signal OUT1 remains a continuous current signal, and the value of this current signal increases with the increase of the first pulse modulation signal PWM1. When the first pulse modulation signal PWM1 decreases, i.e., the ratio of the duty cycles of the effective potentials it contains decreases (e.g., from 70% to 60%), the first drive signal OUT1 remains a continuous current signal, and the value of this current signal decreases with the decrease of the first pulse modulation signal PWM1. The relationship between the second drive signal OUT2 and the second pulse modulation signal PWM2 is also the same, and will not be elaborated further here.

[0098] When the duty cycle of the effective potential is determined to be less than or equal to 50%, the control unit 20 outputs a command to set the display panel dimming mode to pulse width modulation (PWM), and outputs a first pulse modulation signal PWM1 and a second pulse modulation signal PWM2. The first driver chip 31 receives the first pulse modulation signal PWM1 and, based on PWM1, issues a first drive signal OUT1 to drive the blue light-emitting unit. The second driver chip 32 receives the second pulse modulation signal PWM2 and, based on PWM2, issues a second drive signal OUT2 to drive the green light-emitting unit.

[0099] In pulse width modulation (PWM) mode, both the first drive signal OUT1 and the second drive signal OUT2 output periodically interrupted current signals. These periodically interrupted current signals include periodically occurring active segments and inactive segments. In this embodiment, the active segment is the active current segment. During the active current segment, the first drive chip 31 and the second drive chip 32 output active current to the light-emitting unit, causing it to emit light. During the inactive segment, the first drive chip 31 and the second drive chip 32 do not output current to the light-emitting unit, and the light-emitting unit does not emit light. Furthermore, the proportion of the active current segment of this current signal is directly proportional to the magnitude of the panel pulse modulation signal LED-PWM. When the panel pulse modulation signal LED-PWM increases, i.e., when the ratio of the duty cycles of the active potentials it contains increases (for example, when the duty cycle increases from 30% to 40%), the first drive signal OUT1 and the second drive signal OUT2 remain periodically interrupted current signals, and the proportion of the active current segment of this current signal increases with the increase of the panel pulse modulation signal LED-PWM. When the panel pulse modulation signal LED-PWM decreases, meaning the duty cycle ratio of the effective potentials it contains decreases (e.g., from 40% to 30%), the first drive signal OUT1 and the second drive signal OUT2 remain periodically interrupted current signals, and the proportion of the effective current segment in these signals decreases as the panel pulse modulation signal LED-PWM decreases. Furthermore, in pulse width modulation mode, the magnitude of the effective current segment in the periodically interrupted current signal remains unchanged; only the proportion of the effective current segment within the cycle changes. Thus, in low-brightness conditions (LED-PWM less than 50%), the current received by the light-emitting unit does not decrease but becomes intermittent. The light-emitting unit will not experience wavelength changes due to the reduced current, thus preventing color shift problems on the display panel.

[0100] As shown in Figures 9 and 10, the horizontal axis in Figures 9 and 10 represents the LED-PWM panel pulse modulation signal, and the vertical axis represents the drive signal. The arrows under the horizontal axis point to the k-th pulse modulation signal. The pulse width modulation mode of this application differs from the pulse width modulation mode in Figure 9. Taking 'a' as 50% as an example, as shown in Figure 9, in the relevant pulse width modulation mode, after switching between DC dimming mode and pulse width modulation mode at the 50% duty cycle node of the panel, the current output to the light-emitting unit by the pulse width modulation mode remains the same as the current at 50% duty cycle in DC dimming mode. As shown in Figure 10, in the pulse width modulation mode of this application, after switching between DC dimming mode and pulse width modulation mode at the 50% duty cycle node of the panel, the current output to the light-emitting unit by the pulse width modulation mode remains the same as the current at 100% duty cycle in DC dimming mode, that is, it remains the maximum current value Imax in DC dimming mode. The duty cycle in the n-th pulse modulation signal of the pulse width modulation mode of this application is only half that of the relevant pulse width modulation mode. Thus, in the pulse-width dimming mode of this application, the current received by the light-emitting unit will remain at the same level as the current at 100% duty cycle in the DC dimming mode. Compared to the current at 50% duty cycle in the DC dimming mode, the wavelength of the light-emitting unit will change less, and the panel will experience less color shift. Of course, the current output to the light-emitting unit in the pulse-width dimming mode of this application can also be maintained at other values ​​greater than the current at duty cycle 'a' in the DC dimming mode. For example, taking 'a' as 50%, the current output to the light-emitting unit in the pulse-width dimming mode of this application can be maintained at the current value at duty cycles of 60%, 70%, 80%, 90%, or 95% in the DC dimming mode.

[0101] Figure 8 shows a comparison before and after color cast improvement. The dark line in the figure represents the x-coordinate offset before improvement, and the light line represents the x-coordinate offset after improvement. It can be clearly seen that the x-coordinate offset is significantly reduced after improvement.

[0102] As shown in Figures 1 and 11, in an optional embodiment, the control unit 20 receives the panel pulse modulation signal LED-PWM and sends the first pulse modulation signal to the nth pulse modulation signal according to the data preset table. As shown in Figures 2 and 12, in this embodiment, the control unit 20 receives the panel pulse modulation signal LED-PWM and sends the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 according to the data preset table.

