LED display device and driving method thereof

Abstract

The present application discloses an LED display device and a driving method thereof. The LED display device comprises: an LED array, comprising a plurality of LED lamps arranged in rows and columns; a row driving module, comprising a plurality of output terminals, respectively connected to the corresponding row LED lamps in the plurality of LED lamps, so as to provide a power supply voltage; a plurality of constant current sources, when the corresponding row LED lamps in the plurality of LED lamps obtain the power supply voltage, control the driving current flowing through the corresponding column LED lamps in the plurality of LED lamps according to the display data, so as to achieve the brightness corresponding to the display data; and a plurality of voltage limiting modules, respectively connected between the corresponding column LED lamps in the plurality of LED lamps and the corresponding constant current sources, wherein the plurality of voltage limiting modules disconnect the current path through the short-circuited LED lamp and the open-circuited LED lamp when an open-short circuit fault occurs in the plurality of LED lamps, so as to avoid abnormal lighting of the plurality of LED lamps. The LED display device can improve the image quality and reduce the power consumption when an open-short circuit fault occurs in the LED lamp.

Description

Technical Field

[0001] The present invention relates to LED display technology, and more particularly to an LED display device and a driving method thereof. Background Art

[0002] 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 shape, and are widely used in various fields such as industry, transportation, commercial advertising, information release, sports competitions, etc.

[0003] The pixel element used in the LED display device is an LED lamp, in which a plurality of LED lamps form a pixel array. During operation, for example, the LED display device scans by row, and respectively connects a constant current source in series with a selected LED, thereby lighting up the LED of the corresponding row. The current control method and the on-time control method are used to control the brightness of the selected LED, thereby realizing multi-level grayscale. In the current control method, the brightness of the LED is controlled by adjusting the current flowing through the LED. The on-time control method is to control the brightness of the LED by changing the duty cycle under the condition of constant current drive.

[0004] However, in actual use environments, LED display devices often need to work for a long time, and sometimes they are in harsh environments with high temperature and high humidity, which can easily cause damage to the LED lamps, resulting in open circuits or short circuits in the LED lamps. When an open-short circuit failure occurs in an LED lamp, not only will the damaged LED lamp itself fail to light up normally, but an unexpected current path may also be formed, causing the unselected LED lamps to light up abnormally, thereby forming abnormal pixel bright spots. This abnormal lighting phenomenon causes image abnormalities. As the area of ​​LED display devices becomes larger and larger, and the number of LED lamps increases, the probability of open-short circuits increases greatly. Once an open-short circuit problem occurs, it will greatly affect the image quality.

[0005] Therefore, it is desired to further improve the LED display device so as to improve the image quality when the LED lamp is open or short-circuited. Summary of the invention

[0006] The object of the present invention is to provide an LED display device and a driving method thereof, wherein a voltage limiting module is used to improve image quality and reduce power consumption when an open short circuit fault occurs in an LED lamp.

[0007] According to one aspect of the present invention, there is provided an LED display device, comprising: an LED array, comprising a plurality of LED lamps arranged in rows and columns; a row driving module, comprising a plurality of output terminals, respectively connected to corresponding row LED lamps among the plurality of LED lamps, so as to provide a power supply voltage; a plurality of constant current sources, which control the driving current flowing through corresponding column LED lamps among the plurality of LED lamps according to display data when corresponding row LED lamps among the plurality of LED lamps obtain the power supply voltage, so as to achieve a brightness corresponding to the display data; and a plurality of voltage limiting modules, respectively connected between corresponding column LED lamps among the plurality of LED lamps and corresponding constant current sources, wherein the plurality of voltage limiting modules disconnect the current path through the short-circuited LED lamp and the open-circuited LED lamp when an open-short circuit fault occurs to the plurality of LED lamps, so as to avoid abnormal lighting of the plurality of LED lamps.

[0008] Preferably, the plurality of constant current sources control at least one of a current value and a duty cycle of the driving current according to the display data.

[0009] Preferably, the multiple output ends of the row driving module are respectively connected to the anodes of the corresponding rows of the multiple LED lamps, and the multiple constant current sources are respectively connected to the cathodes of the corresponding columns of the multiple LED lamps via the corresponding voltage limiting modules of the multiple voltage limiting modules.

