WO2020010684A1 - Led显示装置及其驱动方法 - Google Patents

Led显示装置及其驱动方法 Download PDF

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Publication number
WO2020010684A1
WO2020010684A1 PCT/CN2018/104267 CN2018104267W WO2020010684A1 WO 2020010684 A1 WO2020010684 A1 WO 2020010684A1 CN 2018104267 W CN2018104267 W CN 2018104267W WO 2020010684 A1 WO2020010684 A1 WO 2020010684A1
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WIPO (PCT)
Prior art keywords
led
voltage
constant current
led lamps
row
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PCT/CN2018/104267
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English (en)
French (fr)
Inventor
罗正
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杭州视芯科技有限公司
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Priority to US16/626,397 priority Critical patent/US11049441B2/en
Publication of WO2020010684A1 publication Critical patent/WO2020010684A1/zh

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0264—Details of driving circuits
    • G09G2310/0275—Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0264—Details of driving circuits
    • G09G2310/0294—Details of sampling or holding circuits arranged for use in a driver for data electrodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G09G2330/021—Power management, e.g. power saving
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/08—Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/10—Dealing with defective pixels
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/12—Test circuits or failure detection circuits included in a display system, as permanent part thereof

Definitions

  • the present invention relates to LED display technology, and more particularly, to an LED display device and a driving method thereof.
  • LED display devices have been widely used in the display field.
  • LED display devices have the following advantages: high brightness, wide viewing angle, rich colors, and customizable screen shapes, which are widely used in various fields such as industry, transportation, commercial advertising, information release, sports games and so on.
  • the pixel element used in the LED display device is an LED lamp, wherein a plurality of LED lamps constitute a pixel array.
  • the LED display device scans in rows and connects the constant current source and the selected LED in series, respectively, so as to light up the LEDs in the corresponding row.
  • the current control method and the on-time control method are used to control the brightness of the selected LED, thereby achieving multi-level grayscale.
  • the brightness is controlled by adjusting the magnitude of the current flowing in the LED.
  • the on-time control method is to control the brightness of the LED by changing the duty cycle in the case of constant current driving.
  • the LED display device often needs to work for a long time, and sometimes it is in a harsh environment of high temperature and high humidity, which may easily cause the LED lamp to be damaged, and open or short the LED lamp.
  • the LED lamp has an open or short circuit fault, not only the damaged LED lamp itself cannot be normally lit, but also an undesired current path may be formed, causing an unselected LED lamp to be abnormally lit, thereby forming an abnormal pixel bright spot.
  • This abnormal lighting phenomenon causes abnormal images.
  • the area of LED display devices is getting larger and larger, the number of LED lights is increasing, and the probability of open and short circuits is greatly increased. Once open and short circuit problems occur, the image quality will be greatly affected.
  • An object of the present invention is to provide an LED display device and a driving method thereof, in which a voltage limiting module is used to improve image quality and reduce power consumption when an open-short fault occurs in the LED lamp.
  • an LED display device including: an LED array including a plurality of LED lamps arranged in rows and columns; a row driving module including a plurality of output terminals respectively connected with the plurality of LED lamps; The corresponding rows of LED lights are connected to provide a power supply voltage; multiple constant current sources control the current flowing through the plurality of LED lights according to the display data when the corresponding row LED lights of the plurality of LED lights obtain the supply voltage.
  • the plurality of voltage-limiting modules disconnect the current paths via the short-circuited LED lamp and the open-circuited LED lamp when the plurality of LED lamps have an open-short fault, so as to avoid abnormal lighting of the plurality of LED lamps.
  • the plurality of constant current sources control at least one of a current value and a duty ratio of the driving current according to the display data.
  • the multiple output terminals of the row driving module are respectively connected to the anodes of the corresponding row LED lamps of the plurality of LED lamps, and the plurality of constant current sources are respectively connected via the corresponding ones of the plurality of voltage limiting modules.
  • the voltage limiting module is connected to a cathode of a corresponding row of LED lamps of the plurality of LED lamps.
  • the plurality of voltage limiting modules compare the port voltages of the plurality of constant current sources with a reference voltage, and determine whether the plurality of LED lamps have open-short faults according to the comparison results.
  • the port voltages of the plurality of constant current sources in a non-working state, a normal working state, and an abnormal working state are a first voltage, a second voltage, and a third voltage, respectively, and the reference voltage is less than the first voltage. And the second voltage, and greater than the third voltage.
  • a driving current flows through a first current path, and when a corresponding row of the plurality of LED lamps obtains a power supply voltage, the first current path
  • the respective constant current sources of the plurality of constant current sources are respectively reached via the corresponding row LED lights.
  • the driving current flows in the abnormal working state of the plurality of constant current sources via a second current path, wherein when the corresponding row of the plurality of LED lamps obtains a power supply voltage, the second current path
  • the at least one LED lamp in the row where the short-circuit LED lamp is located and the at least one LED lamp in the row where the open-circuit LED lamp is located respectively reach the corresponding constant current source of the plurality of constant current sources.
  • the second current path is disconnected after being momentarily turned on.
  • the first voltage is approximately equal to the power supply voltage
  • the second voltage is approximately equal to the power supply voltage minus the turn-on voltage drop of a single LED lamp
  • the third voltage is approximately equal to the power supply voltage minus The voltage drop of two LED lamps connected in series.
  • the plurality of voltage-limiting modules each include a comparator, and a non-inverting input terminal and an inverting input terminal of the comparator respectively receive a voltage sampling signal of the port voltage and the reference voltage, and an output terminal provides switching control.
  • Signal a voltage sampling signal of the port voltage and the reference voltage
  • an output terminal provides switching control.
  • Signal a switch tube
  • the control terminal of the switch tube is connected to the output terminal of the comparator to receive the switch control signal
  • the first current terminal and the second current terminal of the switch tube are respectively connected to the corresponding columns of LED lights.
  • High-voltage port of the cathode and corresponding constant current source are examples of the cathode and corresponding constant current source.
  • a non-inverting input terminal of the comparator is connected to a first current terminal of the switch tube to obtain the voltage sampling signal.
  • a plurality of capacitors are further included, and the plurality of capacitors are respectively connected between the non-inverting input terminal of the comparator in the corresponding voltage limiting module and the ground, and are configured to store the voltage sampling signal in a frame period.
