LED driving self-correcting circuit and method, column driving chip and display equipment

Abstract

The invention provides an LED driving self-correction circuit, a column driving chip and a display device, and the LED driving self-correction circuit comprises a reference voltage obtaining circuit which is used for obtaining the correction reference voltage of the column driving chip according to the average forward conduction voltage of a plurality of LED lamp beads connected with the column driving chip; the error acquisition circuit is used for acquiring an error of the correction reference voltage relative to the reference voltage; and the error self-correction circuit is used for carrying out addition processing on the pre-charging voltage and the corresponding error to obtain a target pre-charging voltage of the column driving chip so as to realize correction of the pre-charging voltage of the column driving chip. Through self-correction of the pre-charging voltage, the pre-charging voltage output to the LED display screen by each column of driving chips after correction is consistent, and the influence of color blocks on the display screen is effectively eliminated.

Description

Technical Field

[0001] The present application relates to the technical field of LED display driving, and in particular to an LED driving self-correction circuit, a column driving chip and a display device. Background Art

[0002] The LED display screen is composed of a light-emitting diode display array, row driver, column driver, etc. Figure 1 The display device 100 is a display device 100 having a common cathode (i.e., the cathodes of the LED lamp beads D11 to Dmn located in the same row are connected together, and the anodes are separated, and m and n are both integers greater than 1) connected LED display screen unit board 130 (hereinafter referred to as LED display screen or display screen) of course, the LED display screen 130 can also be a common anode (i.e., the anodes of the LED lamp beads D11 to Dmn located in the same row are connected together, and the cathodes are separated). Figure 1 All LED lamp beads D11~Dmn in the LED display screen 130 are reversed. Among them, the row driver chip 110 of the LED display screen 130 usually includes multiple switch power tubes Q11~Q1m, and the column driver chip 120 usually includes multiple constant current source driver chips. Usually, the constant current source driver chip will include multiple output channels, and the multiple output channels are connected Figure 1 The plurality of column driving lines (the 1st column, the 2nd column, ... the nth column) are connected and disconnected by a plurality of switch tubes Q21~Q2n.

[0003] In theory, the characteristics of the LED lamp beads used in the same LED display screen are the same, that is, the forward conduction voltage of each LED lamp bead D11~Dmn is the same. Therefore, when the pre-charge voltage Vpre output by each column driver chip to the LED lamp bead is the same, the same type of LED lamp bead can be guaranteed to have the same luminous brightness. However, even if the driver chip has been strictly adjusted before leaving the factory, it cannot be guaranteed that the pre-charge voltage output by each column driver chip soldered to the display light board is the same. If there is a difference in the pre-charge voltage output by each column driver chip to the LED lamp bead, the display effect of the display screen will be unsatisfactory, such as the appearance of color blocks. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides an LED driving self-correction circuit, a column driving chip and a display device, which can self-correct the pre-charging voltage so that after correction, the pre-charging voltage output by each column driving chip to the LED display screen is consistent, thereby eliminating the influence of color blocks on the display screen.

[0005] According to a first aspect of the present application, there is provided an LED driving self-correction circuit for self-correcting a pre-charge voltage pre-charged from a column driving chip to an LED lamp bead, the LED driving self-correction circuit comprising: A reference voltage acquisition circuit, used for obtaining a correction reference voltage of the column driver chip according to an average forward conduction voltage of a plurality of LED lamp beads connected to the column driver chip; An error acquisition circuit, used for acquiring an error of the correction reference voltage relative to a reference voltage; The error self-correction circuit is used to perform an addition process on the pre-charge voltage and the error to obtain a target pre-charge voltage of the column driver chip and realize correction of the pre-charge voltage.

[0006] Optionally, the reference voltage is a calibration reference voltage of any column driver chip.

[0007] Optionally, the correction reference voltage and the error are both digital signals.

[0008] Optionally, the reference voltage acquisition circuit is configured as: The forward conduction voltages of the plurality of LED lamp beads are collected in sequence, and the forward conduction voltages of the plurality of LED lamp beads are averaged to obtain the correction reference voltage.

[0009] Optionally, the LED driving self-correction circuit includes a plurality of sampling capacitors respectively connected in parallel with the plurality of LED lamp beads;

[0010] The reference voltage acquisition circuit is configured as follows:

[0011] Taking rows as units, after collecting the forward conduction voltage of each row of LED lamp beads based on the multiple sampling capacitors in each row, the multiple sampling capacitors in each row are controlled to be connected in parallel to obtain the average conduction voltage of each row of LED lamp beads, and the average conduction voltages of multiple rows of LED lamp beads are averaged to obtain the correction reference voltage.

[0012] Optionally, the reference voltage acquisition circuit includes: The analog-to-digital converter is used to collect the forward conduction voltage of the LED lamp bead when the LED lamp bead is lit, and quantize it into a corresponding digital signal; A memory, used to store a digital signal of the forward conduction voltage of the LED lamp bead; The processing unit is used to average the stored digital signals of the forward conduction voltages of the plurality of LED lamp beads to obtain the correction reference voltage.

[0013] Optionally, the reference voltage acquisition circuit includes: A plurality of first switches are respectively connected between the plurality of LED lamp beads and the plurality of sampling capacitors, and the plurality of first switches are controlled by a first control signal and are in a closed state in a first time period during which the row driving signal of the corresponding row is effective, so as to connect the plurality of sampling capacitors of the corresponding row to the collection channel of the forward conduction voltage of the plurality of LED lamp beads; A plurality of second switches are respectively connected between the first node and the plurality of sampling capacitors, the plurality of second switches are controlled by a second control signal and are in a closed state during a second time period when the row driving signal of the corresponding row is valid, so as to control the plurality of sampling capacitors of the corresponding row to be in a parallel state; An analog-to-digital converter, whose input terminal is connected to the first node, is used to quantize the average conduction voltage of each row of LED lamp beads into a corresponding digital signal; A memory, used to store a digital signal of the average conduction voltage of each row of LED lamp beads; The processing unit is used to average the digital signals of the average conduction voltages of the stored multiple rows of LED lamp beads to obtain the correction reference voltage.