[0010] Preferably, 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 circuit faults according to the comparison results.

[0011] Preferably, the port voltages of the multiple constant current sources in a non-working state, a normal working state, and an abnormal working state are respectively a first voltage, a second voltage, and a third voltage, and the reference voltage is less than the first voltage and the second voltage, and greater than the third voltage.

[0012] Preferably, in the normal working state of the multiple constant current sources, the driving current flows via the first current path, wherein when the corresponding row of LED lights among the multiple LED lights obtains the power supply voltage, the first current path reaches the corresponding constant current source among the multiple constant current sources respectively through the corresponding row of LED lights.

[0013] Preferably, in the abnormal working state of the multiple constant current sources, the driving current flows through a second current path, wherein, when the corresponding row of LED lamps among the multiple LED lamps obtains the power supply voltage, the second current path passes through at least one LED lamp in the row where the short-circuited LED lamp is located and at least one LED lamp in the row where the open-circuited LED lamp is located, and reaches the corresponding constant current source among the multiple constant current sources respectively.

[0014] Preferably, when a corresponding row of LED lamps among the plurality of LED lamps obtains a supply voltage, the second current path is disconnected after being momentarily turned on.

[0015] Preferably, the first voltage is substantially equal to the supply voltage, the second voltage is substantially equal to the supply voltage minus a conduction voltage drop of a single LED lamp, and the third voltage is substantially equal to the supply voltage minus a conduction voltage drop of two LED lamps connected in series.

[0016] Preferably, the multiple voltage limiting modules respectively include: a comparator, whose non-inverting input terminal and inverting input terminal respectively receive the voltage sampling signal of the port voltage and the reference voltage, and whose output terminal provides a switch control signal; and a switch tube, whose control terminal is connected to the output terminal of the comparator to receive the switch control signal, and whose first current terminal and second current terminal are respectively connected to the cathode of the corresponding column of LED lights and the high-voltage port of the corresponding constant current source.

[0017] Preferably, the non-inverting input terminal of the comparator is connected to the first current terminal of the switch tube to obtain the voltage sampling signal.

[0018] Preferably, it further comprises a plurality of capacitors, which are respectively connected between the non-inverting input terminal of the comparator in the corresponding voltage limiting module and the ground, and are used to store the voltage sampling signal in a frame period.

[0019] Preferably, the plurality of capacitors are parasitic capacitors or additional capacitive devices.

[0020] According to another aspect of the present invention, there is provided a driving method for an LED display device, wherein the LED display device comprises an LED array, wherein the LED array comprises a plurality of LED lamps arranged in rows and columns, and wherein the method comprises: performing row scanning in each frame cycle; in each row cycle, respectively providing a power supply voltage to corresponding row LED lamps among the plurality of LED lamps; controlling a driving current flowing through corresponding column LED lamps among the plurality of LED lamps according to display data, thereby achieving a brightness corresponding to the display data; and disconnecting a current path passing through the short-circuited LED lamp and the open-circuited LED lamp when an open-short circuit fault occurs in the plurality of LED lamps, thereby avoiding abnormal lighting of the plurality of LED lamps.

[0021] Preferably, in the step of controlling the driving current, at least one of a current value and a duty cycle of the driving current is controlled according to the display data.

[0022] Preferably, it also includes: using multiple constant current sources to respectively control the driving current of the corresponding columns of LED lights in the multiple LED lights; and comparing the voltage sampling signals of the port voltages of the multiple constant current sources with a reference voltage, and judging whether the multiple LED lights have open-short circuit faults based on the comparison results.

[0023] Preferably, the port voltages of the multiple constant current sources in a non-working state, a normal working state, and an abnormal working state are respectively a first voltage, a second voltage, and a third voltage, and the reference voltage is less than the first voltage and the second voltage, and greater than the third voltage.

[0024] Preferably, in the normal working state of the multiple constant current sources, the driving current flows via the first current path, wherein when the corresponding row of LED lights among the multiple LED lights obtains the power supply voltage, the first current path reaches the corresponding constant current source among the multiple constant current sources respectively through the corresponding row of LED lights.