  • the plurality of capacitances are parasitic capacitances or additional capacitive devices.
  • a driving method for an LED display device includes an LED array, the LED array includes a plurality of LED lamps arranged in rows and columns, and the method includes: Line scanning is performed in each frame period; in each line period, a power supply voltage is provided to the corresponding row LED lights of the plurality of LED lights respectively; and the corresponding columns in the plurality of LED lights are controlled to flow through according to the display data.
  • a driving current of the LED lamp thereby achieving brightness corresponding to the display data; and disconnecting a current path via the short-circuit LED lamp and the open-circuit LED lamp when the plurality of LED lamps have an open-short fault, so as to avoid the plurality of LEDs The lamp lights abnormally.
  • At least one of a current value and a duty ratio of the driving current is controlled according to the display data.
  • the method further includes: using a plurality of constant current sources to separately control the driving currents of the corresponding rows of LED lamps in the plurality of LED lamps; According to the comparison, it is determined whether an open-short fault occurs in the plurality of LED lamps according to a comparison result.
  • the port voltages of the plurality of constant current sources in a non-working state, a normal working state, and an abnormal working state are a first voltage, a second voltage, and a third voltage, respectively, and the reference voltage is less than the first voltage. And the second voltage, and greater than the third voltage.
  • a driving current flows through a first current path, and when a corresponding row of the plurality of LED lamps obtains a power supply voltage, the first current path
  • the respective constant current sources of the plurality of constant current sources are respectively reached via the corresponding row LED lights.
  • the driving current flows in the abnormal working state of the plurality of constant current sources via a second current path, wherein when the corresponding row of the plurality of LED lamps obtains a power supply voltage, the second current path
  • the at least one LED lamp in the row where the short-circuit LED lamp is located and the at least one LED lamp in the row where the open-circuit LED lamp is located respectively reach the corresponding constant current source of the plurality of constant current sources.
  • the second current path is disconnected after being momentarily turned on.
  • the first voltage is approximately equal to the power supply voltage
  • the second voltage is approximately equal to the power supply voltage minus the turn-on voltage drop of a single LED lamp
  • the third voltage is approximately equal to the power supply voltage minus The voltage drop of two LED lamps connected in series.
  • the capacitor is used to store the voltage sampling signal in a frame period.
  • a voltage limiting module is provided between a plurality of constant current sources and corresponding rows of LED lights. And the current path of the open LED lamp to avoid abnormal lighting of the LED lamp, thereby improving image quality and reducing power consumption.
  • the voltage limiting module detects an open-short fault according to the port voltage of the constant current source.
  • the voltage-limiting module disconnects the connection between the constant current source and the corresponding column of LED lights, thereby disconnecting the current path through the short-circuited LED and the open-ended LED.
  • the voltage-limiting module does not need a complicated detection circuit and a logic circuit, and thus can further reduce the circuit cost.
  • FIG. 1 shows a schematic circuit diagram of an LED display device according to the related art.
  • FIG. 2 illustrates a current path when the LED lamp in the LED display device of FIG. 1 has an open-short fault.
  • FIG. 3 shows a schematic circuit diagram of an LED display device according to an embodiment of the present invention.
  • FIG. 4 illustrates a current path when the LED lamp in FIG. 3 has an open-short fault.
  • FIG. 5 is a schematic circuit diagram of a row driving module in the LED display device of FIG. 3.
  • FIG. 6 is a schematic circuit diagram of a voltage limiting module in the LED display device of FIG. 3.
  • open-short means that in the LED array of the LED display device, at least one LED lamp is open-circuit damaged and at least another LED lamp is short-circuit damaged.
  • FIG. 1 shows a schematic circuit diagram of an LED display device according to the related art.
  • the LED display device uses a common anode solution.
  • the LED display device 100 includes an LED array 110, a row driving module 120, and a plurality of constant current sources 130.
  • the LED array 110 includes a plurality of pixel units arranged in rows and columns, for example, forming a pixel array.
  • each pixel unit includes a monochrome LED lamp.
  • each pixel unit includes three LED lights, which are red, green, and blue LED lights, respectively.
  • the anodes of the LED lamps in each row in the LED array 110 are connected to each other.
  • a plurality of output terminals of the row driving module 120 are respectively connected to anodes of corresponding row LED lamps in the LED array, thereby providing a power supply voltage VCC.
  • the cathodes of the columns of LEDs in the LED array 110 are connected to each other, and then connected to the ground via the corresponding constant current source 130.
  • the row driving module 120 selectively supplies the power supply voltage VCC to the anodes of the LED lamps of the corresponding rows in a row period according to the scan signals.
  • the constant current source 130 When the LED lamps in the selected row are connected to the power supply voltage VCC, the constant current source 130 generates a driving current, and the current value and the duty cycle of the driving current can be changed according to the display data, thereby jointly determining the brightness of the LED lamps. Only one scanning signal is valid at any time, which determines that at any time only the LED lights of the corresponding row of the scanning signal receive the power supply voltage VCC and turn on, and the remaining rows of LED lights are off.
  • the constant current source provides a constant current to the selected LED lights according to the display data. Therefore, the brightness values of the plurality of LED lights in the pixel array correspond to the grayscale values of the plurality of pixel units in the frame picture, thereby realizing the display of the frame picture.
  • FIG. 2 illustrates a current path when the LED lamp in the LED display device of FIG. 1 has an open-short fault.
  • the figure shows an equivalent circuit diagram when the LED lamps in the x-th row and the y-column are short-circuited.
  • a plurality of LED lamps in a pixel array are scanned in a row.
  • the row driving module 120 supplies power to the plurality of LED lamps in the (x + m) row
  • the LED lamps in the (x + m) row (y + n) column receive the power supply voltage VCC.
  • a first current path is formed. That is, the LED lamp is turned on to form a current path through the LED lamp in the (x + m) th row (y + n) th column.
  • the LED lights in the (x + m) row are normally lit, and the LED lights in the other rows are normally turned off.
  • a second current path is formed. That is, the LED lamp is turned off to form a current path through the LED lamp in the x-th row and the y-th column and the LED lamp in the x-th row (y + n).
  • the LED lights in the (x + m) th row except for the yth and (y + n) th rows are normally lit, however, the LEDs in the (x + m) th and yth rows and the xth (y +) th row n) The LEDs in the column are abnormally lit.