[0014] Optionally, the error self-correction circuit includes: A digital-to-analog converter, wherein a first input terminal receives a digital error signal and a second input terminal receives a reference signal, wherein the digital-to-analog converter is used to convert the digital error signal into an analog error signal, wherein the digital error signal is a digital signal representation of the error; An adder, wherein a first input terminal receives the pre-charge voltage, a second input terminal receives the analog error signal, and an output terminal outputs the target pre-charge voltage.

[0015] Optionally, the error self-correction circuit includes: A scaling unit, wherein a first input terminal receives a digital error signal and a second input terminal receives a scaling factor, wherein the scaling unit is used to scale the digital error signal according to the scaling factor to obtain a scaled signal of the digital error signal, wherein the digital error signal is a digital signal representation of the error; A digital adder, having a first input terminal receiving the scaling signal, a second input terminal receiving a digital trimming signal, and an output terminal outputting a digital correction signal, wherein the digital trimming signal represents an error term of the column driver chip; A digital-to-analog converter receives the digital correction signal at its input end, and is used to convert the digital correction signal into an analog correction signal and output the analog correction signal to the precharge voltage output node of the column driver chip to obtain the target precharge voltage.

[0016] According to a second aspect of the present application, a LED driving self-calibration method is provided, comprising: Obtaining a calibration reference voltage of the column driver chip according to an average forward conduction voltage of a plurality of LED lamp beads connected to the column driver chip; Obtaining an error of a calibration reference voltage of the column driver chip relative to a reference voltage; The pre-charge voltage is added to the error to obtain a target pre-charge voltage of the column driver chip, thereby correcting the pre-charge voltage of the column driver chip.

[0017] Optionally, the reference voltage is a calibration reference voltage of any column driver chip.

[0018] Optionally, obtaining a correction reference voltage of the column driver chip according to an average forward conduction voltage of a plurality of LED lamp beads connected to the column driver chip comprises: Collecting the forward conduction voltage of each LED lamp bead in the plurality of LED lamp beads one by one; The forward conduction voltages of the plurality of LED lamp beads are averaged to obtain the correction reference voltage.

[0019] Optionally, obtaining a correction reference voltage of the column driver chip according to an average forward conduction voltage of a plurality of LED lamp beads connected to the column driver chip comprises: Based on a plurality of sampling capacitors connected in parallel to the plurality of LED lamp beads, the forward conduction voltage of each row of LED lamp beads is collected row by row; Controlling the plurality of sampling capacitors in each row to be connected in parallel to obtain an average conduction voltage of each row of LED lamp beads; The average conduction voltages of the multiple rows of LED lamp beads are averaged to obtain the correction reference voltage.

[0020] According to a third aspect of the present application, a column driver chip is provided, comprising: an LED driver self-correction circuit as described in any embodiment of the present application.

[0021] According to a fourth aspect of the present application, a display device is provided, comprising: at least one column driver chip as described in any embodiment of the present application.

[0022] Optionally, when the number of the column driver chips is 2 or more, the display device further includes: The control card is connected to each column driver chip respectively, receives a calibration reference voltage output by one of the column driver chips, and sends the received calibration reference voltage to each column driver chip to serve as a reference voltage of each column driver chip.

[0023] Optionally, when the number of the column driver chips is 2 or more, the 2 or more column driver chips transmit the calibration reference voltage output by one of the column driver chips to each column driver chip respectively through cascade transmission to serve as the reference voltage of each column driver chip.

[0024] The beneficial effects of this application include at least: The LED driver self-correction scheme disclosed in the embodiment of the present application obtains the correction reference voltage of the column driver chip according to the average forward conduction voltage of multiple LED lamp beads connected to the column driver chip (for example, the average forward conduction voltage of multiple LED lamp beads connected to the column driver chip is used as the correction reference voltage of the column driver chip), so that after the column driver chip is welded to the display light board, the obtained correction reference voltage of the column driver chip can still be used to self-correct the pre-charge voltage output by the column driver chip, that is, by calculating the error of the correction reference voltage of the column driver chip relative to the reference voltage (such as the correction reference voltage of any selected column driver chip), and adding the original pre-charge voltage output by the column driver chip to the error as the target pre-charge voltage of the column driver chip for the final pre-charge to the LED lamp beads, the final pre-charge voltage output by each column driver chip to the LED display screen can be made consistent, effectively eliminating the color blocks on the display screen and avoiding the influence of high temperature on chip output parameters during chip welding.

[0025] It should be noted that the above general description and the following detailed description are merely exemplary and explanatory and do not limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic structural diagram of a display device is shown; Figure 2 Show Figure 1 A schematic diagram of the timing sequence of some driving signals in a display device; Figure 3 Show Figure 1 A timing diagram of an actual pre-charge voltage in a display device; Figure 4 A schematic diagram showing the structure of a display device provided according to an embodiment of the present application is shown; Figure 5 Show Figure 4 A schematic diagram of an implementation of a reference voltage acquisition circuit in a display device; Figure 6 Show Figure 5 Schematic diagram of the quantization process of the reference voltage acquisition circuit; Figure 7 Show Figure 4 A schematic diagram of another implementation of a reference voltage acquisition circuit in a display device; Figure 8 Show Figure 7 Schematic diagram of the quantization process of the reference voltage acquisition circuit; Fig. 9 Show Figure 4 A schematic diagram of an implementation of an error self-correction circuit in a display device; Fig.10 Show Figure 4 A schematic diagram of another implementation of an error self-correction circuit in a display device; Fig.11 A schematic diagram showing an embodiment of an error transmission architecture in a display device provided according to an embodiment of the present application is shown; Fig.12 A schematic flow chart of a LED driving self-correction method provided according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0028] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear at different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0029] In the description of the present application, the words "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments. "Multiple" herein refers to two or more than two. In addition, in order to facilitate the clear description of the technical solutions of the embodiments of the present application, the words "first" and "second" are used to distinguish between the same items or similar items with substantially the same functions and effects. Those skilled in the art will understand that the words "first" and "second" do not limit the quantity and execution order, and the words "first" and "second" do not limit them to be necessarily different.

[0030] In addition, the same figure marks in the figures represent the same or similar structures, and thus their repeated description will be omitted. That is, the various parts in this specification are described in a combination of parallel and progressive manners, and each part focuses on the differences from other parts. The same or similar parts between the various parts can be referenced to each other.