[0103] As shown in Figures 2 and 13, in an optional embodiment, the data preset table contains a first pulse modulation signal PWM1 and a second pulse modulation signal PWM2 corresponding to different panel pulse modulation signals LED-PWM under standard white conditions. The control unit receives the panel pulse modulation signal LED-PWM and issues the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 according to the data preset table. The first driver chip 31 receives the first pulse modulation signal PWM1 and issues a first drive signal OUT1 to drive the blue light-emitting unit according to the first pulse modulation signal PWM1. The second driver chip 32 receives the second pulse modulation signal PWM2 and issues a second drive signal OUT2 to drive the green light-emitting unit according to the second pulse modulation signal PWM2.

[0104] In the preset data table, when the duty cycle of the panel pulse modulation signal LED-PWM is greater than the third threshold c, the duty cycles of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 are equal. When the duty cycle of the panel pulse modulation signal LED-PWM is less than or equal to the third threshold c, the duty cycle of the first pulse modulation signal PWM1 is greater than the duty cycle of the second pulse modulation signal PWM2. Specifically, when the duty cycle of the panel pulse modulation signal LED-PWM is less than or equal to the third threshold c, the duty cycle of the first pulse modulation signal PWM1 is greater than the duty cycle of the second pulse modulation signal PWM2. Specifically, the duty cycle of the first pulse modulation signal PWM1 is greater than the duty cycle of the panel pulse modulation signal LED-PWM, and the duty cycle of the second pulse modulation signal PWM2 is less than the duty cycle of the panel pulse modulation signal LED-PWM. The method for determining the value of the third threshold c is similar to that of the first threshold a, and will not be elaborated further here.

[0105] In an optional embodiment, the data preset table is shown in Table 1. The signal parameters in Table 1 are based on the color coordinates of standard white light in the color coordinate system, i.e., x = 0.313, y = 0.329. In Table 1, x represents the x-coordinate in the color coordinate system, y represents the y-coordinate in the color coordinate system, and Lv[cd / m 2 The symbol ] represents the brightness value. LED-PWM, PWM1 and PWM2 represent the panel pulse modulation signal LED-PWM, the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2, respectively.

[0106] In this embodiment, in the blue-green display panel, when the driving current decreases, the green light-emitting unit, due to its inherent characteristics, experiences a longer wavelength as the current decreases. This causes the displayed image to shift upwards in the x-coordinate of the color coordinate system at low brightness, resulting in a reddish tint. As indicated by the horseshoe-shaped color gamut curve, it is necessary to increase the G ratio (decreasing the x-coordinate and increasing the y-coordinate) and decrease the B ratio (decreasing the x-coordinate and increasing the y-coordinate) to simultaneously maintain the brightness without change before and after adjustment, while also calibrating the color coordinates back to the standard color coordinates.

[0107] Image quality is primarily determined by three factors: x-coordinate, y-coordinate, and Lv (light level). The reddish tint is mainly determined by the x-coordinate, followed by Lv. This is because a decrease of 0.001 in x results in an increase of 0.004 in y. Based on this principle, using the y-coordinate at 100% brightness as the standard, different B / G ratios are adjusted. This achieves image calibration, resulting in Table 1. For display panels containing other color emitting units, calibration can be performed based on the characteristics of each individual color emitting unit, leading to different data preset tables for different units.

[0108] Table 1 shows the signal parameters before calibration on the left and the signal parameters after calibration on the right. Before calibration, the duty cycle values ​​of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 are the same as the duty cycle value of the panel pulse modulation signal LED-PWM. After calibration, when the duty cycle of the panel pulse modulation signal LED-PWM is less than or equal to c, the duty cycle values ​​of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 are different from the duty cycle value of the panel pulse modulation signal LED-PWM. Of course, the calibration situation varies for different display panels. In other embodiments, the duty cycle values ​​of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 may be different from the duty cycle value of the panel pulse modulation signal LED-PWM when the duty cycle is greater than or equal to a certain value. Alternatively, the duty cycle values ​​of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 may be different from the duty cycle value of the panel pulse modulation signal LED-PWM when the duty cycle of the panel pulse modulation signal LED-PWM is within a certain interval or multiple intervals.

[0109] For example, the interval from the third threshold c to 1% is divided into interval A and interval B, from largest to smallest. When the duty cycle of the panel pulse modulation signal LED-PWM is in interval A, the duty cycle ratio of the first pulse modulation signal PWM1 to the second pulse modulation signal PWM2 is (1~1.05):(0.95~1). Optionally, the ratio of the first pulse modulation signal PWM1 can be 1.01, 1.015, 1.02, 1.025, or 1.05, etc. The ratio of the second pulse modulation signal PWM2 can be 0.95, 0.955, 0.97, 0.98, or 0.99, etc. When the duty cycle of the panel pulse modulation signal LED-PWM is in interval B, the duty cycle ratio of the first pulse modulation signal PWM1 to the second pulse modulation signal PWM2 is (1.02~1.07):(0.9~0.95). Optionally, the ratio of the first pulse modulation signal PWM1 can be 1.02, 1.025, 1.03, 1.044, or 1.07, etc. The ratio of the second pulse modulation signal PWM2 can be 0.90, 0.91, 0.916, 0.93, or 0.95, etc. In this embodiment, the third threshold c is 45%, interval A is 45% to 25%, and interval B is 25% to 1%, wherein 45% of the nodes belong to interval A and 25% of the nodes belong to interval B.