  • the LED lamps in the (x + m) th row (y + n) th column are open, the above-mentioned first current path is blocked. If at this time the lamp in the same row as the LED lamp in the xth row and y column need not be lit, that is, the LED lamp in the (x + m) th row and y column shown in FIG.
  • the supply voltage VCC of the LED lamps in the (x + m) row is 5V, and the LED lamps in the xth row and y column are short-circuited, then there will be LED lamps passing the (x + m) th row and y column and the xth row and y column Lamp, the path from the x-th row (y + n) LED lamp to the constant current source to ground, that is, the second current path shown in Figure 2, this current path will make the (x + m) row y-column The LED light and the LED light in the xth row (y + n) column are abnormally lit.
  • FIG. 3 shows a schematic circuit diagram of an LED display device according to an embodiment of the present invention.
  • the LED display device 200 includes an LED array 110, a row driving module 120, a plurality of constant current sources 130, and a plurality of voltage limiting modules 140.
  • the LED array 110 includes a plurality of pixel units arranged in rows and columns, for example, forming a pixel array.
  • each pixel unit includes a monochrome LED lamp.
  • each pixel unit includes three LED lights, which are red, green, and blue LED lights, respectively.
  • the anodes of the LED lamps in each row in the LED array 110 are connected to each other.
  • a plurality of output terminals of the row driving module 120 are respectively connected to anodes of corresponding row LED lamps in the LED array, thereby providing a power supply voltage VCC.
  • the cathodes of the columns of LEDs in the LED array 110 are connected to each other, and then connected to the ground through the corresponding voltage limiting module 140 and the constant current source 130.
  • the power supply voltage VCC is, for example, a voltage of 5V, and the turn-on voltage drop Von of each LED lamp is about 2 to 3V.
  • the plurality of constant current sources 130 are connected to the cathodes of the plurality of LED lamps in the corresponding row via the corresponding voltage limiting module 140, so as to provide a constant current when the LED lamps are gated.
  • the magnitude of the constant current provided by the constant current source 130 and the on-time duty cycle together determine the brightness of the LED lamp.
  • the row driving module 120 selectively supplies the power supply voltage VCC to the anode of the LED lamp of the corresponding row in a row period according to one of the scan signals SCAN1 to SCANn.
  • the constant current source 130 When the LED lamps in the selected row are connected to the power supply voltage VCC, the constant current source 130 generates a driving current, and the current value and the duty cycle of the driving current can be changed according to the display data, thereby jointly determining the brightness of the LED lamps. Only one scanning signal is valid at any time, which determines that at any time only the LED lights of the corresponding row of the scanning signal receive the power supply voltage VCC and turn on, and the remaining rows of LED lights are off.
  • the constant current source provides a constant current to the selected LED lights according to the display data. Therefore, the brightness values of the plurality of LED lights in the pixel array correspond to the grayscale values of the plurality of pixel units in the frame picture, thereby realizing the display of the frame picture.
  • the LED display device 200 includes a voltage limiting module 140.
  • the voltage limiting module 140 detects a port voltage of the constant current source 130. When the port voltage is lower than the set reference voltage Vos, the voltage limiting module 140 controls the constant current source 130 to be turned off, thereby disconnecting the current path of the LED lamps in the corresponding column.
  • the LED display device 200 can prevent abnormal lighting of a plurality of LED lights even when the LED lights in the LED display device have an open-short fault, thereby improving the image quality.
  • FIG. 4 illustrates a current path when the LED lamp in FIG. 3 has an open-short fault.
  • the voltage limiting module 140 detects the port voltage of the constant current source 130.
  • the port voltage of the constant current source 130 is a first voltage V1 when it is not in operation, and a second voltage V2 when it is in normal operation.
  • the first voltage V1 is higher than the second voltage V2.
  • the first voltage V1 the supply voltage VCC
  • the second voltage V2 the supply voltage VCC-the on-voltage drop Von of the LED lamp.
  • the LED lamps in the LED array open and short, a current path is formed via the row of the shorted LED lamp and the column of the open LED lamp.
  • the range of setting the reference voltage Vos is lower than the port voltages V1 and V2 during normal operation and higher than the port voltage V3 during open and short circuits.
  • the power supply voltage VCC 5V
  • the on-voltage drop of the LED lamp Von 2V.
  • the reference voltage Vos can be set to be slightly lower than 3V.
  • the short-circuited LED lamp is located in row x
  • the open-circuited LED lamp is located in column (y + n).
  • the LED lamp in row x and column y is short-circuited
  • the LED lamps are spaced by n rows and m columns of lamps, that is, the (x + m) th row (y + n) th column of LED lamps is open.
  • the LED lights in that line receive the power supply voltage VCC.
  • the LED lamp in the (x + m) th row (y + n) column does not open, the LED lamp is turned on.
  • the second voltage V2 is higher than the reference voltage Vos, the constant current source 130 works normally, and the constant current is output to pull down, thereby forming a first current path through the LED lamp.
  • the LED lamp is turned off.
  • the third voltage V3 is lower than the reference voltage Vos, and the constant current source 130 is turned off, thereby disconnecting the second current path through the current path of the row where the short-circuit LED lamp is located and the column where the open-circuit LED lamp is located.
  • the short-circuited LED lamp is located in the x-th row
  • the open-circuited LED lamp is located in the (y + n) -th column.
  • the LED lamps are separated by n rows and m columns of lamps, that is, the (x + m) th row (y + n) column of LED lamps are open.
  • the equivalent circuit is shown in FIG. 4.
  • the capacitance C represents a parasitic capacitance widely present in the LED display device.
  • the capacitor C is an additional capacitive device connected between the input terminal of the voltage limiting module and the ground. As described below, the capacitor C is used to store the port voltage of the constant current source 130 in a frame period.
  • the row driving module 120 will control the power supply terminal to sequentially supply the power supply voltage VCC to the rows of LED lamps in the LED array 120, that is, the rows of LED lamps will light up in sequence.
  • V2 3V.
  • the constant current source 130 in the column will be immediately turned off, thereby disconnecting the second current path. After being disconnected, the port voltage of the constant current source 130 in the column will be maintained at 1V, and the next time when the LED lights in the column are normally lit, the voltage is restored to 3V.