[0031] Figure 1 A schematic diagram of a display device is shown. Figure 2 Shows Figure 1 A timing diagram of some driving signals in a display device. Figure 3 Shows Figure 1 Schematic diagram of the timing of the actual pre-charge voltage in the display device.

[0032] refer to Figure 1 , Figure 2 and Figure 3 , an LED display screen 130 is provided with an array of LED lamp beads (also referred to as LED in this article) with m rows and n columns. When displaying, multiple row drive signals ROW[1]~ROW[m] control multiple power tubes Q11~Q1m to turn on in sequence, thereby controlling the m row drive lines on the LED display screen 130 to turn on in sequence. When a row drive line is in the on state, multiple column drive signals PWM[0]~PWM[n] control multiple switch tubes Q21~Q2n to turn on in sequence / simultaneously, thereby controlling the n column drive lines on the LED display screen 130 to turn on in sequence / simultaneously, connecting the current paths of the LED lamp beads on the corresponding rows and columns, and the current flows through the LED lamp beads to make the LED lamp beads emit light. In order to enable the LED display screen 130 to have a better display effect, before the corresponding column drive line is turned on, the pre-charge signal Tpre will first control the multiple switch tubes Q31~Q3n to turn on, thereby pre-charging the LED lamp beads to a preset voltage, that is, the pre-charge voltage Vpre.

[0033] In practical applications, the LED display screen 130 may be provided with m rows and a*n columns of LED lamp beads, where a is an integer greater than or equal to 1, and each of the m rows and n columns of LED lamp beads is driven by a column driver chip 120. Accordingly, the display device 100 includes a plurality of column driver chips 120, and each column driver chip 120 is provided with a pre-charge voltage Vpre, that is, Figure 1 Only part of the display screen architecture and column driver chip architecture in the display device 100 is shown.

[0034] The display device 100 has a relatively high requirement on the accuracy of the pre-charge voltage Vpre, and different pre-charge voltages Vpre will result in different chip brightness. Figure 3, each LED lamp bead will have a parasitic capacitance C to the ground. The characteristics of the LED lamp beads used on the same LED display screen 130 are the same, so the forward conduction voltage (recorded as VF) of each LED lamp bead is equal. Taking LED lamp bead D11 as an example, each time the LED lamp bead D11 is turned on, the current output by the constant current source I1 will have a current of C*(VF-Vpre) that is charged to the parasitic capacitance C of the LED lamp bead D11, rather than flowing through the LED lamp bead D11. Therefore, if the pre-charge voltage Vpre provided by each column driver chip 120 to the LED display screen 130 is different, different charges will be charged to the parasitic capacitance of the LED lamp bead. For example, during the effective period of the pre-charge signal Trep, some column driver chips output the pre-charge voltage Vpre1 ​​to the LED lamp bead, and the other column driver chips output the pre-charge voltage Vpre2 to the LED lamp bead. At this time, according to the different pre-charge voltages Vpre provided by the column driver chips, the current flowing through the LED lamp bead will be different, so that obvious color blocks will be seen on the LED display screen 130.

[0035] In order to reduce the impact of color blocks on the display effect, the pre-charge voltage Vpre output by each column driver chip needs to be adjusted. The common method is to adjust. After the column driver chip is manufactured, the pre-charge voltage Vpre of each column driver chip is corrected by efuse (Electronic Fuse) or OTP (One-Time Programmable) and other methods, so as to reduce the impact of color blocks. However, the adjustment process is carried out when the chip leaves the factory. After the chip adjustment is completed, the chip is sent to the client, and the customer will weld the chip to the display light board. During the welding process, the column driver chip will be in a high temperature environment. This high temperature process will cause the thermal expansion and contraction of the structural materials such as the plastic packaging material of the column driver chip, thereby causing the column driver chip to be affected by stress, and the output pre-charge voltage Vpre will deviate from the target value, and ultimately the display effect of the display screen will not reach the ideal state.

[0036] In view of the above problems, the present application improves the structure of the column driver chip (also referred to as the driver chip or chip in this document) in the display device. Figure 4 , Figure 4 The structure diagram of the display device provided by the embodiment of the present application is shown. By driving the chip ( Figure 4Only one column driver chip 220 is shown, and other column driver chips in the display device 200 have the same internal structure as the column driver chip 220, and can be understood by reference to each other). An LED driver self-correction circuit is added to self-correct the pre-charge voltage of the chip to the LED lamp bead, so that the final pre-charge voltage (i.e., the target pre-charge voltage) output by each column driver chip to the LED display screen (or LED display screen) 230 is consistent, effectively eliminating the color blocks on the display screen and avoiding the influence of high temperature on the chip output parameters during the chip welding process.

[0037] like Figure 4 As shown, in this embodiment, the display device 200 includes: a row driver chip 210, a column driver chips 220 and an LED display screen 230.

[0038] The LED display screen 230 includes m row drive lines, a*n column drive lines, and an LED lamp bead array consisting of m*(a*n) lamp beads, and the m*(a*n) lamp beads are respectively arranged at the intersection of the m row drive lines and the a*n column drive lines, where a, m and n are all integers greater than or equal to 1. Since the a column drive chips 220 have the same internal structure, in order to simplify the drawings, Figure 4 Only one column driver chip 220, n column driver lines connected to n constant current output channels of the column driver chip 220, and a plurality of LED lamp beads D11 to Dmn corresponding to the n column driver lines are shown in the figure, and in this embodiment, only Figure 4 The column driver chip 220 shown in FIG. 1 is used as an example to explain the technical solution. For other embodiments in which the display device 200 includes multiple column driver chips, that is, a is greater than 1, Figure 4 The above solution is obtained by simple expansion.

[0039] In addition, it should be noted that Figure 4 In the LED display screen 230 shown, each LED lamp bead is connected to a common cathode, that is, the cathodes of the LED lamp beads in the same row are connected to the same row drive line, and the anodes are connected to different column drive lines respectively, but other implementations are also possible. For example, each LED lamp bead can also be connected to a common anode, that is, the anodes of the LED lamp beads in the same row are connected to the same row drive line, and the cathodes are connected to different column drive lines respectively. This application does not impose strict restrictions on this.