[0110] Specifically, in the data shown in Table 1, b = 45%. When the duty cycle of the panel pulse modulation signal LED-PWM is between 45% and 100%, the ratio of first pulse modulation signal PWM1: panel pulse modulation signal LED-PWM: second pulse modulation signal PWM2 = 1:1:1. When the duty cycle of the panel pulse modulation signal LED-PWM is between 25% and 45%, the ratio of first pulse modulation signal PWM1: panel pulse modulation signal LED-PWM: second pulse modulation signal PWM2 = 1.02:1:0.98. When the duty cycle of the panel pulse modulation signal LED-PWM is between 1% and 25%, the ratio of first pulse modulation signal PWM1: panel pulse modulation signal LED-PWM: second pulse modulation signal PWM2 = 1.044:1:0.916.

[0111] For example, when the duty cycle of the panel pulse modulation signal LED-PWM is 43%, the duty cycle of the first pulse modulation signal PWM1 is 43.8%, and the duty cycle of the second pulse modulation signal PWM2 is 42.1%. At this time, the coordinates of the displayed image on the color coordinate system are x = 0.3166, y = 0.3274, while the coordinates of the uncalibrated displayed image on the color coordinate system are x = 0.3176, y = 0.3233. As another example, when the duty cycle of the panel pulse modulation signal LED-PWM is 23%, the duty cycle of the first pulse modulation signal PWM1 is 24.012%, and the duty cycle of the second pulse modulation signal PWM2 is 21.068%. At this time, the coordinates of the displayed image on the color coordinate system are x = 0.3177, y = 0.3326, while the coordinates of the uncalibrated displayed image on the color coordinate system are x = 0.3224, y = 0.3161. The color coordinates of standard white are x = 0.313 and y = 0.329. It is evident that the calibrated image is closer to standard white. Furthermore, as shown in the table, the brightness of the display panel remains almost unchanged after calibration.

[0112] Table 1

[0113] In one optional embodiment, when the brightness value of the light-emitting unit is less than or equal to the second threshold b, the duty cycle values ​​of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 are different. Of course, the calibration conditions differ for different display panels. In other embodiments, the duty cycles of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 may be different when the brightness value of the light-emitting unit is greater than or equal to a certain value. Alternatively, the duty cycles of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 may be different when the brightness value of the light-emitting unit is within a certain range or multiple ranges.

[0114] In this embodiment, when the brightness value of the light-emitting unit is greater than the second threshold b, the duty cycles of the first pulse modulation signal PWM1 and the second pulse modulation signal PWM2 are equal. When the brightness value of the light-emitting unit is less than the second threshold b, the duty cycle of the first pulse modulation signal PWM1 is greater than the duty cycle of the second pulse modulation signal PWM2. Specifically, the range from the second threshold b to the minimum brightness value of the light-emitting unit is divided into interval C and interval D from largest to smallest. When the brightness value of the light-emitting unit is in interval C, the duty cycle ratio of the first pulse modulation signal PWM1 to the second pulse modulation signal PWM2 is (1~1.05):(0.95~1). Optionally, the ratio of the first pulse modulation signal PWM1 can be 1.01, 1.015, 1.02, 1.025, or 1.05, etc. The ratio of the second pulse modulation signal PWM2 can be 0.95, 0.955, 0.97, 0.98, or 0.99, etc. When the brightness value of the light-emitting unit is in the D range, the duty cycle ratio of the first pulse modulation signal PWM1 to the second pulse modulation signal PWM2 is (1.02~1.07):(0.9~0.95). Optionally, the ratio of the first pulse modulation signal PWM1 can be 1.02, 1.025, 1.03, 1.044, or 1.07, etc. The ratio of the second pulse modulation signal PWM2 can be 0.90, 0.91, 0.916, 0.93, or 0.95, etc. In this embodiment, the second threshold b is 45% of the maximum brightness of the light-emitting unit, the C range is 45%~25% of the maximum brightness of the light-emitting unit, and the D range is 25%~1% of the maximum brightness of the light-emitting unit, wherein the 45% node belongs to the C range and the 25% node belongs to the D range.

[0115] As shown in Figures 2 and 14, in an optional embodiment, the data preset table contains grayscale data mapped to red, green, and blue. The control unit 20 receives the panel pulse modulation signal LED-PWM and issues a first pulse modulation signal PWM1 and a second pulse modulation signal PWM2 according to the data preset table. Specifically, the control unit 20 receives the panel pulse modulation signal LED-PWM, detects the duty cycle value in the LED-PWM signal, and calls the data preset table corresponding to the duty cycle value. This data preset table contains calibrated red, green, and blue grayscale data for that duty cycle (i.e., that brightness). In this embodiment, in the data preset table, the green grayscale is output according to its original grayscale, the red grayscale is mapped to a grayscale lower than the green grayscale, and the blue grayscale is mapped to a grayscale lower than the green grayscale.