  • the voltage limiting module 140 detects a constant current at this time
  • the source port voltage 1V, which is lower than the set reference voltage, will not turn on the constant current source, so a second current path cannot be formed until the next time the LED lights in the column are normally lit, the voltage is restored to 3V.
  • the LED display device 200 can prevent abnormal lighting of a plurality of LED lights even when the LED lights in the LED display device have an open-short fault, thereby improving the image quality.
  • FIG. 5 is a schematic circuit diagram of a row driving module in the LED display device of FIG. 3.
  • the row driving module 120 includes a plurality of switching tubes 121, such as a P-type metal-oxide-semiconductor field-effect transistor (PMOSFET).
  • the source is connected to the first terminal and connected to the supply voltage VCC.
  • the drain is the second terminal. Connected to the anodes of the corresponding rows of LEDs in the LED array 110.
  • PMOSFET P-type metal-oxide-semiconductor field-effect transistor
  • the driving module 120 selectively gates the plurality of switching tubes 121 according to one of the scanning signals SCAN1 to SCANn, and supplies the power supply voltage VCC to the anodes of the LED lamps in the corresponding rows via the selected switching tubes 121.
  • FIG. 6 is a schematic circuit diagram of a voltage limiting module in the LED display device of FIG. 3.
  • the voltage limiting module 140 can be implemented in various ways. As shown in FIG. 6, the voltage limiting module 140 includes a comparator 141 and a switch 142.
  • the switching tube 142 is, for example, an N-type metal oxide semiconductor field effect transistor (NMOSFET).
  • NMOSFET N-type metal oxide semiconductor field effect transistor
  • the switching tube 142 in the voltage limiting module 140 is connected in series with the constant current source 130.
  • the source of the switching tube 142 is connected to the high-voltage port of the constant current source 130, and the drain is connected to the cathode of the corresponding LED lamp in the LED array 110.
  • the non-inverting input terminal of the comparator 141 receives a voltage sampling signal Vs for characterizing the port voltage of the constant current source 130, the inverting input terminal receives the reference voltage Vos, and the output terminal is connected to the control terminal of the switching tube 142 to provide a switching control signal Vg.
  • the non-inverting input terminal of the comparator 141 is connected to the drain of the switching tube 142, so that the drain voltage Vd of the switching tube 142 is used as the port voltage of the constant current source 130.
  • the comparator 141 compares the port voltage of the constant current source 130 with a reference voltage Vos, thereby generating a switching control signal Vg.
  • Vd> Vos the output of the comparator 141 is 1, and the switch 142 is turned on.
  • Vd ⁇ Vos the output of the comparator 141 is 0, and the switch 142 is turned off.