[0040] The row driver chip 210 includes m row scan switches Q11~Q1m, which are respectively connected to m row driver lines. The m row scan switches Q11~Q1m are controlled by multiple row driver signals (also called row scan signals) ROW[1]~ROW[m] to open the m row driver lines in sequence, for example, connecting the ground path of each row driver line in sequence in each display frame.

[0041] In terms of internal structure, the internal structure of each column driver chip in the a column driver chips 220 is basically the same, and each column driver chip 220 includes n constant current sources I1~In, n column driver switches Q21~Q2n, n pre-charge switches Q31~Q3n, a buffer 221, and an LED driver self-correction circuit 222. In terms of output pins, the column driver chip 220 includes n constant current output terminals and n pre-charge output terminals, the n constant current output terminals are used to connect to n column driver lines respectively to provide constant current drive signals to the n column driver lines, and the n pre-charge output terminals are used to connect to the n column driver lines respectively to provide pre-charge voltages to the n column driver lines; in some other embodiments, the n constant current output terminals and the n pre-charge output terminals share n output terminals, in which case the n output terminals are used to connect to n column driver lines respectively, and each output terminal can output constant current drive signals and pre-charge voltages to the corresponding connected column driver lines in a time-sharing manner. Figure 4 The example shown is only described by taking the example that the column driver chip 220 has n constant current output terminals and n pre-charge output terminals at the same time.

[0042] exist Figure 4 In the example shown, n column drive switches Q21~Q2n are respectively connected between n constant current sources I1~In and n constant current output terminals, n pre-charge switches Q31~Q3n are respectively connected between the output terminal of the buffer 221 and the n pre-charge outputs, the n column drive switches Q21~Q2n are controlled by multiple column drive signals PWM[1]~PWM[n] to turn on n column drive lines in sequence / simultaneously, and provide constant current signals to the anodes of the LED lamp beads connected to the column drive lines while the column drive lines are in the turned-on state, and the n pre-charge switches Q31~Q3n are controlled by the pre-charge signal Tpre to pre-charge the potential of the column drive lines (i.e., the anode potential of the LED lamp beads connected to the column drive lines) to the target pre-charge voltage Vpre1 ​​before the column drive lines are turned on.

[0043] The LED driving self-correction circuit 222 is used to self-correct the pre-charge voltage Vpre0 pre-charged to the LED lamp beads by the column driving chip 220, so that the column driving chip 220 outputs the target pre-charge voltage Vpre1. The input end of the buffer 221 is connected to the output end of the LED driving self-correction circuit 222, and is used to buffer and output the target pre-charge voltage Vpre1 ​​output by the LED driving self-correction circuit 222.

[0044] The LED driver self-correction circuit 222 further includes: a reference voltage acquisition circuit 223, an error acquisition circuit 224 and an error self-correction circuit 225. The reference voltage acquisition circuit 223 is used to obtain the correction reference voltage Vref_pre1 of the column driver chip 220 according to the average forward conduction voltage of the multiple LED lamp beads D11~Dmn connected to the column driver chip 220; the error acquisition circuit 224 is used to obtain the error Diff_D of the correction reference voltage Vref_pre1 of the column driver chip 220 relative to the reference voltage Vref_pre0; the error self-correction circuit 225 is used to add the pre-charge voltage Vpre0 of the column driver chip 220 and the corresponding error Diff_D to obtain the target pre-charge voltage Vpre1 ​​of the column driver chip 220, so as to correct the pre-charge voltage Vpre0 of the column driver chip 220. The correction reference voltage Vref_pre1 and the error Diff_D are both digital signals. It should be noted that the digital signal described in this article can also be understood as a digital code.

[0045] It can be understood that when the embodiment of the present application performs self-calibration on the pre-charge voltage of a column driver chips 220 in the display device 200, for each column driver chip 220, the correction reference voltage Vref_pre1 of the column driver chip 220 is obtained according to the average forward conduction voltage of multiple LED lamp beads connected to the column driver chip 220. For example, the average forward conduction voltage of multiple LED lamp beads connected to the column driver chip is used as its correction reference voltage Vref_pre1. After the column driver chip 220 is welded to the display light board, the error of the correction reference voltage Vref_pre1 of the column driver chip 220 relative to the correction reference voltage Vref_pre0 of any selected column driver chip can be calculated, and the initial pre-charge voltage Vpre0 output by the column driver chip 220 is added to the corresponding error, so that the final pre-charge voltage (i.e., the target pre-charge voltage) Vpre1 ​​output by the column driver chip 220 to the LED display screen is consistent with other column driver chips 220, thereby effectively eliminating the color blocks on the display screen and avoiding the influence of high temperature on chip output parameters during chip welding.

[0046] In some embodiments, the reference voltage acquisition circuit 223 is configured to: sequentially collect the forward conduction voltages VF of multiple LED lamp beads D11~Dmn connected to the corresponding column driver chip 220, and average the forward conduction voltages of the multiple LED lamp beads D11~Dmn to obtain the correction reference voltage Vref_pre1 of the column driver chip 220.

[0047] When implementing it, Figure 5As shown, the reference voltage acquisition circuit 223 includes: an analog-to-digital converter 2231, a memory 2232, and a processing unit 2233. The analog-to-digital converter 2231 is used to collect the forward conduction voltage VF of the LED lamp bead when the LED lamp bead is lit, and quantize it into a corresponding digital signal. The memory 2232 is used to store the digital signal of the forward conduction voltage VF of the LED lamp bead. The processing unit 2233 is used to average the digital signals of the forward conduction voltages of the plurality of LED lamp beads D11~Dmn stored, and obtain the correction reference voltage Vref_pre1 of the column driver chip 220.

[0048] Optionally, the reference voltage used by the analog-to-digital converter 2231 when converting analog signals to digital signals is the pre-charge voltage (i.e., the initial pre-charge voltage) Vpre0 before self-calibration. The initial pre-charge voltage Vpre0 can be provided by a pre-charge voltage generating circuit arranged inside or outside the column driver chip 220, for example. If the error of the initial pre-charge voltage Vpre0 is considered, the initial pre-charge voltage Vpre0 can be expressed as Vpre*(1+δ), where δ represents the error term of the initial pre-charge voltage Vpre0.