[0116] Taking a display panel with a maximum brightness of 600 nits as an example, the duty cycle data in the LED-PWM pulse modulation signal corresponds to different brightness levels of the display panel. During calibration, several brightness values ​​are first selected as binding points, i.e., several duty cycles are selected as binding points. In this embodiment, twenty binding points can be selected. All gray levels of each binding point are calibrated. Taking 256 gray levels for each brightness value as an example, the red, green, and blue gray levels of each gray level of the binding point are calibrated. Then, interpolation is performed between the binding points to obtain a preset data table for all brightness levels of the display panel.

[0117] The calibration of the binding points is based on the standard white light color coordinates x and y satisfying x = 0.313 and y = 0.329. Because the color point drift of the B / G lamp panel varies significantly under different brightness levels (i.e., different duty cycles), different R:G:B ratios need to be calibrated for different brightness levels. Therefore, this application selects several binding points, calibrates all gray levels within those binding points, and then obtains the calibrated data for the entire panel through interpolation, ultimately resulting in a preset data table containing gray level calibrations for all brightness values ​​of the display panel. In the preset data table, red is mapped to a gray level lower than the current gray level, green remains unchanged, and blue is mapped to a gray level lower than the current gray level. Of course, other mapping rules may exist in other panels, and the mapping may not necessarily follow this rule. The gray level calibration data aims to meet the actual color shift correction of the panel. This embodiment only uses a panel with blue-green emitting units as an example for illustration.

[0118] For example, in an optional embodiment, taking Table 2 as an example, when the front-end system 10 sends a panel pulse modulation signal LED-PWM, the control unit 20 receives the panel pulse modulation signal LED-PWM, detects the duty cycle value, and calls Table 2. Based on the calibrated data in Table 2, it outputs a first pulse modulation signal PWM1 and a second pulse modulation signal PWM2. Finally, the first driver chip 31 outputs a first drive signal OUT1 based on the first pulse modulation signal PWM1, and the second driver chip 32 outputs a second drive signal OUT2 based on the second pulse modulation signal PWM2, thereby controlling the display panel to emit calibrated light. The panel is in DC dimming mode when the panel pulse modulation signal LED-PWM corresponding to Table 2 is between 1% and 100%.

[0119] The panel pulse modulation signal (LED-PWM) is divided into three intervals from largest to smallest: E, F, and G. When the duty cycle of the LED-PWM signal is in the E interval, the red grayscale initially decreases by one grayscale level compared to the green grayscale. Furthermore, within the E interval, for every 10% decrease in duty cycle, the red grayscale decreases by one more grayscale level than the green grayscale. The blue grayscale initially decreases by two grayscale levels compared to the green grayscale. Similarly, within the E interval, for every 10% decrease in duty cycle, the blue grayscale decreases by two more grayscale levels than the green grayscale. When the panel pulse modulation signal (LED-PWM) duty cycle is in the F interval, the red grayscale initially decreases by two grayscale levels compared to the green grayscale. Furthermore, within the F interval, for every 10% decrease in duty cycle, the red grayscale decreases by two more grayscale levels than the green grayscale. The blue grayscale initially decreases by three grayscale levels compared to the green grayscale. Furthermore, within the F interval, for every 10% decrease in duty cycle, the blue grayscale decreases by three more grayscale levels than the green grayscale. When the duty cycle of the LED-PWM pulse modulation signal on the panel is in the G range, the red grayscale is initially ten grayscale levels lower than the green grayscale, and within the G range, for every 10% decrease in duty cycle, the red grayscale decreases by an additional ten grayscale levels compared to the green grayscale. The blue grayscale is initially fifteen grayscale levels lower than the green grayscale, and within the G range, for every 10% decrease in duty cycle, the blue grayscale decreases by an additional fifteen grayscale levels compared to the green grayscale.

[0120] In this embodiment, the E range is 100%-50%, the F range is 50%-25%, and the G range is 25%-1%, where 50% of the nodes belong to the F range and 25% of the nodes belong to the G range. Specifically, for example, when the duty cycle of the panel pulse modulation signal LED-PWM is 100%, the maximum grayscale value is 255, and the panel is standard white light, the red grayscale is 254, the green grayscale is 255, and the blue grayscale is 253. When the duty cycle of the panel pulse modulation signal LED-PWM is 45%, the maximum grayscale value is 255, and the panel is standard white light, the red grayscale is 253, the green grayscale is 255, and the blue grayscale is 252. When the duty cycle of the panel pulse modulation signal LED-PWM is 20%, the maximum grayscale value is 255, and the panel is standard white light, the red grayscale is 245, the green grayscale is 255, and the blue grayscale is 240.

[0121] Table 2

[0122] For example, in an optional embodiment, taking Table 3 as an example, the panel pulse modulation signal LED-PWM is divided into E interval, F interval, and G interval from large to small. When the panel pulse modulation signal LED-PWM is in the E interval or F interval, the display panel is in DC dimming mode, and when the panel pulse modulation signal LED-PWM is in the G interval, the display panel is in pulse width dimming mode.