  • the implementation of the above-mentioned voltage limiting module 140 is merely an example, and the switch 142 may be newly added or an existing design of multiplexing a constant current source port, and the purpose thereof is to controllably turn off.
  • the voltage-limiting module 140 adopts a circuit design of a comparator and a switch tube, which is only one implementation means of the voltage-limiting module.
  • the voltage limiting module 140 can be any circuit design, as long as it turns off the constant current source 130 within a certain set voltage range.
  • the fundamental method of the present invention is to propose a new LED display device and driving method, which solves the problem of image errors caused by the short and open of LED lamps in the prior art, and increases the reliability of the display system. And improve display performance.

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  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
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Abstract

一种LED显示装置(100,200)及其驱动方法。该LED显示装置(100,200)包括：LED阵列(110)，包括排列成行和列的多个LED灯；行驱动模块，包括多个输出端，分别与所述多个LED灯中的相应行LED灯相连接，从而提供供电电压；多个恒流源(130)，在多个LED灯中的相应行LED灯获得供电电压时，根据显示数据控制流经多个LED灯中的相应列LED灯的驱动电流，从而实现与显示数据相对应的亮度；以及多个限压模块(140)，分别连接在多个LED灯中的相应列LED灯和相应恒流源(130)之间，其中，多个限压模块(140)在多个LED灯出现开短路故障时断开经由短路LED灯和开路LED灯的电流路径，以避免多个LED灯的异常点亮。LED显示装置(100,200)可以在LED灯出现开短路故障时改善图像质量和降低功耗。

Description

LED显示装置及其驱动方法
本申请要求了2018年7月11日提交的、申请号为201810758390.7、发明名称为“LED显示装置及其驱动方法”的中国专利申请的优先权，并且通过参照上述中国发明申请的全部说明书、权利要求、附图和摘要的方式，将其引用于本申请。
技术领域
本发明涉及LED显示技术，更具体地，涉及LED显示装置及其驱动方法。
背景技术
LED显示装置在显示领域已经获得了广泛的应用。LED显示装置具有以下方面的优越性：高亮度、宽可视角度、丰富的色彩以及可定制的屏幕形状，广泛应用于工业、交通、商业广告、信息发布、体育比赛等各个领域。
在LED显示装置中使用的像素元件是LED灯，其中，多个LED灯组成像素阵列。在工作期间，例如，LED显示装置按行扫描，分别将恒流源与选择的LED串联连接，从而点亮相应行的LED。采用电流控制法和导通时间控制法来控制选择的LED的亮度，从而实现多级灰度。在电流控制法中，通过调节LED中流过的电流大小来控制其亮度。导通时间控制法是在恒流驱动的情形下，通过改变占空比来控制LED的亮度。
然而，在实际使用环境中，LED显示装置常常需要长时间工作，有时还会处于高温、高湿的恶劣环境中，容易造成LED灯损坏，形成LED灯开路或者短路。在LED灯发生开短路故障时，不仅损坏的LED灯本身无法正常点亮，而且可能形成不期望的电流路径，导致未选择的LED灯异常点亮，从而形成异常像素亮点。这种异常点亮现象导致图像异常。随着LED显示装置面积越来越大，LED灯的数量越来越多，出现开短路的概率大大增加，一旦出现开短路问题，将大大影响图像质量。
因此，期望进一步改进LED显示装置从而在LED灯出现开短路时仍然可以改善图像质量。
发明内容
本发明的目的是提供一种LED显示装置及其驱动方法，其中，采用限压模块在LED灯出现开短路故障时改善图像质量和降低功耗。
根据本发明的一方面，提供一种LED显示装置，包括：LED阵列，包括排列成行和列的多个LED灯；行驱动模块，包括多个输出端，分别与所述多个LED灯中的相应行LED灯相连接，从而提供供电电压；多个恒流源，在所述多个LED灯中的相应行LED灯获得供电电压时，根据显示数据控制流经所述多个LED灯中的相应列LED灯的驱动电流，从而实现与显示数据相对应的亮度；以及多个限压模块，分别连接在所述多个LED灯中的相应列LED灯和相应恒流源之间，其中，所述多个限压模块在所述多个LED灯出现开短路故障时断开经由短路LED灯和开路LED灯的电流路径，以避免所述多个LED灯的异常点亮。
优选地，所述多个恒流源根据所述显示数据控制所述驱动电流的电流值和占空比至少之一。
优选地，所述行驱动模块的多个输出端分别与所述多个LED灯的相应行LED灯的阳极相连接，所述多个恒流源，分别经由所述多个限压模块的相应限压模块连接至所述多个LED灯的相应列LED灯的阴极。
优选地，所述多个限压模块将所述多个恒流源的端口电压与参考电压相比较，根据比较结果判断所述多个LED灯是否出现开短路故障。
优选地，所述多个恒流源在未工作状态、正常工作状态、异常工作状态下的端口电压分别为第一电压、第二电压和第三电压，所述参考电压小于所述第一电压和所述第二电压，并且大于所述第三电压。
优选地，所述多个恒流源的正常工作状态中驱动电流经由第一电流路径流动，其中，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第一电流路径经由所述相应行LED灯分别到达所述多个恒流源中的相应恒流源。
优选地，所述多个恒流源的异常工作状态中驱动电流经由第二电流路径流动，其中，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第二电流路径经由短路LED灯所在行的至少一个LED灯、开路LED灯所在行的至少一个LED灯，分别到达所述多个恒流源中的相应恒流源。
优选地，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第二电流路径在瞬时导通之后断开。
优选地，所述第一电压大致等于所述供电电压，所述第二电压大致等于所述供电电压减去单个LED灯的导通压降，所述第三电压大致等于所述供电电压减去两个LED灯串联的导通压降。
优选地，所述多个限压模块分别包括：比较器，所述比较器的同相输入端和反相输入端分别接收所述端口电压的电压采样信号和所述参考电压，输出端提供开关控制信号；以及开关管，所述开关管的控制端连接至所述比较器的输出端以接收开关控制信号，所述开关管的第一电流端和第二电流端分别连接至相应列LED灯的阴极和相应恒流源的高压端口。
