Constant-current driving circuit, driving chip and display device

Abstract

The invention discloses a constant-current driving circuit, a constant-current driving chip and a display device, which are applied to a display screen and comprise a constant-current module used for outputting current through a channel end; the detection module is used for receiving the sub-frame gray scale, detecting whether the sub-frame gray scale is 0 or not and outputting a detection signal indicating whether each sub-frame gray scale is 0 or not; and the pre-charging module is electrically connected with the detection module, and after judging that the gray scale of the current sub-frame is 0 based on the detection signal, the pre-charging module is in a closed state until the pre-charging state starts, and / or the pre-charging module is in a closed state after the pre-charging state and before judging whether the next sub-frame is 0 based on the detection signal. According to the constant current driving circuit, the constant current driving chip and the display device, the low power consumption requirement and the decoupling effect of the chip can be considered.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a constant current drive circuit, a drive chip and a display device. Background Art

[0002] Figure 1 The figure shows a common LED (Light Emitting Diode) display system. Multiple constant current driver chips are cascaded, and a single constant current driver chip is configured with multiple constant current output channels that are connected one-to-one with the column lines of the display. The row driver chip scans each row in sequence, and the constant current driver chip outputs constant current through the channel to light up the lamp beads.

[0003] Affected by parasitic capacitance coupling, the display system has many display problems such as dark first row, ghosting, high and low gray coupling and cross-board color difference. The mainstream solution is to configure a pre-charge function for the constant current driver chip to clamp the column line potential. Figure 2 The channel circuit structure of a constant current driver chip with a pre-charging function is shown. Taking a common anode display screen as an example, the channel circuit mainly includes: a pre-charging circuit and a constant current output circuit. The output ends of the two are electrically connected to form a channel end (OUT), and the channel end is connected to the display screen column line. Under the control of one or more pre-charging control signals, the pre-charging circuit can charge the channel end to different potentials to achieve decoupling and improve the display effect.

[0004] In the prior art, when the displayed data is 0, the pre-charging circuit has the following two conventional working modes: Mode 1: The pre-charging circuit is turned on at both the front and back ends of the line cycle. Since the display includes multiple cascaded constant current driver chips, each constant current driver chip includes multiple channels, and each channel is equipped with a pre-charging circuit, mode 1 is bound to increase system power consumption.

[0005] Mode 2: During the entire row cycle, the pre-charge circuit is directly turned off. This mode reduces power consumption at the expense of decoupling effect.

[0006] In view of this, how to strike a balance between display effect and power consumption is an issue that needs to be urgently addressed. Summary of the invention

[0007] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0008] In order to at least partially solve the above problem, according to a first aspect of the present invention, a constant current driving circuit is provided, which is applied to a display screen, comprising: A constant current module, used for outputting current through a channel end, wherein the channel end is a connection point between the constant current module and the pre-charging module; A detection module, used for receiving a subframe grayscale and detecting whether the subframe grayscale is 0, and outputting a detection signal; A pre-charging module, electrically connected to the detection module, after determining that the gray scale of the current subframe is 0 based on the detection signal, the pre-charging module is placed in a closed state until the pre-charging state begins, and / or the pre-charging module is placed in a closed state after the pre-charging state and before determining whether the next subframe is 0 based on the detection signal; The pre-charging state refers to the pre-charging module charging the channel end to the first voltage V1 and then switching to the second voltage V2.

[0009] Exemplarily, the detection module detects whether the grayscale of the subframe corresponding to the line break signal is 0 in response to the line break signal.

[0010] Exemplarily, the detection module detects whether the grayscale of the subframe corresponding to the current row is 0 before or after the line break signal of the current row.

[0011] Exemplarily, the start time and / or end time of the pre-charge state may be adjusted.

[0012] Exemplarily, the duration of the pre-charge state is adjustable.

[0013] Exemplarily, the display screen is a common anode display screen, and the first voltage is greater than the second voltage.

[0014] Exemplarily, the display screen is a common cathode display screen, and the first voltage is less than the second voltage.

[0015] According to a second aspect of the present application, a constant current driving circuit is provided, which is applied to a display screen, comprising: A constant current module, used to output current through a channel end, the channel end being a connection point between the constant current module and the pre-charging module; A detection module, used for receiving a subframe grayscale and detecting whether the subframe grayscale is 0; A pre-charging module, electrically connected to the detection module, and when the gray scale of the subframe corresponding to the next row is 0, the pre-charging module is placed in a closed state after the current row display ends or the pre-charging state ends; The pre-charging state refers to that the pre-charging module charges the channel end to the first voltage V1 and then switches to the second voltage V2.