[0123] When the duty cycle of the panel pulse modulation signal LED-PWM is in the E range, the red grayscale is initially one grayscale lower than the green grayscale, and within the E range, for every 10% decrease in duty cycle, the red grayscale is one grayscale lower than the green grayscale. The blue grayscale is initially two grayscale lower than the green grayscale, and within the E range, for every 10% decrease in duty cycle, the blue grayscale is two grayscale lower than the green grayscale. When the duty cycle of the panel pulse modulation signal LED-PWM is in the F range, the red grayscale is initially two grayscale lower than the green grayscale, and within the F range, for every 10% decrease in duty cycle, the red grayscale is two grayscale lower than the green grayscale. The blue grayscale is initially three grayscale lower than the green grayscale, and within the F range, for every 10% decrease in duty cycle, the blue grayscale is three grayscale lower than the green grayscale. When the duty cycle of the panel pulse modulation signal LED-PWM is in the G range, the red grayscale is mapped to a grayscale two levels lower than the green grayscale. The blue grayscale is mapped to a grayscale three levels lower than the green grayscale.

[0124] In this embodiment, the E range is 100%-50%, the F range is 50%-25%, and the G range is 25%-1%, where 50% of the nodes belong to the F range and 25% of the nodes belong to the G range. Specifically, for example, when the duty cycle of the panel pulse modulation signal LED-PWM is 100%, the maximum grayscale value is 255, and the panel is standard white light, the red grayscale is 254, the green grayscale is 255, and the blue grayscale is 253. When the duty cycle of the panel pulse modulation signal LED-PWM is 45%, the maximum grayscale value is 255, and the panel is standard white light, the red grayscale is 253, the green grayscale is 255, and the blue grayscale is 252. When the duty cycle of the panel pulse modulation signal LED-PWM is 20%, the maximum grayscale value is 255, and the panel is standard white light, the red grayscale is 253, the green grayscale is 255, and the blue grayscale is 252.

[0125] Table 3

[0126] As shown in Figure 16, in an optional embodiment, the display panel includes a display circuit board 100, a light strip 40, a reflector 200, a light guide plate 300, a second film layer structure 44, a lower polarizer 400, a TFT substrate 500, a color filter substrate 600, an upper polarizer 700, a back frame 800, and an adhesive 900.

[0127] A back frame 800 is disposed at the bottom of the display panel and bends upward at the edge of the display panel to protect it. Specifically, the back frame 800 includes a first frame segment 810, a second frame segment 820, and a third frame segment 830. The first frame segment 810 is horizontally disposed at the bottom of the display panel, horizontally covering the display panel, with its edge located at the edge of the display panel. The second frame segment 820 is located at the edge of the first frame segment 810 and extends upward from the edge of the first frame segment 810. The third frame segment 830 is located at the upper edge of the second frame segment 820 and extends inward from the upper edge of the second frame segment 820 into the display panel.

[0128] A light strip 40 is disposed at the edge of the display panel. Specifically, the light strip 40 is disposed on the upper side of the first frame segment 810 at the edge of the display panel and is attached to the first frame segment 810. The light strip 40 includes a light strip 402 and light-emitting units 401. The light strip 402 can be attached to the first frame segment 810, and a number of light-emitting units 401 are regularly arranged on the light strip 402. The light-emitting units 401 can be blue light-emitting units 41 or green light-emitting units 42, and their arrangement has been described in the above embodiments and will not be repeated here. A reflector 200 and a light guide plate 300 are disposed on the side of the light-emitting unit 401 near the inside of the display panel. The reflector 200 is disposed on the lower side of the light guide plate 300. The reflector 200 receives light from the light-emitting unit 401 and reflects it to the light guide plate 300. The light guide plate 300 reflects the light within the plate and guides it to further propagate to the entire display panel. The second film structure 44 is disposed on the upper side of the light guide plate 300. The second film structure 44 receives light from the light guide plate 300 and disperses the light more evenly to achieve a more uniform backlight effect. Optionally, the third frame segment 830 of the back frame 800 is located at the same horizontal height as the second film structure 44, and the third frame segment 830 is located on the upper side of the light-emitting unit 401 and the light guide plate 300.

[0129] Above the third frame segment 830 and the second film layer structure 44, a lower polarizer 400, a TFT substrate 500, a color filter substrate 600, and an upper polarizer 700 are sequentially arranged. The lower polarizer 400 and the upper polarizer 700 help filter out unwanted light, making the display panel clearer. The TFT substrate 500 has a circuit structure to control the deflection of the liquid crystal. The color filter substrate 600 has color filters corresponding to pixels, and red, green, and blue color filters can be arrayed on it. Light emitted from the reflector 200, light guide plate 300, and the second film layer structure 44 passes through the color filter substrate 600 and is converted into light of the corresponding color before being emitted.