优选地，所述比较器的同相输入端连接至所述开关管的第一电流端，以获得所述电压采样信号。
优选地，还包括多个电容，所述多个电容分别连接在相应限压模块中的比较器的同相输入端和地之间，用于在帧周期中存储所述电压采样信号。
优选地，所述多个电容为寄生电容或附加电容器件。
根据本发明的另一方面，提供一种用于LED显示装置的驱动方法，所述LED显示装置包括LED阵列，所述LED阵列包括排列成行和列的多个LED灯，所述方法包括：在每个帧周期中进行行扫描；在每个行周期中，分别向所述多个LED灯中的相应行LED灯提供供电电压；根据显示数据控制流经所述多个LED灯中的相应列LED灯的驱动电流，从而实现与显示数据相对应的亮度；以及在所述多个LED灯出现开短路故障时断开经由短路LED灯和开路LED灯的电流路径，以避免所述多个LED灯的异常点亮。
优选地，在控制驱动电流的步骤中，根据所述显示数据控制所述驱动电流的电流值和占空比至少之一。
优选地，还包括：采用多个恒流源分别控制所述多个LED灯中的相应列LED灯的驱动电流；以及将所述多个恒流源的端口电压的电压采样信号与参考电压相比较，根据比较结果判断所述多个LED灯是否出现开短路故障。
优选地，所述多个恒流源在未工作状态、正常工作状态、异常工作状态下的端口电压分别为第一电压、第二电压和第三电压，所述参考电压小于所述第一电压和所述第二电压，并且大于所述第三电压。
优选地，所述多个恒流源的正常工作状态中驱动电流经由第一电流路径流动，其中，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第一电流路径经由所述相应行LED灯分别到达所述多个恒流源中的相应恒流源。
优选地，所述多个恒流源的异常工作状态中驱动电流经由第二电流路径流动，其中，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第二电流路径经由短路LED灯所在行的至少一个LED灯、开路LED灯所在行的至少一个LED灯，分别到达 所述多个恒流源中的相应恒流源。
优选地，在行周期中，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第二电流路径在瞬时导通之后断开。
优选地，所述第一电压大致等于所述供电电压，所述第二电压大致等于所述供电电压减去单个LED灯的导通压降，所述第三电压大致等于所述供电电压减去两个LED灯串联的导通压降。
优选地，采用电容，在帧周期中存储所述电压采样信号。
根据本发明实施例的LED显示装置及其驱动方法，在多个恒流源和相应列LED灯之间设置限压模块，该限压模块在LED灯出现开短路故障时断开经由短路LED灯和开路LED灯的电流路径，以避免LED灯的异常点亮，从而改善图像质量和降低功耗。
在优选的实施例中，限压模块根据恒流源的端口电压检测开短路故障。在端口电压低于设定的参考电压时，限压模块断开恒流源与相应列LED灯之间的连接，从而断开经由短路LED灯和开路LED灯的电流路径。该限压模块无需复杂的检测电路和逻辑电路，因而可以进一步降低电路成本。
附图说明
通过以下参照附图对本发明实施例的描述，本发明的上述以及其他目的、特征和优点将更为清楚，在附图中：
图1示出根据现有技术的LED显示装置的示意性电路图。
图2示出图1的LED显示装置中LED灯发生开短路故障时的电流路径。
图3示出根据本发明实施例的LED显示装置的示意性电路图。
图4示出图3的LED显示装置中LED灯发生开短路故障时的电流路径。
图5示出图3的LED显示装置中行驱动模块的示意性电路图。
图6示出图3的LED显示装置中限压模块的示意性电路图。
具体实施方式
以下将参照附图更详细地描述本发明的各种实施例。在各个附图中，相同的元件采用相同或类似的附图标记来表示。为了清楚起见，附图中的各个部分没有按比例绘制。
在本申请中，术语“开短路”表示在LED显示装置的LED阵列中，同时存在着至 少一个LED灯发生开路损坏且至少另一个LED灯发生短路损坏的情形。
图1示出根据现有技术的LED显示装置的示意性电路图。在该实施例中，LED显示装置采用共阳极的解决方案。
如图所示，该LED显示装置100包括LED阵列110、行驱动模块120、多个恒流源130。LED阵列110包括按行和列排列的多个像素单元，例如形成像素阵列。在单色的LED显示装置中，每个像素单元包括一个单色LED灯。在彩色的LED显示装置中，每个像素单元包括三个LED灯，分别为红、绿、蓝色LED灯。LED阵列110中的各行LED灯的阳极彼此连接。行驱动模块120的多个输出端分别连接至所述LED阵列中的相应行LED灯的阳极，从而提供供电电压VCC。LED阵列110中的各列LED的阴极彼此连接，然后经由相应的恒流源130连接至地。
在工作期间，在每个帧周期中按行扫描。行驱动模块120根据扫描信号，在行周期中选择性地将供电电压VCC提供给相应行的LED灯的阳极。在选择行的LED灯连接至供电电压VCC时，恒流源130产生驱动电流，并且该驱动电流的电流值和占空比可以根据显示数据而改变，从而共同决定LED灯的亮度。在任何时刻只有一个扫描信号是有效的，这就决定了在任何时刻只有该扫描信号相应行的LED灯接收供电电压VCC而点亮，其余各行LED灯则是熄灭的。
在帧周期中，像素阵列中的多个LED灯按行扫描，恒流源按照显示数据向选择的LED灯提供恒定电流。因此，像素阵列中的多个LED灯的亮度值与帧画面中的多个像素单元的灰阶值相对应，从而实现帧画面的显示。
图2示出图1的LED显示装置中LED灯发生开短路故障时的电流路径。在图中示出第x行y列的LED灯短路时的等效电路图。
在图2所示的LED显示装置100中，像素阵列中的多个LED灯按行扫描。在行驱动模块120向第(x+m)行的多个LED灯供电时，第(x+m)行(y+n)列的LED灯接收供电电压VCC。
在第(x+m)行(y+n)列的LED灯没有开路的情形下，形成第1电流路径。即，该LED灯导通，形成经由第(x+m)行(y+n)列的LED灯的电流路径。第(x+m)行的LED灯均正常点亮，并且，其余行的LED灯均正常熄灭。
在第(x+m)行(y+n)列的LED灯出现开路的情形下，形成第2电流路径。即，该LED灯断开，形成经由第x行y列的LED灯和第x行(y+n)列的LED灯的电流路径。第(x+m)行中除第y列和第(y+n)列以外的LED灯均正常点亮，然而，第(x+m)行y列 的LED灯和第x行(y+n)列的LED灯异常点亮。
具体地，在第(x+m)行(y+n)列的LED灯出现开路的情形下，上述的第1电流路径不通。若此时该选中行上与第x行y列的LED灯同一列的灯不需要点亮，即图2所示的第(x+m)行y列的LED灯不需要点亮，由于第(x+m)行的LED灯的供电电压VCC为5V、第x行y列的LED灯短路，那么将存在通过第(x+m)行y列的LED灯、第x行y列的LED灯、第x行(y+n)列的LED灯到恒流源到地的路径，即图2所示的第2电流路径，该电流路径将会使第(x+m)行y列的LED灯和第x行(y+n)列的LED灯异常点亮。
图3示出根据本发明实施例的LED显示装置的示意性电路图。