[0016] According to a third aspect of the present invention, a constant current driving chip is provided, which includes the constant current driving circuit as described in the first aspect or the second aspect above.

[0017] According to a fourth aspect of the present invention, a display device is provided, comprising a display screen and the constant current driving chip as described in the third aspect above.

[0018] The constant current driving circuit, driving chip and display device provided by the present invention, after judging that the gray scale of the current subframe is 0 based on the detection signal, the pre-charging module is placed in a closed state until the pre-charging state begins, and / or the pre-charging module is placed in a closed state after the pre-charging state and before judging whether the next subframe is 0 based on the detection signal. According to the scheme of the present invention, the decoupling effect can be ensured while saving power consumption, thereby ensuring the display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following drawings of the present application are used as a part of the present application for understanding the present application. The drawings show the embodiments of the present application and their descriptions, which are used to explain the device and principle of the present application.

[0020] Figure 1 is a schematic diagram of a display screen system in the related art; Figure 2 Schematic diagram of a channel circuit of a constant current driving circuit according to an embodiment of the present application; Figure 3 is a schematic diagram of a display frame according to an embodiment of the present application; Figure 4 It is a schematic diagram of a pre-charging method in the related art; Figure 5 A schematic diagram of simulating the turning on of a lamp bead according to an embodiment of the present application; Figure 6 is a schematic diagram of a constant current driving circuit according to an embodiment of the present application; Figure 7 A schematic diagram of a pre-charging method according to an embodiment of the present application Figure 1 ; Figure 8 A schematic diagram of a pre-charging method according to an embodiment of the present application Figure 2 ; Fig. 9 A schematic diagram of a pre-charging method according to an embodiment of the present application Figure 3 ; Fig.10 A schematic diagram of a pre-charging method according to an embodiment of the present application Figure 4 ; Fig.11 A schematic diagram of a pre-charging method according to an embodiment of the present application Figure 5 ; Fig.12A schematic diagram of a pre-charging method according to an embodiment of the present application Figure 6 . DETAILED DESCRIPTION

[0021] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described.

[0022] It should be understood that the present application can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0023] It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish an element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part.

[0024] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used herein for convenience of description to describe the relationship of one element or feature to other elements or features shown in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation shown in the figures.

[0025] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0026] Embodiments of the invention are described herein with reference to cross-sectional views as schematic diagrams of ideal embodiments (and intermediate structures) of the present application. Thus, variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the present application should not be limited to the specific shapes shown herein, but include shape deviations due to, for example, manufacturing. Therefore, what is shown in the figures is schematic in nature, and their shapes are not intended to show the actual shapes of the device components and are not intended to limit the scope of the present application.

[0027] For ease of understanding, the terms such as channel terminal OUT, subframe grayscale, and pre-charge state in this application are briefly explained here.

[0028] Channel side: See also Figure 1 , Figure 2 , Figure 6 The pre-charging module is electrically connected to the constant current module, and the connection end is the channel end OUT mentioned in this application. Figure 1 The display screen column line connection shown in the figure. When displaying, the pre-charging module is turned off, the constant current module is turned on and outputs current through the channel terminal OUT to light up the lamp beads. When decoupling is required, the pre-charging module is turned on, the constant current module is in the off state, and the pre-charging module charges the column line through the channel terminal OUT. According to the predetermined pre-charging method, the column line potential is clamped to different potentials according to the timing.

[0029] Subframe grayscale: See also Figure 3 In order to improve the refresh rate, the mainstream display method divides a complete display frame into multiple subframes and displays them one by one. Taking m scan, n subframes, and progressive scanning as an example, the complete display order is: subframe 1 (R1-1) of the first row, subframe 1 (R2-1) of the second row, ..., subframe 1 (Rm-1) of the mth row, subframe 2 (R1-2) of the first row, subframe 2 (R2-2) of the second row, ..., subframe 2 (Rm-2) of the mth row, ..., subframe n (R1-n) of the first row, subframe n (R2-n) of the second row, ..., subframe n (Rm-n) of the mth row. Generally, when displaying, a period of time (row period) is allocated to each subframe (such as R1-1) for display. In the absence of compensation, the time allocated to each subframe is the same; in the case of compensation, the time allocated to some or all subframes may be different. Figure 4 It shows that the subframes are switched by the line feed signal. For example, the time corresponding to the first line feed signal is used to display the subframe R1-1, and the time corresponding to the second line feed signal is used to display R2-1.