[0130] As shown in Figures 16 and 17, the display circuit board 100 is disposed on the outer side of the second frame segment 820 of the back frame 800. The control unit 20 and multiple driver chips 30 are both disposed on the display circuit board 100. The display circuit board 100 is connected to the LED strip 402 and the TFT substrate 500. The display circuit board 100 outputs signals to the LED strip 402 to control the light emission of the light-emitting unit 401, and outputs signals to the TFT substrate 500 to control the deflection of the liquid crystal. Specifically, the driver chip 30 includes a data selector 33, a DC dimming module 34, a pulse width dimming module 35, and a driver module 36. The driver module 36 is connected to the light-emitting unit 401, the DC dimming module 34 is connected to the data selector 33 and the driver module 36, and the pulse width dimming module 35 is connected to the data selector 33 and the driver module 36. Optionally, the display panel may include a main control circuit board, on which the front-end system 10 is disposed. For example, the front-end system 10 may be a display module on the main control circuit board, which may also include a sound module or other modules. The front-end system 10 is connected to the control unit 20 via an eDP connector. The control unit 20 may be a TCON (Timing Controller) module or an MCU (Microcontroller Unit) disposed on the display circuit board 100. The control unit 20 is connected to the driver chip 30, which may be an integrated chip disposed on the display circuit board 100. The driver chip 30 may be connected to the LED strip 402 and the TFT substrate 500 via an FPC (Flexible Printed Circuit) to control the panel's light emission.

[0131] Data selector 33 is configured to receive the panel pulse modulation signal LED-PWM or the k-th pulse modulation signal PWMk and output a selection signal to the DC dimming module 34 or the pulse width dimming module 35. Optionally, data selector 33 can be a multiplexer (MUX). It is configured to receive the panel pulse modulation signal LED-PWM or the k-th pulse modulation signal PWMk, and selectively output a selection signal to the DC dimming module 34 or the pulse width dimming module 35 based on the determination information in the panel pulse modulation signal LED-PWM or the k-th pulse modulation signal PWMk. This determination information can be the duty cycle value of the panel pulse modulation signal LED-PWM or the k-th pulse modulation signal PWMk.

[0132] The DC dimming module 34 is configured to control the drive module 36 to achieve DC dimming when it receives a selection signal. The pulse width dimming module 35 is configured to control the drive module 36 to achieve pulse width dimming when it receives a selection signal.

[0133] As shown in Figure 17, in an optional embodiment, the DC dimming module 34 includes a digital-to-analog converter (DAC) 341 and a comparator 342. The DAC 341 is connected to a data selector 33 and is configured to accept a selection signal and output a conversion signal. The positive terminal of the comparator 342 is connected to the DAC 341, the negative terminal is connected to the input terminal of the drive module 36, and the output terminal is connected to the control terminal of the drive module 36. The comparator 342 is configured to receive the conversion signal output by the DAC and output a stable signal to the control terminal of the drive module 36, thereby achieving DC dimming.

[0134] The pulse width modulation (PWM) module 35 includes a pulse width transistor (PWM) T2. The control electrode of PWM T2 is connected to a data selector 33, the first electrode of PWM T2 is grounded, and the second electrode of PWM T2 is connected to the control terminal of the drive module 36. The control electrode of PWM T2 receives a selection signal transmitted from the data selector 33. This signal is a periodically arranged high and low potential signal. Under the control of this signal, PWM T2 also outputs a periodically arranged high and low potential signal to the control terminal of the drive module 36, thereby causing the drive module 36 to output intermittent drive signals. Simultaneously, the digital-to-analog converter (DAC) 341 receives the selection signal from the data selector 33 and outputs a conversion signal. The comparator 342 receives the conversion signal and outputs a stable reference signal to the control terminal of the drive module 36. This stable reference signal is used to determine the maximum value of the drive signal output by the drive module 36 in PWM dimming mode. In this embodiment, the maximum value is Imax. This achieves PWM dimming.

[0135] The driving module 36 includes a driving transistor T1. The control electrode of the driving transistor T1 is connected to the DC dimming module 34 and the pulse width dimming module 35. The first electrode of the driving transistor T1 is grounded through the first inductor L1, and the second electrode of the driving transistor T1 is connected to the light-emitting unit 401.

[0136] This application also discloses a display device, which includes the display panel described above.

[0137] This application also discloses a dimming method, which is applied to a display panel. The display panel includes a front-end system, a control unit, multiple driver chips, and multiple light-emitting units. The multiple light-emitting units include a first type of light-emitting unit to an nth type of light-emitting unit, and each light-emitting unit emits light of a different color.

[0138] The methods include:

[0139] The front-end system sends a panel pulse modulation signal;

[0140] The control unit receives the panel pulse modulation signal and generates the first pulse modulation signal to the nth pulse modulation signal based on the panel pulse modulation signal;

[0141] The k-th driver chip receives the k-th pulse modulation signal and sends out the k-th driving signal to drive the k-th type of light-emitting unit, where n≥k≥1.