如图所示，该LED显示装置200包括LED阵列110、行驱动模块120、多个恒流源130、多个限压模块140。LED阵列110包括按行和列排列的多个像素单元，例如形成像素阵列。在单色的LED显示装置中，每个像素单元包括一个单色LED灯。在彩色的LED显示装置中，每个像素单元包括三个LED灯，分别为红、绿、蓝色LED灯。LED阵列110中的各行LED灯的阳极彼此连接。行驱动模块120的多个输出端分别连接至所述LED阵列中的相应行LED灯的阳极，从而提供供电电压VCC。LED阵列110中的各列LED的阴极彼此连接，然后经由相应的限压模块140和恒流源130连接至地。
在该实施例中，供电电压VCC例如为5V的电压，每个LED灯的导通压降Von约为2～3V。
多个恒流源130经由相应的限压模块140连接到相应列的多个LED灯的阴极，从而在LED灯选通时提供恒定电流。例如，恒流源130提供的恒定电流的大小和开启时间占空比共同决定LED灯的亮度。
在工作期间，在每个帧周期中按行扫描。行驱动模块120根据扫描信号SCAN1至SCANn之一，在行周期中选择性地将供电电压VCC提供给相应行的LED灯的阳极。在选择行的LED灯连接至供电电压VCC时，恒流源130产生驱动电流，并且该驱动电流的电流值和占空比可以根据显示数据而改变，从而共同决定LED灯的亮度。在任何时刻只有一个扫描信号是有效的，这就决定了在任何时刻只有该扫描信号相应行的LED灯接收供电电压VCC而点亮，其余各行LED灯则是熄灭的。
在帧周期中，像素阵列中的多个LED灯按行扫描，恒流源按照显示数据向选择的LED灯提供恒定电流。因此，像素阵列中的多个LED灯的亮度值与帧画面中的多个像素单元的灰阶值相对应，从而实现帧画面的显示。
与图1所示的现有技术的LED显示装置100不同，根据该实施例的LED显示装置200包括限压模块140。限压模块140检测恒流源130的端口电压。在端口电压低于设定的参考电压Vos时，限压模块140控制恒流源130关断，从而断开相应列的LED灯的电流路径。该LED显示装置200即使在LED显示装置中的LED灯出现开短路故障时，也可以避免多个LED灯的异常点亮，从而改善图像质量。
图4示出图3的LED显示装置中LED灯发生开短路故障时的电流路径。
如上所述，在该实施例的LED显示装置200中，限压模块140检测恒流源130的端口电压。恒流源130的端口电压在未工作时为第一电压V1，在正常工作时为第二电压V2，第一电压V1高于第二电压V2。例如，第一电压V1＝供电电压VCC，第二电压V2＝供电电压VCC-LED灯的导通压降Von。
在LED阵列中的LED灯出现开短路时，形成经由短路LED灯所在行和开路LED灯所在列的电流路径，在开路LED灯所在列的恒流源130上，恒流源130的端口电压为第三电压V3，该第三电压V3为异常电压，第三电压V3＝供电电压VCC-LED灯的导通压降Von*2。
在该实施例中，设置参考电压Vos的范围为低于正常工作时的端口电压V1和V2、高于开短路时的端口电压V3。例如，假设供电电压VCC＝5V，LED灯的导通压降Von＝2V，在LED灯正常点亮时，恒流源130的端口电压为第二电压V2＝3V，在LED灯出现开短路时，恒流源130的端口电压为第三电压V3＝1V。此时，参考电压Vos可设定为略低于3V。
例如，在图3所示的LED显示装置中，假设短路LED灯所在行为第x行，开路LED灯所在列为第(y+n)列，例如，第x行y列的LED灯短路，与该LED灯间隔n行m列的灯，即第(x+m)行(y+n)列的LED灯开路。在第(x+m)行线选通时，该行的LED灯接收电源电压VCC。
如果第(x+m)行(y+n)列的LED灯没有发生开路，则该LED灯导通。此时，限压模块140检测到相应列的恒流源130的端口电压为第二电压V2＝供电电压VCC-LED灯的导通压降Von＝3V。该第二电压V2高于参考电压Vos，恒流源130正常工作，输出下拉恒流，从而形成经由该LED灯的第1电流路径。
如果第(x+m)行(y+n)列的LED灯发生开路，则该LED灯断开。此时，限压模块140检测到相应列的恒流源130的端口电压为第三电压V3＝供电电压VCC-LED灯的导通压降Von*2＝1V。该第三电压V3低于参考电压Vos，恒流源130关断，从而断开 经由短路LED灯所在行和开路LED灯所在列的电流路径的第2电流路径。
下面结合LED显示装置200的帧周期，描述所述限压模块140的工作过程。在图3所示的LED显示装置200中，假设短路LED灯所在行为第x行，开路LED灯所在列为第(y+n)列，例如，第x行y列的LED灯短路，与该LED灯间隔n行m列的灯，即第(x+m)行(y+n)列的LED灯开路，等效电路如图4所示。
在该实施例中，电容C表示LED显示装置中广泛存在的寄生电容。在替代的实施例中，电容C为附加电容器件，连接在限压模块的输入端和地之间。如下文所述，电容C用于在帧周期中存储恒流源130的端口电压。
在每个帧周期中，行驱动模块120将会控制电源端依次向LED阵列120中的各行LED灯提供供电电压VCC，即各行LED灯将会依次点亮。
在开路LED灯所在行点亮之前，当开路LED灯所在列的有LED灯点亮时，该列的恒流源130的端口电压为第二电压V2＝3V。当该列LED灯的点亮时间结束、对应的恒流源被关断时，由于寄生电容的存在，该列的恒流源130的端口电压将继续维持在3V。之后，若该列的LED灯不需要点亮，该列的恒流源130的端口电压将一直保持为3V。
当开路第(x+m)行(y+n)列的LED灯所在行点亮、即第(x+m)行线选通且接收电源电压VCC时，若第(x+m)行(y+n)列的LED灯需要点亮，此时存在经由第(x+m)行y列的LED灯、第x行y列的LED灯、第x行(y+n)列的LED灯到恒流源到地的瞬时路径，将会导致第(y+n)列的恒流源端口电压瞬时下降至1V。此时，限压模块140启动工作，由于恒流源130的端口电压低于设定的参考电压Vos，将会立刻关断该列的恒流源130，从而断开第2电流路径。在断开后，该列的恒流源130的端口电压将保持在1V，直到下一次该列有LED灯正常点亮时，该电压恢复到3V。
在一个帧周期内，开路第(x+m)行(y+n)列的LED灯所在行点亮前，当与该开路LED灯同一列的灯中没有LED灯点亮、而只有该开路LED灯曾经点亮过时，根据之前的分析，此时该列的恒流源130的端口电压为1V；
当开路第(x+m)行(y+n)列的LED灯所在行点亮、即第(x+m)行线选通且接收电源电压VCC时，此时限压模块140检测到恒流源端口电压＝1V，低于设定的参考电压，将不会打开恒流源，因此无法形成第2电流路径，直到下一次该列有LED灯正常点亮时，该电压恢复到3V。
因此，该LED显示装置200即使在LED显示装置中的LED灯出现开短路故障时，也可以避免多个LED灯的异常点亮，从而改善图像质量。
图5示出图3的LED显示装置中行驱动模块的示意性电路图。
在LED显示装置200中，行驱动模块120包括多个开关管121，例如P型金属氧化物半导体场效应晶体管(PMOSFET)，源极为第一端，连接至供电电压VCC，漏极为第二端，连接至LED阵列110中相应行的LED的阳极。
在工作期间，驱动模块120根据扫描信号SCAN1至SCANn之一，选择性地选通多个开关管121，将供电电压VCC经由选择的开关管121提供给相应行的LED灯的阳极。
图6示出图3的LED显示装置中限压模块的示意性电路图。
在LED显示装置200中，限压模块140可以有多种实现方式。如图6所示，限压模块140包含比较器141和开关管142。开关管142例如是N型金属氧化物半导体场效应晶体管(NMOSFET)。