[0049] Combination Figure 5 and Figure 6 In this embodiment, the working process of the reference voltage acquisition circuit 223 is roughly as follows: First, after the display device 200 is powered on, the row drive signal ROW[1] is set to a valid state (such as logic 1), and the row drive switch Q11 is controlled to open the first row drive line, connecting the cathodes of the first row of LED lamp beads D11~D1n to the reference ground; Next, during the period when the first row of driving lines is turned on, the n column driving signals PWM[1]~PWM[n] are set to be valid states (such as logic 1) in sequence, the n column driving lines are turned on in sequence, the constant current signals are output to the first row of LED lamp beads D11~D1n in sequence, and the forward conduction voltage VF of the LED lamp beads is collected in sequence by using the analog-to-digital converter 2231 when each LED lamp bead is lit. 1i (Table 1 below represents the 1st row, i represents the ith column, and i is an integer greater than or equal to 1 and less than or equal to n), and after analog-to-digital conversion (i.e. quantization), the forward conduction voltage in the form of a digital signal (i.e. the quantized value or digital code of the forward conduction voltage) is output to the memory 2232, thereby storing the digital code of the forward conduction voltage of the LED lamp beads D11~D1n in the 1st row; Afterwards, the above process is repeated to collect and store the digital codes of the forward conduction voltages of the LED lamp beads in the 2nd row to the mth row in sequence; Finally, the processing unit 2233 is used to average the stored digital signals of the forward conduction voltages of the LED lamp beads in each row to obtain the correction reference voltage Vref_pre1 of the column driver chip 220 .

[0050] It can be understood that the reference voltage acquisition circuit 223 disclosed in this embodiment is relatively flexible in collecting and quantifying the forward conduction voltages of the plurality of LED lamp beads D11 -Dmn.

[0051] In other embodiments, the LED driving self-correction circuit 222 includes a plurality of sampling capacitors respectively connected in parallel with a plurality of LED lamp beads D11~Dmn. In this case, the reference voltage acquisition circuit 223 is configured as follows: taking rows as units, after collecting the forward conduction voltage of each row of LED lamp beads based on the plurality of sampling capacitors in each row, the plurality of sampling capacitors in each row are controlled to be connected in parallel to obtain the average conduction voltage of each row of LED lamp beads, and the average conduction voltage of the plurality of rows of LED lamp beads is averaged to obtain the correction reference voltage Vref_pre1 of the column driver chip 220.

[0052] When implementing it, Figure 7 As shown, the reference voltage acquisition circuit 223 includes: multiple sampling capacitors, multiple first switches, multiple second switches, an analog-to-digital converter 2234, a memory 2235, and a processing unit 2236. Among them, the multiple first switches are respectively connected between the multiple LED lamp beads D11~Dmn and the first ends of the multiple sampling capacitors, the second ends of the multiple sampling capacitors are connected to the corresponding row drive lines, the multiple first switches are controlled by the first control signal PS and are in a closed state in the first time period during the effective period of the row drive signal of the corresponding row, so as to connect the multiple sampling capacitors of the corresponding row to the forward conduction voltage of the multiple LED lamp beads. The multiple second switches are respectively connected between the first node A and the first ends of the multiple sampling capacitors, and the multiple second switches are controlled by the second control signal PH and are in a closed state in the second time period during the effective period of the row drive signal of the corresponding row, so as to control the multiple sampling capacitors of the corresponding row to be in a parallel state. The input end of the analog-to-digital converter 2234 is connected to the first node A, and is used to quantize the average conduction voltage of each row of LED lamp beads into a corresponding digital signal. The memory 2235 is used to store the digital signal of the average conduction voltage of each row of LED lamp beads. The processing unit 2236 is used to average the digital signals of the average conduction voltages of the stored multiple rows of LED lamp beads to obtain the correction reference voltage Vref_pre1 of the column driver chip 220 .

[0053] Combination Figure 7 and Figure 8 In this embodiment, the working process of the reference voltage acquisition circuit 223 is roughly as follows: First, after the display device 200 is powered on, the row drive signal ROW[1] is set to a valid state (such as logic 1), and the row drive switch Q11 is controlled to open the first row drive line, connecting the cathodes of the first row of LED lamp beads D11~D1n to the reference ground; Next, in the first stage during the opening of the first row of driving lines, the first control signal PS is set to a valid state (such as logic 1), and the second control signal PH is set to an invalid state (such as logic 0), and the plurality of sampling capacitors C11~C1n in the first row are connected to the collection channel of the forward conduction voltage of the plurality of LED lamp beads D11~D1n in the first row, and the constant current signal is simultaneously output to the plurality of sampling capacitors C11~C1n in the first row, and the forward conduction voltage VF of the plurality of LED lamp beads D11~D1n in the first row is respectively obtained on the plurality of sampling capacitors C11~C1n in the first row. 11 ~VF 1n ;

[0054] Secondly, in the second stage during the opening of the first row driving line, the second stage is later than the first stage, the first control signal PS is set to an invalid state (such as logic 0), the second control signal PH is set to a valid state (such as logic 1), the multiple sampling capacitors C11~C1n of the first row are disconnected from the forward conduction voltage collection channel of the multiple LED lamp beads D11~D1n of the first row, and the multiple sampling capacitors C11~C1n of the first row are set to a parallel state, so that according to the charge conservation principle, the average conduction voltage of the multiple LED lamp beads D11~D1n of the first row is obtained at the first node A. , and after analog-to-digital conversion (i.e. quantization), the average on-state voltage of multiple LED lamp beads D11~D1n in the first row (i.e. the average on-state voltage of the LED lamp beads in the first row) is output in the form of a digital signal. quantized value or digital code) D to the memory 2235, thereby generating a digital signal D of the average conduction voltage of the LED lamp beads in the first row To store; After that, the above process is repeated to collect and store the digital signal D of the average conduction voltage of each LED lamp bead in the 2nd row to the mth row in turn. ; Finally, the processing unit 2236 is used to store the digital signal D of the average conduction voltage of each row of LED lamp beads. An averaging process is performed to obtain the calibration reference voltage Vref_pre1 of the column driver chip 220 .

[0055] It can be understood that the reference voltage acquisition circuit 223 disclosed in this embodiment requires less processing time for collecting and quantifying the forward conduction voltages of the plurality of LED lamp beads D11 to Dmn, which can improve conversion efficiency and reduce self-correction time.