[0025] Preferably, in the abnormal working state of the multiple constant current sources, the driving current flows through a second current path, wherein, when the corresponding row of LED lamps among the multiple LED lamps obtains the power supply voltage, the second current path passes through at least one LED lamp in the row where the short-circuited LED lamp is located and at least one LED lamp in the row where the open-circuited LED lamp is located, and reaches the corresponding constant current source among the multiple constant current sources respectively.

[0026] Preferably, in a row period, when a corresponding row of LED lamps among the plurality of LED lamps obtains a supply voltage, the second current path is disconnected after being momentarily turned on.

[0027] Preferably, the first voltage is substantially equal to the supply voltage, the second voltage is substantially equal to the supply voltage minus a conduction voltage drop of a single LED lamp, and the third voltage is substantially equal to the supply voltage minus a conduction voltage drop of two LED lamps connected in series.

[0028] Preferably, a capacitor is used to store the voltage sampling signal during a frame period.

[0029] According to the LED display device and the driving method thereof of the embodiments of the present invention, a voltage limiting module is arranged between a plurality of constant current sources and the corresponding columns of LED lamps. When an open-short circuit fault occurs in the LED lamp, the voltage limiting module disconnects the current path through the short-circuited LED lamp and the open-circuited LED lamp to avoid abnormal lighting of the LED lamp, thereby improving image quality and reducing power consumption.

[0030] In a preferred embodiment, the voltage limiting module detects an open-short circuit fault according to the port voltage of the constant current source. When the port voltage is lower than a set reference voltage, the voltage limiting module disconnects the connection between the constant current source and the corresponding column of LED lamps, thereby disconnecting the current path through the short-circuited LED lamp and the open-circuited LED lamp. The voltage limiting module does not require a complex detection circuit and logic circuit, thereby further reducing the circuit cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0032] Figure 1 FIG. 4 is a schematic circuit diagram of an LED display device according to the prior art.

[0033] Figure 2 Show Figure 1 The current path when an open short circuit fault occurs in an LED lamp in an LED display device.

[0034] Figure 3 FIG. 4 is a schematic circuit diagram of an LED display device according to an embodiment of the present invention.

[0035] Figure 4 Show Figure 3 The current path when an open short circuit fault occurs in an LED lamp in an LED display device.

[0036] Figure 5 Show Figure 3 A schematic circuit diagram of a row driving module in an LED display device.

[0037] Figure 6 Show Figure 3 A schematic circuit diagram of a voltage limiting module in an LED display device. DETAILED DESCRIPTION

[0038] Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by the same or similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0039] In the present application, the term "open-short circuit" refers to a situation in which, in an LED array of an LED display device, at least one LED lamp is damaged by an open circuit and at least another LED lamp is damaged by a short circuit.

[0040] Figure 1 A schematic circuit diagram of an LED display device according to the prior art is shown. In this embodiment, the LED display device adopts a common anode solution.

[0041] As shown in the figure, the LED display device 100 includes an LED array 110, a row driver 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. In a monochrome LED display device, each pixel unit includes a monochrome LED lamp. In a color LED display device, each pixel unit includes three LED lamps, namely red, green, and blue LED lamps. The anodes of the rows of LED lamps in the LED array 110 are connected to each other. The plurality of output terminals of the row driver module 120 are respectively connected to the anodes of the corresponding rows of 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.

[0042] During operation, scanning is performed row by row in each frame period. The row driver module 120 selectively provides the power supply voltage VCC to the anode of the LED lamp of the corresponding row in the row period according to the scanning signal. When the LED lamp of the selected row is connected to the power supply voltage VCC, the constant current source 130 generates a driving current, and the current value and duty cycle of the driving current can be changed according to the display data, thereby jointly determining the brightness of the LED lamp. At any time, only one scanning signal is valid, which determines that at any time, only the LED lamp of the row corresponding to the scanning signal receives the power supply voltage VCC and lights up, and the LED lamps of the remaining rows are extinguished.