[0030] The subframe grayscales described in this application are the grayscale values ​​corresponding to the aforementioned subframes R1-1, R2-1, ..., Rm-n, etc. The first row of subframes i to the mth row of subframes i constitute the grayscale values ​​of this application. Figure 3 A display group is shown, where i is an integer between 1 and n.

[0031] It should be noted that the brightness of the lamp bead is related to the total grayscale, and the total grayscale of the lamp bead is equal to the sum of the sub-frame grayscales. For example, the total grayscale of the first lamp bead in the first row is equal to the sum of the grayscales of R1-1, R1-2, ..., R1-n.

[0032] Pre-charge state: In this application, please see Figure 4-Figure 5 , Figure 7-Figure 12 , pre-charge 2-1 and pre-charge 2-2 constitute the pre-charge state, and there may be a pre-charge shutdown between the two. In pre-charge 2-1, the pre-charge module charges the column line potential to the first potential, and then, in pre-charge 2-2, the column line potential is clamped or switched to the second potential. The pre-charge state is used to solve the high contrast interference problem, which is the main display problem caused by parasitic capacitance on the display. For details, please refer to Figure 5 Taking the common anode display as an example, when the subframe grayscale is 0, the pre-charge module will be turned on (blue line), the column line potential will be charged to VR_1 (corresponding to pre-charge 2-1), and then clamped to VR_2 (corresponding to pre-charge 2-2) to simulate the lamp bead lighting process when the constant current source is turned on (black line), △Vr2≈△Vr1.

[0033] In order to facilitate those skilled in the art to accurately understand the concept of the present invention, the technical issues of the present application are explained below.

[0034] Please refer to Figure 1 The display screen system at least includes: a row driver chip, a constant current driver chip and an LED lamp bead array. Taking the common anode display screen as an example, the row driver chip includes a PMOS tube corresponding to each row line. According to the scanning signal, each row of PMOS tubes is turned on one by one to pull up the corresponding row line potential; the constant current driver chip is configured with multiple current output channels, each channel is connected to a column line to output a constant current. The row driver chip and the constant current driver chip cooperate with each other to light up the lamp beads row by row to achieve display. Specifically, taking row-by-row scanning as an example, the working principle of the display screen system is as follows: Step 1: The PMOS in row 1 is turned on, the PMOS in other rows are turned off, the row line in row 1 is connected to the power supply, and the row lines in other rows are high impedance; Step 2: The constant current driver chip enables the corresponding constant current output channel to output constant current according to the display data of the first row, lighting up the corresponding LED display beads in the first row.

[0035] Repeat steps 1 and 2 to display all the lines.

[0036] Due to the existence of parasitic capacitance, the actual display often has problems such as the first row being dark, ghosting, cross-board coupling, high and low gray coupling, etc. In order to reduce the impact on the display effect, the mainstream method is to configure a pre-charging circuit in each channel to clamp the column line potential and release the charge of the parasitic capacitance. However, in actual operation, when the display data corresponding to a row cycle (such as the grayscale value of subframe R1-1) is 0, that is, the lamp beads do not need to be lit, the traditional pre-charging scheme often adopts two modes: Mode 1: The pre-charging circuit is turned on at both the front and back ends of the line cycle. Since the display includes multiple cascaded constant current driver chips, each constant current driver chip includes multiple channels, and each channel is equipped with a pre-charging circuit, mode 1 will inevitably increase system power consumption.

[0037] Figure 4 This is a schematic diagram of the pre-charging method in the related art. The time between the front and rear line change signals is a line cycle. Under normal circumstances (without black field compensation), the time of each line cycle is the same. When the sub-frame grayscale is not 0, the pre-charging module is turned on at the front end of the line cycle to charge the column line to eliminate the dark first line (pre-charging 1); then, the pre-charging module is turned off, the constant current output channel is turned on, and the current output through the channel end lights up the lamp beads; at the end of the line cycle, the constant current output channel is turned off, and the pre-charging module is turned on to charge the column line again, so that when the next line is displayed, the ghost image is eliminated (pre-charging 3). When the sub-frame grayscale is 0, in addition to simulating the lamp beads to be turned on during the line cycle (pre-charging 2-1 and pre-charging 2-2), the pre-charging module will still be turned on at the front and back ends of the line cycle, retaining pre-charging 1 and pre-charging 3, and then charging the column lines.