[0056] Optionally, the reference voltage used by the analog-to-digital converter 2234 when converting analog signals to digital signals is the pre-charge voltage (i.e., the initial pre-charge voltage) Vpre0 before self-calibration. The initial pre-charge voltage Vpre0 can be provided by a pre-charge voltage generating circuit arranged inside or outside the column driver chip 220, for example. If the error of the initial pre-charge voltage Vpre0 is considered, the initial pre-charge voltage Vpre0 can be expressed as Vpre*(1+δ), where δ represents the error term of the initial pre-charge voltage Vpre0.

[0057] by Figure 7 Taking the reference voltage acquisition circuit 223 shown in FIG. 2 as an example, the digital signal D of the average conduction voltage of each row of LED lamp beads obtained by the circuit 223 is (j represents the number of rows, j is a positive integer greater than or equal to 1 and less than or equal to m) can be expressed as: D (1),

[0058] And the calibration reference voltage Vref_pre1 of the column driver chip 220 obtained therefrom can be expressed as: (2), in, It represents the average forward conduction voltage of each LED lamp bead in the display area controlled by the column driver chip 220 (that is, each LED lamp bead connected to the column driver chip 220 in the LED display screen 130), and in the entire lamp board, Usually a constant.

[0059] In this embodiment, the reference voltage Vref_pre1 used by the column driver chip 220 can be selected as the calibration reference voltage of any column driver chip among the a column driver chips of the display device 200, and the a column driver chips select the same reference voltage Vref_pre0. For example, when a is greater than 1, that is, when the display device 200 includes two or more column driver chips 220, the display device 200 is further provided with an error transmission architecture. After obtaining the calibration reference voltage Vref_pre1 of each column driver chip among the a column driver chips of the display device 200 by using the above-mentioned embodiments, the calibration reference voltage Vref_pre1 of a column driver chip (for example, the first column driver chip) is selected as the reference voltage Vref_pre0, and the column driver chip sends the reference voltage Vref_pre0 (that is, the calibration reference voltage Vref_pre1 obtained by it) to each column driver chip in the form of a register, so that all chips will receive the calibration reference voltage Vref_pre1 (that is, the reference voltage Vref_pre0) of the first column driver chip. Optionally, the sending process may be to first send the correction reference voltage Vref_pre1 (i.e., reference voltage Vref_pre0) of the first column driver chip to the control card, and then the control card sends it to each column driver chip; or the user may read back the correction reference voltage Vref_pre1 (i.e., reference voltage Vref_pre0) of the first column driver chip, and then send it to all column driver chips through a register.

[0060] For example, in Fig.11 In the example shown, the column driver chip 220 in the display device 200 includes, for example, a column driver chip 220_0, a column driver chip 220_1, a column driver chip 220_2, ..., a column driver chip 220_a, and the display device 200 further includes a control card 30, which is connected to each column driver chip, receives a calibration reference voltage output by one of the column driver chips (such as the column driver chip 220_0), and sends the received calibration reference voltage to each column driver chip as a reference voltage Vref_pre0 required for each column driver chip when performing pre-charge voltage self-calibration. Optionally, the control card 30 can be integrated with a column driver chips, or integrated in one of the a column driver chips, or can be set separately.

[0061] In addition, in some other embodiments, the control card 30 may not be provided in the display device 200. Instead, a column driver chips may be arranged to adopt a cascade transmission method to transmit the calibration reference voltage output by one of the column driver chips to each other column driver chip respectively, so as to serve as the reference voltage Vref_pre0 required by each column driver chip when performing pre-charge voltage self-calibration.

[0062] It should be noted that in the aforementioned embodiments, there is no limitation on the signal transmission protocol that can be used between the column driver chips, or between the control card 30 and the column driver chips. For example, a single bus transmission protocol, I2C protocol, SPI protocol, or other multi-line transmission protocols, high-speed transmission protocols, etc. can be used.

[0063] For example, the reference voltage Vref_pre0 can be sent to the error acquisition circuit 224 in the LED driver self-calibration circuit in each column driver chip, so that the error acquisition circuit 224 determines the error Diff_D of the calibration reference voltage Vref_pre1 of the corresponding column driver chip relative to the reference voltage Vref_pre0. Fig.11 Taking the column driver chip 220_1 as an example, the error acquisition circuit 224 inside the column driver chip 220_1 can obtain the error Diff_D of the correction reference voltage Vref_pre1 of the column driver chip 220_1 relative to the reference voltage Vref_pre0 by making a difference between the correction reference voltage Vref_pre1 and the reference voltage Vref_pre0 in the column driver chip 220_1. The error Diff_D can be expressed as: (3),

[0064] Wherein, δ1 and δ2 are the error terms when the column driver chip 220_0 and the column driver chip 220_1 generate the pre-charge voltage, respectively.

[0065] In some embodiments, reference Fig. 9 , the error self-correction circuit 225 further includes: a digital-to-analog converter 2251 and an adder 2252. The first input terminal of the digital-to-analog converter 2251 receives the digital error signal Diff_D, the second input terminal of the digital-to-analog converter 2251 receives the reference signal VREF, and the digital-to-analog converter 2251 is used to convert the digital error signal Diff_D into an analog error signal Diff_A according to the reference signal VREF, wherein the digital error signal Diff_D is a digital signal representation of the error; the first input terminal of the adder 2252 receives the pre-charge voltage Vpre0, the second input terminal of the adder 2252 receives the analog error signal Diff_A, and the output terminal of the adder 2252 outputs the target pre-charge voltage Vpre1.

[0066] Taking the column driver chip 220_1 as an example, after the error acquisition circuit 224 therein acquires the corresponding error Diff_D, the error Diff_D is sent to the digital-to-analog converter 2251 in the error self-correction circuit 225 in the form of a digital signal. The digital-to-analog converter 2251 converts the error Diff_D into a corresponding analog signal Diff_A based on the reference voltage VREF, and uses the adder 2252 to add the error in the form of the analog signal (i.e., the analog error signal) Diff_A and the initial pre-charge voltage Vpre0 of the column driver chip 220_1, so as to obtain the target pre-charge voltage Vpre1 ​​of the column driver chip 220_1, which can be expressed as:

[0067] (4),

[0068] Wherein, δ1 and δ2 represent the error terms of the column driver chip 220_0 and the column driver chip 220_1 when generating the pre-charge voltage, respectively, and γ represents the error term of the reference voltage VREF.