[0043] In the frame period, the multiple LED lights in the pixel array are scanned in rows, and the constant current source provides a constant current to the selected LED lights according to the display data. Therefore, the brightness values ​​of the multiple LED lights in the pixel array correspond to the grayscale values ​​of the multiple pixel units in the frame picture, thereby realizing the display of the frame picture.

[0044] Figure 2 Show Figure 1 The current path when an open-short circuit fault occurs in an LED lamp in an LED display device. The equivalent circuit diagram when the LED lamp in the xth row and yth column is short-circuited is shown in the figure.

[0045] exist Figure 2 In the LED display device 100 shown, multiple LED lamps in the pixel array are scanned row by row. When the row driving module 120 supplies power to multiple LED lamps in the (x+m)th row, the LED lamps in the (x+m)th row and the (y+n)th column receive the power supply voltage VCC.

[0046] When the LED lamp in the (x+m)th row (y+n)th column is not open, the first current path is formed. That is, the LED lamp is turned on, forming a current path through the LED lamp in the (x+m)th row (y+n)th column. The LED lamps in the (x+m)th row are all normally lit, and the LED lamps in the remaining rows are all normally extinguished.

[0047] In the case where the LED lamp in the (x+m)th row (y+n)th column is open-circuited, a second current path is formed. That is, the LED lamp is disconnected, and a current path is formed through the LED lamp in the xth row (y)th column and the LED lamp in the xth row (y+n)th column. The LED lamps in the (x+m)th row except the yth column and the (y+n)th column are all normally lit, however, the LED lamp in the (x+m)th row (y)th column and the LED lamp in the xth row (y+n)th column are abnormally lit.

[0048] Specifically, when the LED lamp in the (x+m)th row and (y+n)th column is open-circuited, the first current path is blocked. If the LED lamp in the same column as the LED lamp in the xth row and yth column on the selected row does not need to be lit, that is, Figure 2 The LED lamp in the (x+m)th row and yth column does not need to be lit. Since the power supply voltage VCC of the LED lamp in the (x+m)th row is 5V and the LED lamp in the xth row and yth column is short-circuited, there will be a path from the LED lamp in the (x+m)th row and yth column, the LED lamp in the xth row and yth column, and the LED lamp in the xth row and (y+n) column to the constant current source and to the ground, that is, Figure 2 The second current path shown will cause the LED lamp in the (x+m)th row and yth column and the LED lamp in the xth row and (y+n)th column to light up abnormally.

[0049] Figure 3 FIG. 4 is a schematic circuit diagram of an LED display device according to an embodiment of the present invention.

[0050] As shown in the figure, the LED display device 200 includes an LED array 110, a row driver 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. In a monochrome LED display device, each pixel unit includes a monochrome LED lamp. In a color LED display device, each pixel unit includes three LED lamps, which are red, green, and blue LED lamps. The anodes of the rows of LED lamps in the LED array 110 are connected to each other. The plurality of output terminals of the row driver module 120 are respectively connected to the anodes of the corresponding rows of 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 voltage limiting module 140 and the constant current source 130.

[0051] In this embodiment, the supply voltage VCC is, for example, 5V, and the on-state voltage drop Von of each LED lamp is approximately 2-3V.

[0052] Multiple constant current sources 130 are connected to the cathodes of multiple LED lamps in corresponding columns via corresponding voltage limiting modules 140, so as to provide constant current when the LED lamps are turned on. For example, the magnitude of the constant current provided by the constant current source 130 and the duty cycle of the on time jointly determine the brightness of the LED lamp.

[0053] During operation, scanning is performed row by row in each frame period. The row driver module 120 selectively provides the power supply voltage VCC to the anode of the LED lamp of the corresponding row in the row period according to one of the scan signals SCAN1 to SCANn. When the LED lamp of the selected row is connected to the power supply voltage VCC, the constant current source 130 generates a driving current, and the current value and duty cycle of the driving current can be changed according to the display data, thereby jointly determining the brightness of the LED lamp. At any time, only one scan signal is valid, which determines that at any time, only the LED lamp of the row corresponding to the scan signal receives the power supply voltage VCC and lights up, and the LED lamps of the remaining rows are extinguished.