[0142] It should be noted that the technical solutions or features described in the above embodiments can be combined or supplemented with each other without conflict. The scope of protection of this application is not limited to the precise structures described in the above embodiments and shown in the accompanying drawings; all modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

A display panel, characterized in that, The display panel comprises: a plurality of light emitting units, the plurality of light emitting units comprising a first light emitting unit to an nth light emitting unit, each light emitting unit emitting light of a different color, n>1; a front-end system configured to emit a panel pulse modulation signal; a control unit configured to receive the panel pulse modulation signal and generate a first pulse modulation signal to an nth pulse modulation signal according to the panel pulse modulation signal; a driving chip configured to receive a kth pulse modulation signal and emit a kth driving signal to drive a kth light emitting unit according to the kth pulse modulation signal, n≥k≥1. The display panel according to claim 1, characterized in that, The control unit is further configured to compare the panel pulse modulation signal with a first threshold value to determine a dimming mode of the display panel and generate the first pulse modulation signal to the nth pulse modulation signal; when the panel pulse modulation signal is greater than the first threshold value, the control unit sets the dimming mode of the display panel as direct current dimming; when the panel pulse modulation signal is less than or equal to the first threshold value, the control unit sets the dimming mode of the display panel as pulse width dimming. The display panel according to claim 1, characterized in that, The display panel is further configured to set its dimming mode as direct current dimming when the brightness value of the light emitting unit is higher than a second threshold value; and set its dimming mode as pulse width dimming when the brightness value of the light emitting unit is lower than the second threshold value. The display panel according to claim 2 or 3, characterized in that The number of driving chips is n, comprising a first driving chip to an nth driving chip, in the direct current dimming mode, the kth driving chip is configured to adjust the size of the kth driving signal according to the kth pulse modulation signal; In the pulse width dimming mode, the kth driving chip is configured to adjust the proportion of the effective segment of the kth driving signal according to the kth pulse modulation signal. The display panel according to claim 4, characterized in that, The value of the kth driving signal generated by the kth driving chip in the pulse width dimming mode remains the maximum value of the kth driving signal generated by the kth driving chip in the direct current dimming mode. The display panel according to claim 1, characterized in that, The control unit is further configured to receive the panel pulse modulation signal and emit the first pulse modulation signal to the nth pulse modulation signal according to a data preset table and the panel pulse modulation signal; the data preset table has the first pulse modulation signal to the nth pulse modulation signal corresponding to different panel pulse modulation signals under standard white. The display panel according to claim 1 or 6, characterized in that, The n is 2, the first light emitting unit emits blue light, and the second light emitting unit emits green light; when the duty cycle of the panel pulse modulation signal is greater than a third threshold value, the duty cycles of the first pulse modulation signal and the second pulse modulation signal are equal; when the duty cycle of the panel pulse modulation signal is less than or equal to the third threshold value, the duty cycle of the first pulse modulation signal is greater than the duty cycle of the second pulse modulation signal. The display panel according to claim 7, characterized in that, The third threshold value to 1% interval is divided into A interval and B interval from large to small in turn; when the panel pulse modulation signal is located in the A interval, the duty cycle ratio of the first pulse modulation signal and the second pulse modulation signal is (1-1.05):(0.95-1); when the panel pulse modulation signal is located in the B interval, the duty cycle ratio of the first pulse modulation signal and the second pulse modulation signal is (1.02-1.07):(0.9-0.95). The display panel according to claim 8, characterized in that, The A interval is 45%-25%; the B interval is 25%-1%. The display panel according to claim 1 or 6, characterized in that, The n is 2, the first light emitting unit emits blue light, and the second light emitting unit emits green light; when the luminance value of the light emitting unit is greater than a second threshold value, the duty cycle of the first pulse modulation signal and the second pulse modulation signal is equal; when the luminance value of the light emitting unit is less than the second threshold value, the duty cycle of the first pulse modulation signal is greater than that of the second pulse modulation signal. The display panel according to claim 10, characterized in that, The second threshold value to the minimum luminance value of the light emitting unit is divided into C interval and D interval from large to small in turn; when the luminance value of the light emitting unit is located in the C interval, the duty cycle ratio of the first pulse modulation signal and the second pulse modulation signal is (1-1.05):(0.95-1); when the luminance value of the light emitting unit is located in the D interval, the duty cycle ratio of the first pulse modulation signal and the second pulse modulation signal is (1.02-1.07):(0.9-0.95). The display panel according to claim 11, characterized in that, The C interval is 45%-25% of the maximum luminance of the light emitting unit; the D interval is 25%-1% of the maximum luminance of the light emitting unit. The display panel according to claim 1, characterized in that, The control unit is further configured to receive the panel pulse modulation signal, and emit the first pulse modulation signal to the n-th pulse modulation signal according to a data preset table and the panel pulse modulation signal; the data preset table is built-in with red, green and blue three-color mapped gray scale data. The display panel according to claim 13, characterized in that, In the data preset table, the green gray scale is output according to the original gray scale, the red gray scale is mapped to a lower gray scale than the green gray scale, and the blue gray scale is mapped to a lower gray scale than the green gray scale. The display panel according to any one of claims 1, 13 or 14, characterized in that The panel pulse modulation signal is divided into E interval, F interval and G interval from large to small in turn; the display panel is in a direct current dimming mode when the panel pulse modulation signal is in the E interval and the F interval; When the duty cycle of the panel pulse modulation signal is in the E interval, the red gray scale is initially reduced by one gray scale than the green gray scale, and in the E interval, the red gray scale is reduced by one