[0069] In the above formula (4), δ1, δ2 and γ can all be regarded as infinitesimal quantities, so the product of any two of δ1, δ2 and γ can be ignored in the above formula (4). At this time, the above formula (4) can be simplified to: (5).

[0070] In formula (5), if =0, that is, the reference voltage VREF of the digital-to-analog converter 2251 is configured as VREF= , then the target pre-charge voltage Vpre1 ​​of the column driver chip 220_1 will eventually become Vpre0(1+δ1), that is, the target pre-charge voltages of the column driver chip 220_0 and the column driver chip 220_1 will become consistent. Similarly, the self-calibrated target pre-charge voltages of all column driver chips in the display setting 200 will become Vpre0(1+δ1), thereby effectively eliminating the color blocks on the light board.

[0071] In other embodiments, reference Fig.10The error self-correction circuit 225 further includes: a scaling unit 2253, a digital adder 2254, and a digital-to-analog converter 2255. Among them, the first input end of the scaling unit 2253 receives the digital error signal Diff_D, the second input end of the scaling unit 2253 receives the scaling factor k0, and the scaling unit 2253 is used to scale the digital error signal Diff_D according to the scaling factor k0 to obtain a scaling signal (recorded as bit1) of the digital error signal, and the digital error signal Diff_D is a digital signal representation of the error; the first input end of the digital adder 2254 receives the scaling signal bit1, the second input end of the digital adder 2254 receives the digital adjustment signal bit0, and the output end of the digital adder 2254 outputs a digital correction signal bit2, and the digital adjustment signal bit0 represents the initial correction of the error term of the column driver chip; the input end of the digital-to-analog converter 2255 receives the digital correction signal bit2, and the digital-to-analog converter 2255 is used to convert the digital correction signal bit2 into an analog correction signal and output it to the pre-charge voltage output node B of the column driver chip 220 to obtain the target pre-charge voltage Vpre1. The digital-to-analog converter 2255 includes N current sources (I, 2I, . . . , NI) and N switches. The N switches are controlled by the digital correction signal bit2 and are turned on accordingly, thereby realizing the digital-to-analog conversion function.

[0072] Compared to Fig. 9 In the example shown, in this embodiment, a scaling unit 2253 and a digital adder 2254 are provided in the error self-correction circuit 225. During self-correction, the digital error signal Diff_D can be scaled by multiplying the digital error signal Diff_D by a preset register scaling coefficient, so as to modify the error more flexibly. Then, the scaling signal bit1 obtained after scaling is added to the digital adjustment signal bit0, and the final error digital code, i.e., the digital correction signal bit2, is sent to the digital-to-analog converter 2255. The digital-to-analog converter 2255 uses N current sources (I, 2I, ..., NI) and N switches to perform digital-to-analog conversion on the error digital code and then superimposes it on the pre-charge voltage output node B of the column driver chip, wherein the pre-charge voltage output node B is a connection node between the pre-charge current source Ipre and the resistor R in the column driver chip. The column driver chip 220 generates an initial pre-charge voltage Vpre0 at both ends of the resistor R based on the pre-charge current source Ipre. After self-correction, the column driver chip 220 outputs a target pre-charge voltage Vpre1 ​​at the node B. In this embodiment, the digital trimming signal bit0 can trim the pre-charge voltage Vpre0 of the chip in the FT phase to correct the initial pre-charge voltage.

[0073] It can be understood that this embodiment can achieve Fig. 9On the basis of the same self-correction function as the example shown, the pre-charge voltage can also be adjusted. While ensuring that the target pre-charge voltages of self-correction of all column driver chips in the display setting 200 are consistent, thereby eliminating color blocks on the light board, the accuracy of the pre-charge voltage output by the column driver chip is further improved, and the solution is simpler and more practical.

[0074] Furthermore, the present application also discloses a self-calibration method for LED driving, which is applied to the display device 200 shown in the above embodiments. Fig.12 The method includes performing the following steps on each column driver chip in the display device 200:

[0075] In step S10, a calibration reference voltage of the column driver chip is obtained according to an average forward conduction voltage of a plurality of LED lamp beads connected to the column driver chip.

[0076] In step S20 , an error of a calibration reference voltage of a column driver chip relative to a base voltage is obtained.

[0077] In this step, the reference voltage is a calibration reference voltage of any column driver chip.

[0078] In step S30, the pre-charge voltage and the error are added to obtain a target pre-charge voltage of the column driver chip, thereby achieving correction of the pre-charge voltage of the column driver chip.

[0079] In some embodiments, step S10 further includes: collecting the forward conduction voltage of each LED lamp bead in the multiple LED lamp beads one by one; averaging the forward conduction voltages of the multiple LED lamp beads to obtain a correction reference voltage of the driver chip.

[0080] In some embodiments, step S10 further includes: collecting the forward conduction voltage of each row of LED lamp beads row by row based on multiple sampling capacitors connected in parallel with multiple LED lamp beads; controlling multiple sampling capacitors in each row in parallel to obtain the average conduction voltage of each row of LED lamp beads; averaging the average conduction voltage of multiple rows of LED lamp beads to obtain a correction reference voltage for the driver chip.

[0081] In specific implementation, the specific implementation of each step in the LED driving self-calibration method described above and the technical effects that can be achieved can be found in the various embodiments of the display device 200 described above, and will not be repeated here.

[0082] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present application, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present application.

Claims

1. An LED driver self-correction circuit, used for self-correcting the pre-charge voltage pre-charged from the column driver chip to the LED lamp bead, the LED driver self-correction circuit comprising: A reference voltage acquisition circuit, used for obtaining a correction reference voltage of the column driver chip according to an average forward conduction voltage of a plurality of LED lamp beads connected to the column driver chip; An error acquisition circuit, used for acquiring an error of the correction reference voltage relative to a reference voltage; The error self-correction circuit is used to perform an addition process on the pre-charge voltage and the error to obtain a target pre-charge voltage of the column driver chip and realize correction of the pre-charge voltage.