[0038] Mode 2: During the entire row cycle, the pre-charge circuit is directly turned off. This mode reduces power consumption at the expense of decoupling effect.

[0039] Therefore, how to reasonably and scientifically control the state of the pre-charging circuit in the line cycle to take into account both the display effect and the low power consumption requirements has become a technical problem to be solved in this application.

[0040] See also Figure 5-Figure 6 In order to solve the above problems, the present application provides a constant current driving circuit, which is applied to a display screen. The circuit includes: a constant current module, a detection module and a pre-charging module.

[0041] A constant current module, used for outputting current through a channel terminal OUT, wherein the channel terminal OUT is a connection point between the constant current module and the pre-charging module; A detection module, used for receiving a subframe grayscale and detecting whether the subframe grayscale is 0, and outputting a detection signal; A pre-charging module is electrically connected to the detection module, and after determining that the gray scale of the current subframe is 0 based on the detection signal, the pre-charging module is placed in a closed state until the pre-charging state begins, and / or the pre-charging module is placed in a closed state after the pre-charging state and before determining whether the next subframe is 0 based on the detection signal; The pre-charging state refers to the pre-charging module charging the channel end to a first voltage V1 (pre-charging 2-1) and then switching to a second voltage V2 (pre-charging 2-2).

[0042] According to the implementation mode of the present application, it is detected whether the gray scale of each subframe is 0, and whether the gray scale of the subframe corresponding to the current row is 0 is used as a basis to determine the pre-charging process ( Figure 4 precharge 1) and / or the precharge process for blanking at the end of the row cycle ( Figure 4 Whether the pre-charging 3) is retained, and determine the shutdown timing and duration of the pre-charging module if the pre-charging process is not retained. Specifically, when the grayscale of the subframe corresponding to the current row is 0, the corresponding lamp bead is not lit, and the pre-charging module is turned off after the grayscale is determined to be 0 and continues until the simulated lamp bead is turned on (at the beginning of pre-charging 2-1), and / or, after the simulation of the lamp bead is turned on (at the end of pre-charging 2-2), the pre-charging module is turned off until the next detection of whether the grayscale of the next subframe is 0 (regardless of the result). According to this embodiment, on the one hand, the purpose of saving power consumption can be achieved, and on the other hand, since the simulation process of turning on the lamp bead is retained, the main problem caused by parasitic capacitance on the display effect, that is, the problem of high contrast interference, can be solved, and the purpose of decoupling is basically achieved. Therefore, the implementation method of the present application can take into account both low power consumption requirements and decoupling requirements.

[0043] In some implementations of this application, please see Figure 7-Figure 9 , a detection module, in response to a line break signal, detects whether the subframe grayscale corresponding to the line break signal is 0. Figure 7 , Figure 8 , Fig. 9 The situations where both the front-end pre-charge and the back-end pre-charge are not reserved, the front-end pre-charge is not reserved but the back-end pre-charge is reserved, and the back-end pre-charge is not reserved but the front-end pre-charge is reserved are respectively shown.

[0044] In this embodiment, when each line break signal arrives, the detection module detects whether the grayscale of the subframe corresponding to the line break signal is 0, and outputs the detection result. The system determines the working state of the pre-charging module based on the detection result, and when the grayscale is judged to be 0, the pre-charging module is turned off until the pre-charging state arrives, and or, after the pre-charging state ends, the pre-charging module is turned off, at least until the next subframe is detected.

[0045] Need to explain, Figure 8-Figure 9For example, in this application, if the front-end precharge (precharge 1) is retained, when the subframe grayscale is 0 or when the subframe grayscale is not 0, the corresponding front-end precharge voltage start time, end time, duration, and precharge voltage can be the same or different. Similarly, the back-end precharge (precharge 3) is also the same.

[0046] In some implementations of the present application, the line feed signal may be as follows: Figure 7-Figure 9 As shown, it is a pulse signal with a narrow pulse width. Of course, the line feed signal can also be a signal in other forms, which will not be described in detail in this application.