[0054] In the frame period, the multiple LED lights in the pixel array are scanned in rows, and the constant current source provides a constant current to the selected LED lights according to the display data. Therefore, the brightness values ​​of the multiple LED lights in the pixel array correspond to the grayscale values ​​of the multiple pixel units in the frame picture, thereby realizing the display of the frame picture.

[0055] and Figure 1 Unlike the LED display device 100 of the prior art shown in the figure, the LED display device 200 according to this embodiment includes a voltage limiting module 140. The voltage limiting module 140 detects the 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 turn off, thereby disconnecting the current path of the LED lamps in the corresponding column. Even when the LED lamps in the LED display device have an open short circuit fault, the LED display device 200 can avoid abnormal lighting of multiple LED lamps, thereby improving image quality.

[0056] Figure 4 Show Figure 3 The current path when an open short circuit fault occurs in an LED lamp in an LED display device.

[0057] As described above, in the LED display device 200 of this embodiment, 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 not working, and a second voltage V2 when working normally, and the first voltage V1 is higher than the second voltage V2. For example, the first voltage V1=power supply voltage VCC, and the second voltage V2=power supply voltage VCC-on-state voltage drop Von of the LED lamp.

[0058] When an open-circuit or short-circuit LED lamp in the LED array occurs, a current path is formed through the row where the short-circuit LED lamp is located and the column where the open-circuit LED lamp is located. At the constant current source 130 in the column where the open-circuit LED lamp is located, the port voltage of the constant current source 130 is a third voltage V3, and the third voltage V3 is an abnormal voltage. The third voltage V3 = the power supply voltage VCC - the on-state voltage drop Von of the LED lamp*2.

[0059] In this embodiment, 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 circuit. For example, assuming that the power supply voltage VCC = 5V, the on-state voltage drop Von of the LED lamp = 2V, when the LED lamp is normally lit, the port voltage of the constant current source 130 is the second voltage V2 = 3V, and when the LED lamp is open and short circuited, the port voltage of the constant current source 130 is the third voltage V3 = 1V. At this time, the reference voltage Vos can be set to be slightly lower than 3V.

[0060] For example, in Figure 3 In the LED display device shown, it is assumed that the row where the short-circuited LED lamp is located is the xth row, and the column where the open-circuited LED lamp is located is the (y+n)th column. For example, the LED lamp in the xth row and yth column is short-circuited, and the LED lamp n rows and m columns away from the LED lamp, that is, the LED lamp in the (x+m)th row and (y+n)th column is open-circuited. When the (x+m)th row line is enabled, the LED lamp in this row receives the power supply voltage VCC.

[0061] If the LED lamp in the (x+m)th row and (y+n)th column is not open-circuited, the LED lamp is turned on. At this time, the voltage limiting module 140 detects that the port voltage of the constant current source 130 in the corresponding column is the second voltage V2 = the power supply voltage VCC - the on-state voltage drop Von of the LED lamp = 3V. The second voltage V2 is higher than the reference voltage Vos, and the constant current source 130 works normally and outputs a pull-down constant current, thereby forming a first current path through the LED lamp.

[0062] If the LED lamp in the (x+m)th row and (y+n)th column is open-circuited, the LED lamp is turned off. At this time, the voltage limiting module 140 detects that the port voltage of the constant current source 130 in the corresponding column is the third voltage V3 = the power supply voltage VCC - the conduction voltage drop Von*2 of the LED lamp = 1V. 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 of the current path through the row where the short-circuited LED lamp is located and the column where the open-circuited LED lamp is located.

[0063] The following describes the working process of the voltage limiting module 140 in conjunction with the frame period of the LED display device 200. Figure 3In the LED display device 200 shown in FIG. 1 , it is assumed that the row where the short-circuited LED lamp is located is the xth row, and the column where the open-circuited LED lamp is located is the (y+n)th column. For example, the LED lamp in the xth row and yth column is short-circuited, and the LED lamp n rows and m columns away from the LED lamp, that is, the LED lamp in the (x+m)th row and (y+n)th column is open-circuited. The equivalent circuit is as follows: Figure 4 shown.