gray scale more than the green gray scale for every 10% reduction of the duty cycle; The blue gray scale is initially reduced by two gray scales than the green gray scale, and in the E interval, the blue gray scale is reduced by two gray scales more than the green gray scale for every 10% reduction of the duty cycle; When the duty cycle of the panel pulse modulation signal is in the F interval, the red gray scale is initially reduced by two gray scales than the green gray scale, and in the F interval, the red gray scale is reduced by two gray scales more than the green gray scale for every 10% reduction of the duty cycle; The blue gray scale is initially reduced by three gray scales than the green gray scale, and the blue gray scale is reduced by three gray scales more than the green gray scale in each 10% duty cycle reduction in the G interval. The display panel according to claim 15, characterized in that, The display panel is in direct-current dimming mode when the panel pulse modulation signal is in the G interval; When the duty cycle of the panel pulse modulation signal is in the G interval, the red gray scale is initially reduced by ten gray scales than the green gray scale, and the red gray scale is reduced by ten gray scales more than the green gray scale in each 10% duty cycle reduction in the G interval; The blue gray scale is initially reduced by fifteen gray scales than the green gray scale, and the blue gray scale is reduced by fifteen gray scales more than the green gray scale in each 10% duty cycle reduction in the G interval. The display panel according to claim 15, characterized in that, The display panel is in pulse width dimming mode when the panel pulse modulation signal is in the G interval; When the duty cycle of the panel pulse modulation signal is in the G interval, the red gray scale is mapped to a gray scale two levels lower than the green gray scale; The blue gray scale is mapped to a gray scale three levels lower than the green gray scale. The display panel according to claim 1, characterized in that, The display panel comprises: A display circuit board, the control unit and the driving chip are arranged on the display circuit board; A light bar, the light bar comprises a light belt and a light emitting unit arranged on the light belt, the light belt is connected with the display circuit board and is configured to control the light emitting unit to emit light under the control of the signal of the display circuit board; A light reflecting plate, a light guide plate and a second film layer structure, the light reflecting plate, the light guide plate and the second film layer structure are configured to make the display panel emit light uniformly. The display panel of claim 18, wherein The number of light emitting units is multiple, part of which is blue light emitting unit and the other part is green light emitting unit; one blue light emitting unit and one green light emitting unit adjacent to each other form a group of light emitting units, and the orthogonal projection of the blue light emitting unit in the group of light emitting units on the thickness direction of the display panel overlaps with the green light emitting unit. The display panel of claim 18, wherein The number of light emitting units is multiple, part of which is blue light emitting unit and the other part is green light emitting unit; one blue light emitting unit and one green light emitting unit adjacent to each other form a group of light emitting units, and the orthogonal projection of the blue light emitting unit in the group of light emitting units on the length direction of the display panel overlaps with the green light emitting unit. The display panel of claim 18, wherein The kth driving chip comprises a data selector, a direct-current dimming module, a pulse width dimming module and a driving module; The driving module is connected with the light emitting unit; The direct-current dimming module is connected with the data selector and the driving module, and the pulse width dimming module is connected with the data selector and the driving module; The data selector is configured to receive the panel pulse modulation signal or the kth pulse modulation signal and output a selection signal to the direct-current dimming module or the pulse width dimming module; The direct-current dimming module is configured to regulate and control the driving module to realize direct-current dimming when it receives the selection signal; The pulse width dimming module is configured to regulate and control the driving module to realize pulse width dimming when it receives the selection signal. The display panel of claim 21, wherein The direct-current dimming module comprises: A digital-to-analog converter connected with the data selector and configured to accept the selection signal and output a conversion signal; A comparator, a positive terminal of the comparator being connected with the digital-to-analog converter, a negative terminal of the comparator being connected with the input terminal of the driving module, and an output terminal of the comparator being connected with the control terminal of the driving module. The display panel of claim 22, wherein The pulse width dimming module comprises: A pulse width transistor, a control terminal of the pulse width transistor being connected with the data selector, a first terminal of the pulse width transistor being grounded, and a second terminal of the pulse width transistor being connected with the control terminal of the driving module. The display panel according to claim 23, characterized in that, When the display panel is in the pulse width dimming mode, the control terminal of the pulse width transistor receives the selection signal transmitted by the data selector, and outputs a signal with high and low voltage periods arranged to the control terminal of the driving module. The digital-to-analog converter receives the selection signal from the data selector and outputs a conversion signal, the comparator receives the conversion signal and outputs a stable reference signal to the control terminal of the driving module, and the driving module outputs a driving signal to the light emitting unit. The display panel of claim 21, wherein The driving module comprises: A driving transistor, a control terminal of the driving transistor being connected with the direct current dimming module and the pulse width dimming module, a first terminal of the driving transistor being grounded through a first inductor, and a second terminal of the driving transistor being connected with the light emitting unit. A display device characterized by comprising: The display device comprises the display panel according to any one of claims 1-25. A dimming method, characterized in that, The method is applied to the display panel according to any one of claims 1-25. The method comprises: The front-end system sends a panel pulse modulation signal; The control unit receives the panel pulse modulation signal, and generates a first pulse modulation signal to an n-th pulse modulation signal according to the panel pulse modulation signal; The driving chip receives a k-th pulse modulation signal, and sends a k-th driving signal to drive a k-th kind of light emitting unit according to the k-th pulse modulation signal, n≥k≥1.

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