[0047] In some implementations of the present application, the detection module detects whether the grayscale of the subframe corresponding to the current row is 0 before or after the line break signal of the current row.

[0048] See also Fig.10 , the detection module detects whether the grayscale of the subframe to be displayed is 0 after the line break signal, and the pre-charging module adjusts the working state according to the detection result. In the present application, the detection of whether the subframe is 0 can be performed within a specified time after receiving the line break signal, such as within the first time (it should not be too far away from the line break signal to avoid affecting the display of the current line), that is, the detection time point of whether the subframe is 0 is not absolute for each subframe, but can be changed within a certain range after the line break according to actual needs. For example, when displaying subframe R3-1, the grayscale of R3-1 is detected a certain time after receiving the line break signal corresponding to R3-1.

[0049] See also Fig.11 , the detection module detects whether the grayscale of the subframe to be displayed is 0 before the line break signal, and the pre-charging module adjusts the working state according to the detection result. In the present application, the detection of whether the subframe is 0 can be performed within a specified time before the line break signal is received. For example, when displaying subframe R3-1, the grayscale of R3-1 is detected a certain time before the line break signal corresponding to R3-1 is received (actually within the display cycle corresponding to R2-1). Preferably, the detection is performed within the second time before the line break signal is received, and the second time needs to be as close to the line break signal as possible, outside the display area of ​​the previous line or outside the area where the pre-charging state is located, so as to avoid affecting the display or pre-charging state of the previous line.

[0050] In the present application, the detection of subframes can be performed one subframe at a time, for example, only one subframe is detected in one row period; or multiple subframes can be detected as a group, that is, the subframes are detected in batches, for example, m subframes corresponding to m rows are detected uniformly. In the case of early detection, the present application can generate a detection signal EN according to the detection result and a predetermined timing. For example, the detection signal EN is switched at a specified time after the line break signal, and the detection signal before the specified time indicates whether the previous subframe is 0, and the detection signal EN after the specified time indicates whether the current subframe is 0.

[0051] In some implementations of this application, in order to further reduce power consumption, only the simulation of the lamp bead turning on process is retained. Figure 10-11 As long as the grayscale of the subframe corresponding to the current row period is 0, the pre-charging process at the front end of the row period (eliminating the dark first row) and the pre-charging process at the back end (for the purpose of eliminating shadows) are omitted, and only the analog lamp bead turning-on process is retained. Since the high-contrast coupling problem is the main problem causing display problems, in this application, the analog lamp bead turning-on process that solves the main problem is retained to ensure that the display effect is not significantly affected and further achieve the purpose of energy saving.

[0052] According to a second aspect of the present application, another constant current driving circuit is provided, which is applied to a display screen, comprising: A constant current module, used to output current through a channel end, the channel end being a connection point between the constant current module and the pre-charging module; A detection module, used for receiving a subframe grayscale and detecting whether the subframe grayscale is 0; A pre-charging module is electrically connected to the detection module. When the gray scale of the subframe corresponding to the next row is 0, the pre-charging module is placed in a closed state after the current row display ends or the pre-charging state ends; The pre-charging state refers to the pre-charging module charging the channel end to the first voltage V1 and then switching to the second voltage V2.

[0053] See also Fig.12 Taking the subframe R2-1 corresponding to the current row (or row cycle) and the subframe R3-1 corresponding to the next row as an example, when the detection module determines that the grayscale of the subframe R3-1 of the next row is 0, the pre-charging module is turned off at the back end of the row cycle corresponding to the current row, that is, the pre-charging module is in the Floating state.

[0054] The main purpose of starting pre-charging to charge the column lines at the back end of the row cycle is to avoid ghosting when the next row is displayed. Since the grayscale of the next row subframe is 0, the lamp beads will not light up. Therefore, in order to save power consumption, the pre-charging module can be turned off at an appropriate time.