[0064] In this embodiment, capacitor C represents the parasitic capacitance widely present in the LED display device. In an alternative embodiment, capacitor C is an additional capacitor device connected between the input terminal of the voltage limiting module and the ground. As described below, capacitor C is used to store the port voltage of the constant current source 130 during the frame period.

[0065] In each frame period, the row driving module 120 will control the power supply end to sequentially provide the power supply voltage VCC to each row of LED lamps in the LED array 120 , that is, each row of LED lamps will light up sequentially.

[0066] Before the row where the open LED lamp is located is lit, when the LED lamp in the column where the open LED lamp is located is lit, the port voltage of the constant current source 130 of the column is the second voltage V2=3V. When the lighting time of the LED lamp in the column ends and the corresponding constant current source is turned off, due to the existence of parasitic capacitance, the port voltage of the constant current source 130 of the column will continue to be maintained at 3V. Afterwards, if the LED lamp in the column does not need to be lit, the port voltage of the constant current source 130 of the column will always be maintained at 3V.

[0067] When the row of the open-circuit (x+m)th row (y+n) column where the LED lamp is located is lit, that is, the (x+m)th row line is enabled and receives the power supply voltage VCC, if the LED lamp of the (x+m)th row (y+n) column needs to be lit, there is an instantaneous path from the LED lamp of the (x+m)th row y column, the LED lamp of the xth row y column, and the LED lamp of the xth row (y+n) column to the constant current source to the ground, which will cause the port voltage of the constant current source of the (y+n)th column to drop to 1V instantaneously. At this time, the voltage limiting module 140 starts working. Since the port voltage of the constant current source 130 is lower than the set reference voltage Vos, the constant current source 130 of the column will be immediately turned off, thereby disconnecting the second current path. After disconnection, the port voltage of the constant current source 130 of the column will remain at 1V until the next time the LED lamp of the column is normally lit, the voltage is restored to 3V.

[0068] In a frame period, before the open-circuit LED lamp in the (x+m)th row and (y+n)th column is lit, when no LED lamps in the same column as the open-circuit LED lamp are lit and only the open-circuit LED lamp has been lit, according to the previous analysis, the port voltage of the constant current source 130 of the column is 1V at this time;

[0069] When the row of LED lights in the open (x+m)th row and (y+n)th column is lit, that is, the (x+m)th row line is enabled and receives the power supply voltage VCC, the voltage limiting module 140 detects that the constant current source port voltage = 1V, which is lower than the set reference voltage, and will not turn on the constant current source, so the second current path cannot be formed until the next time an LED light in the column is normally lit, and the voltage returns to 3V.

[0070] Therefore, even when an open-short circuit fault occurs in an LED lamp in the LED display device, the LED display device 200 can prevent abnormal lighting of multiple LED lamps, thereby improving image quality.

[0071] Figure 5 Show Figure 3 A schematic circuit diagram of a row driving module in an LED display device.

[0072] In the LED display device 200, the row driving module 120 includes a plurality of switch tubes 121, such as P-type metal oxide semiconductor field effect transistors (PMOSFET), with a source as a first end connected to a power supply voltage VCC and a drain as a second end connected to the anode of the LED in the corresponding row in the LED array 110.

[0073] During operation, the driving module 120 selectively turns on the plurality of switch tubes 121 according to one of the scan signals SCAN1 to SCANn, and provides the supply voltage VCC to the anodes of the LED lamps in the corresponding row via the selected switch tubes 121 .

[0074] Figure 6 Show Figure 3 A schematic circuit diagram of a voltage limiting module in an LED display device.

[0075] In the LED display device 200, the voltage limiting module 140 can be implemented in a variety of ways. Figure 6 As shown, the voltage limiting module 140 includes a comparator 141 and a switch tube 142. The switch tube 142 is, for example, an N-type metal oxide semiconductor field effect transistor (NMOSFET).

[0076] The switch tube 142 in the voltage limiting module 140 is connected in series with the constant current source 130. When the switch tube 142 is an NMOSFET, the source of the switch 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 LED lamp of the corresponding column in the LED array 110.