限压模块140中的开关管142与恒流源130串联连接。在开关管142为NMOSFET的情形下，开关管142的源极连接至恒流源130的高压端口，漏极连接至LED阵列110中相应列的LED灯的阴极。
比较器141的同相输入端接收用于表征恒流源130的端口电压的电压采样信号Vs，反相输入端接收参考电压Vos，输出端连接至开关管142的控制端以提供开关控制信号Vg。在该实施例中，比较器141的同相输入端与开关管142的漏极相连接，从而将开关管142的漏端电压Vd作为恒流源130的端口电压。
比较器141将恒流源130的端口电压与参考电压Vos相比较，从而产生开关控制信号Vg。当Vd＞Vos时，所述比较器141的输出结果为1，开关管142导通。当Vd＜Vos时，所述比较器141的输出结果为0，开关管142截止。
应当指出，上述限压模块140的实现仅为示例，开关管142可以是新增加的，也可以是复用恒流源端口的已有设计，其目的是可控关断。在该实施例中，限压模块140采用比较器和开关管的电路设计，这仅为限压模块的一种实现手段。在替代的实施例中，限压模块140可以为任意的电路设计，只要其在某设定电压范围内关断恒流源130即可。
上述实施例仅为举例，本发明的根本做法在于提出了一种新的LED显示装置和驱动方法，解决了现有技术存在的LED灯开短路带来的图像出错的问题，增加了显示系统可靠性，提升显示性能。
本发明的实施例如上文所述，这些实施例并没有详尽叙述所有的细节，也不限制该发明仅为所述的具体实施例。显然，根据以上描述，可作很多的修改和变化。本说 明书选取并具体描述这些实施例，是为了更好地解释本发明的原理和实际应用，从而使所属技术领域技术人员能很好地利用本发明以及在本发明基础上的修改使用。本发明的保护范围应当以本发明权利要求所界定的范围为准。

Claims (18)

  1. 一种LED显示装置，包括：
    LED阵列，包括排列成行和列的多个LED灯；
    行驱动模块，包括多个输出端，分别与所述多个LED灯中的相应行LED灯相连接，从而提供供电电压；
    多个恒流源，在所述多个LED灯中的相应行LED灯获得供电电压时，根据显示数据控制流经所述多个LED灯中的相应列LED灯的驱动电流，从而实现与显示数据相对应的亮度；以及
    多个限压模块，分别连接在所述多个LED灯中的相应列LED灯和相应恒流源之间，
    其中，所述多个限压模块在所述多个LED灯出现开短路故障时断开经由短路LED灯和开路LED灯的电流路径，以避免所述多个LED灯的异常点亮。
  2. 根据权利要求1所述的LED显示装置，其中，所述行驱动模块的多个输出端分别与所述多个LED灯的相应行LED灯的阳极相连接，所述多个恒流源，分别经由所述多个限压模块的相应限压模块连接至所述多个LED灯的相应列LED灯的阴极。
  3. 根据权利要求1所述的LED显示装置，其中，所述多个限压模块将所述多个恒流源的端口电压与参考电压相比较，根据比较结果判断所述多个LED灯是否出现开短路故障。
  4. 根据权利要求3所述的LED显示装置，其中，所述多个恒流源在未工作状态、正常工作状态、异常工作状态下的端口电压分别为第一电压、第二电压和第三电压，所述参考电压小于所述第一电压和所述第二电压，并且大于所述第三电压。
  5. 根据权利要求4所述的LED显示装置，其中，所述多个恒流源的正常工作状态中驱动电流经由第一电流路径流动，其中，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第一电流路径经由所述相应行LED灯分别到达所述多个恒流源中的相应恒流源。
  6. 根据权利要求4所述的LED显示装置，其中，所述多个恒流源的异常工作状态中驱动电流经由第二电流路径流动，其中，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第二电流路径经由短路LED灯所在行的至少一个LED灯、开路LED灯所在行的至少一个LED灯，分别到达所述多个恒流源中的相应恒流源。
  7. 根据权利要求4所述的LED显示装置，其中，所述第一电压大致等于所述供电电压，所述第二电压大致等于所述供电电压减去单个LED灯的导通压降，所述第三 电压大致等于所述供电电压减去两个LED灯串联的导通压降。
  8. 根据权利要求4所述的LED显示装置，其中，所述多个限压模块分别包括：
    比较器，所述比较器的同相输入端和反相输入端分别接收所述端口电压的电压采样信号和所述参考电压，输出端提供开关控制信号；以及
    开关管，所述开关管的控制端连接至所述比较器的输出端以接收开关控制信号，所述开关管的第一电流端和第二电流端分别连接至相应列LED灯的阴极和相应恒流源的高压端口。
  9. 根据权利要求8所述的LED显示装置，其中，所述比较器的同相输入端连接至所述开关管的第一电流端，以获得所述电压采样信号。
  10. 根据权利要求8所述的LED显示装置，还包括多个电容，所述多个电容分别连接在相应限压模块中的比较器的同相输入端和地之间，用于在帧周期中存储所述电压采样信号。
  11. 根据权利要求10所述的LED显示装置，其中，所述多个电容为寄生电容或附加电容器件。
  12. 一种用于LED显示装置的驱动方法，所述LED显示装置包括LED阵列，所述LED阵列包括排列成行和列的多个LED灯，所述方法包括：
    在每个帧周期中进行行扫描；
    在每个行周期中，分别向所述多个LED灯中的相应行LED灯提供供电电压；
    根据显示数据控制流经所述多个LED灯中的相应列LED灯的驱动电流，从而实现与显示数据相对应的亮度；以及
    在所述多个LED灯出现开短路故障时断开经由短路LED灯和开路LED灯的电流路径，以避免所述多个LED灯的异常点亮。
  13. 根据权利要求12所述的驱动方法，还包括：
    采用多个恒流源分别控制所述多个LED灯中的相应列LED灯的驱动电流；以及
    将所述多个恒流源的端口电压的电压采样信号与参考电压相比较，根据比较结果判断所述多个LED灯是否出现开短路故障。
  14. 根据权利要求13所述的驱动方法，其中，所述多个恒流源在未工作状态、正常工作状态、异常工作状态下的端口电压分别为第一电压、第二电压和第三电压，所述参考电压小于所述第一电压和所述第二电压，并且大于所述第三电压。
  15. 根据权利要求14所述的驱动方法，其中，所述多个恒流源的正常工作状态 中驱动电流经由第一电流路径流动，其中，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第一电流路径经由所述相应行LED灯分别到达所述多个恒流源中的相应恒流源。
  16. 根据权利要求14所述的驱动方法，其中，所述多个恒流源的异常工作状态中驱动电流经由第二电流路径流动，其中，在所述多个LED灯中的相应行LED灯获得供电电压时，所述第二电流路径经由短路LED灯所在行的至少一个LED灯、开路LED灯所在行的至少一个LED灯，分别到达所述多个恒流源中的相应恒流源。
  17. 根据权利要求14所述的驱动方法，其中，所述第一电压大致等于所述供电电压，所述第二电压大致等于所述供电电压减去单个LED灯的导通压降，所述第三电压大致等于所述供电电压减去两个LED灯串联的导通压降。
  18. 根据权利要求14所述的驱动方法，其中，采用电容，在帧周期中存储所述电压采样信号。
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