[0055] In some embodiments, for the constant current driving circuit provided in the second aspect, after detecting that the grayscale of the next row of subframes is 0, if the grayscale of the previous subframe is 0 (the grayscale of the subframe corresponding to the previous row), the pre-charging module is turned off after the pre-charging state corresponding to the previous subframe ends, and the closure is maintained at least until the row period corresponding to the previous subframe ends. Optionally, it can be maintained closed until the pre-charging 1 (if any) corresponding to the next subframe arrives, or until the pre-charging state (pre-charging 2-1 and pre-charging 2-2) corresponding to the next subframe arrives (if there is no pre-charging 1). If the grayscale of the previous subframe is not 0, after the display of the previous subframe ends (that is, after the constant current module is turned off), it is maintained closed at least until the row period corresponding to the previous subframe ends. Optionally, it can be maintained closed until the pre-charging 1 (if any) corresponding to the next subframe arrives, or until the pre-charging state (pre-charging 2-1 and pre-charging 2-2) corresponding to the next subframe arrives (if there is no pre-charging 1).

[0056] In some implementations, for the constant current driving circuit provided in the second aspect, when it is detected that the grayscale of the subframe corresponding to the current row is 0, the pre-charging module performs the operation of the constant current driving circuit provided in the first aspect. Please refer to the previous description and no further details will be given here.

[0057] In some embodiments, the display screen is a common anode display screen, and the first voltage V1 is greater than the second voltage V2. Figure 5 In the example, the VR_2 voltage must be much higher than the actual constant current start VR_5 voltage, otherwise, the lamp bead will be lit even if the subframe grayscale is 0.

[0058] In some implementations, the display screen is a common cathode display screen, and the first voltage V1 is less than the second voltage V2.

[0059] In some implementations, the start time and / or end time of the pre-charging state of the present application is adjustable and can be adjusted in real time according to the display effect.

[0060] In some implementations, the duration of the pre-charging state is adjustable and can be adjusted in real time according to the display effect.

[0061] In a third aspect, the present application proposes a constant current driving chip, which includes the constant current driving circuit described in the first aspect or the second aspect.

[0062] In a fourth aspect, the present application proposes a display device, which includes a display screen and the constant current driving chip described in the third aspect.

[0063] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0064] In the several embodiments provided in this application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0065] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0066] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0067] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstract and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0068] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0069] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims.

Claims

1. A constant current driving circuit, applied to a display screen, characterized in that: include: A constant current module, used for outputting current through a channel end, wherein the channel end is a connection point between the constant current module and the pre-charging module; A detection module, used for receiving a subframe grayscale and detecting whether the subframe grayscale is 0, and outputting a detection signal; A pre-charging module, electrically connected to the detection module, after determining that the gray scale of the current subframe is 0 based on the detection signal, the pre-charging module is placed in a closed state until the pre-charging state begins, and / or the pre-charging module is placed in a closed state after the pre-charging state and before determining whether the next subframe is 0 based on the detection signal; The pre-charging state refers to the pre-charging module charging the channel end to the first voltage V1 and then switching to the second voltage V2.

2. A constant current driving circuit according to claim 1, characterized in that: The detection module detects whether the grayscale of the subframe corresponding to the line break signal is 0 in response to the line break signal.

3. A constant current driving circuit according to claim 1, characterized in that: The detection module detects whether the grayscale of the subframe corresponding to the current row is 0 before or after the line break signal of the current row.

4. The constant current driving circuit according to any one of claims 1 to 3, characterized in that: The start time and / or end time of the pre-charging state can be adjusted.

5. The constant current driving circuit according to any one of claims 1 to 3, characterized in that: The duration of the pre-charge state is adjustable.

6. The constant current driving circuit according to any one of claims 1 to 3, characterized in that: The display screen is a common anode display screen, and the first voltage V1 is greater than the second voltage V2.

7. The constant current driving circuit according to any one of claims 1 to 3, characterized in that: The display screen is a common cathode display screen, and the first voltage V1 is less than the second voltage V2.

8. A constant current driving circuit, applied to a display screen, characterized in that: include: A constant current module, used for outputting current through a channel end, wherein the channel end is a connection point between the constant current module and the pre-charging module; A detection module, used for receiving a subframe grayscale and detecting whether the subframe grayscale is 0; A pre-charging module, electrically connected to the detection module, and when the gray scale of the subframe corresponding to the next row is 0, the pre-charging module is placed in a closed state after the current row display ends or the pre-charging state ends; The pre-charging state refers to the pre-charging module charging the channel end to the first voltage V1 and then switching to the second voltage V2.

9. A constant current driver chip, characterized in that: Comprising a constant current drive circuit as described in any one of claims 1-8.

10. A display device, characterized in that: include: A display screen and at least one constant current driving chip as claimed in claim 9.

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