2. The LED driving self-correction circuit according to claim 1, wherein: The reference voltage is a calibration reference voltage of any column driver chip.

3. The LED driving self-correction circuit according to claim 1, wherein: The correction reference voltage and the error are both digital signals.

4. The LED driving self-correction circuit according to claim 3, wherein: The reference voltage acquisition circuit is configured as follows: The forward conduction voltages of the plurality of LED lamp beads are collected in sequence, and the forward conduction voltages of the plurality of LED lamp beads are averaged to obtain the correction reference voltage.

5. The LED driving self-correction circuit according to claim 1, wherein: The LED driving self-correction circuit comprises a plurality of sampling capacitors respectively connected in parallel with the plurality of LED lamp beads; The reference voltage acquisition circuit is configured as follows: Taking rows as units, after collecting the forward conduction voltage of each row of LED lamp beads based on the multiple sampling capacitors in each row, the multiple sampling capacitors in each row are controlled to be connected in parallel to obtain the average conduction voltage of each row of LED lamp beads, and the average conduction voltages of multiple rows of LED lamp beads are averaged to obtain the correction reference voltage.

6. The LED driving self-correction circuit according to claim 4, wherein: The reference voltage acquisition circuit comprises: The analog-to-digital converter is used to collect the forward conduction voltage of the LED lamp bead when the LED lamp bead is lit, and quantize it into a corresponding digital signal; A memory, used to store a digital signal of the forward conduction voltage of the LED lamp bead; The processing unit is used to average the stored digital signals of the forward conduction voltages of the plurality of LED lamp beads to obtain the correction reference voltage.

7. The LED driving self-correction circuit according to claim 5, wherein: The reference voltage acquisition circuit comprises: A plurality of first switches are respectively connected between the plurality of LED lamp beads and the plurality of sampling capacitors, and the plurality of first switches are controlled by a first control signal and are in a closed state in a first time period during which the row driving signal of the corresponding row is effective, so as to connect the plurality of sampling capacitors of the corresponding row to the collection channel of the forward conduction voltage of the plurality of LED lamp beads; A plurality of second switches are respectively connected between the first node and the plurality of sampling capacitors, the plurality of second switches are controlled by a second control signal and are in a closed state during a second time period when the row driving signal of the corresponding row is valid, so as to control the plurality of sampling capacitors of the corresponding row to be in a parallel state; An analog-to-digital converter, whose input terminal is connected to the first node, is used to quantize the average conduction voltage of each row of LED lamp beads into a corresponding digital signal; A memory, used to store a digital signal of the average conduction voltage of each row of LED lamp beads; The processing unit is used to average the digital signals of the average conduction voltages of the stored multiple rows of LED lamp beads to obtain the correction reference voltage.

8. The LED driving self-correction circuit according to claim 3, wherein: The error self-correction circuit comprises: A digital-to-analog converter, wherein a first input terminal receives a digital error signal and a second input terminal receives a reference signal, wherein the digital-to-analog converter is used to convert the digital error signal into an analog error signal, wherein the digital error signal is a digital signal representation of the error; An adder, wherein a first input terminal receives the pre-charge voltage, a second input terminal receives the analog error signal, and an output terminal outputs the target pre-charge voltage.

9. The LED driving self-correction circuit according to claim 3, wherein: The error self-correction circuit comprises: A scaling unit, wherein a first input terminal receives a digital error signal and a second input terminal receives a scaling factor, wherein the scaling unit is used to scale the digital error signal according to the scaling factor to obtain a scaled signal of the digital error signal, wherein the digital error signal is a digital signal representation of the error; A digital adder, having a first input terminal receiving the scaling signal, a second input terminal receiving a digital trimming signal, and an output terminal outputting a digital correction signal, wherein the digital trimming signal represents an error term of the column driver chip; A digital-to-analog converter receives the digital correction signal at its input end, and is used to convert the digital correction signal into an analog correction signal and output the analog correction signal to the precharge voltage output node of the column driver chip to obtain the target precharge voltage.

10. A LED driver self-calibration method, comprising: Obtaining a calibration reference voltage of the column driver chip according to an average forward conduction voltage of a plurality of LED lamp beads connected to the column driver chip; Obtaining an error of a calibration reference voltage of the column driver chip relative to a reference voltage; The pre-charge voltage is added to the error to obtain a target pre-charge voltage of the column driver chip, thereby correcting the pre-charge voltage of the column driver chip.

11. The LED driving self-calibration method according to claim 10, wherein: The reference voltage is a calibration reference voltage of any column driver chip.

12. The LED driving self-calibration method according to claim 10, wherein: Obtaining a correction reference voltage of the column driver chip according to an average forward conduction voltage of a plurality of LED lamp beads connected to the column driver chip comprises: Collecting the forward conduction voltage of each LED lamp bead in the plurality of LED lamp beads one by one; The forward conduction voltages of the plurality of LED lamp beads are averaged to obtain the correction reference voltage.

13. The LED driving self-calibration method according to claim 10, wherein: Obtaining a correction reference voltage of the column driver chip according to an average forward conduction voltage of a plurality of LED lamp beads connected to the column driver chip comprises: Based on a plurality of sampling capacitors connected in parallel to the plurality of LED lamp beads, the forward conduction voltage of each row of LED lamp beads is collected row by row; Controlling the plurality of sampling capacitors in each row to be connected in parallel to obtain an average conduction voltage of each row of LED lamp beads; The average conduction voltages of the multiple rows of LED lamp beads are averaged to obtain the correction reference voltage.

14. A column driver chip, comprising: The LED driving self-correction circuit according to any one of claims 1 to 9.

15. A display device comprising: At least one column driver chip as claimed in claim 14.

16. The display device according to claim 15, wherein: When the number of the column driver chips is 2 or more, the display device further includes: The control card is connected to each column driver chip respectively, receives a calibration reference voltage output by one of the column driver chips, and sends the received calibration reference voltage to each column driver chip to serve as a reference voltage of each column driver chip.

17. The display device according to claim 15, wherein: When the number of the column driver chips is 2 or more, the 2 or more column driver chips transmit the calibration reference voltage output by one of the column driver chips to each column driver chip respectively through cascade transmission to serve as the reference voltage of each column driver chip.

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