[0077] The non-inverting input terminal of the comparator 141 receives the 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 switch tube 142 to provide the switch control signal Vg. In this embodiment, the non-inverting input terminal of the comparator 141 is connected to the drain of the switch tube 142, so that the drain voltage Vd of the switch tube 142 is used as the port voltage of the constant current source 130.

[0078] The comparator 141 compares the terminal voltage of the constant current source 130 with the reference voltage Vos, thereby generating a switch control signal Vg. When Vd>Vos, the output result of the comparator 141 is 1, and the switch tube 142 is turned on. When Vd<Vos, the output result of the comparator 141 is 0, and the switch tube 142 is turned off.

[0079] It should be noted that the implementation of the above-mentioned voltage limiting module 140 is only an example, and the switch tube 142 can be a newly added one, or it can be an existing design of a multiplexed constant current source port, and its purpose is to controllably shut down. In this embodiment, the voltage limiting module 140 adopts a circuit design of a comparator and a switch tube, which is only a means of implementing the voltage limiting module. In an alternative embodiment, the voltage limiting module 140 can be any circuit design, as long as it shuts off the constant current source 130 within a certain set voltage range.

[0080] The above embodiments are only examples. The fundamental approach of the present invention is to propose a new LED display device and driving method, which solves the problem of image errors caused by open and short circuits of LED lamps in the prior art, increases the reliability of the display system, and improves the display performance.

[0081] The embodiments of the present invention are as described above, and these embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and the modified use based on the present invention. The scope of protection of the present invention shall be based on the scope defined by the claims of the present invention.

Claims

1. An LED display device, comprising: LED arrays, including a plurality of LED lights arranged in rows and columns; A row driving module, comprising a plurality of output terminals, respectively connected to corresponding rows of LED lamps in the plurality of LED lamps, so as to provide a supply voltage; a plurality of constant current sources, which control the driving current flowing through the corresponding columns of the plurality of LED lamps according to the display data when the corresponding rows of the plurality of LED lamps obtain the power supply voltage, so as to achieve the brightness corresponding to the display data; as well as A plurality of voltage limiting modules are respectively connected between corresponding columns of LED lamps in the plurality of LED lamps and corresponding constant current sources, The multiple constant current sources are connected to the cathodes of the corresponding columns of the multiple LED lamps via the corresponding voltage limiting modules of the multiple voltage limiting modules respectively, and the multiple voltage limiting modules compare the port voltages of the multiple constant current sources with the reference voltage, and determine whether the multiple LED lamps have an open-short circuit fault according to the comparison result, and disconnect the current path through the short-circuited LED lamp and the open-circuited LED lamp when the open-short circuit fault occurs in the multiple LED lamps, so as to avoid abnormal lighting of the multiple LED lamps. In an abnormal working state of the multiple constant current sources, the driving current flows via a second current path. When the LED lamps in a corresponding row among the multiple LED lamps obtain a power supply voltage, the second current path passes through at least one LED lamp in the row where the short-circuited LED lamp is located and at least one LED lamp in the row where the open-circuited LED lamp is located, and reaches the corresponding constant current source among the multiple constant current sources respectively. The short-circuited LED lamp and the open-circuited LED lamp are located in different rows.

2. The LED display device according to claim 1, wherein: The multiple output terminals of the row driving module are respectively connected to the anodes of the LED lamps in corresponding rows of the multiple LED lamps.

3. The LED display device according to claim 1, wherein: The port voltages of the multiple constant current sources in the non-working state, the normal working state, and the abnormal working state are respectively the first voltage, the second voltage, and the third voltage. The reference voltage is less than the first voltage and the second voltage, and greater than the third voltage.

4. The LED display device according to claim 3, wherein: In normal working state of the multiple constant current sources, the driving current flows via the first current path, wherein when the corresponding row of LED lights among the multiple LED lights obtains the power supply voltage, the first current path reaches the corresponding constant current source among the multiple constant current sources via the corresponding row of LED lights.

5. The LED display device according to claim 3, wherein: The first voltage is substantially equal to the supply voltage, the second voltage is substantially equal to the supply voltage minus the conduction voltage drop of a single LED lamp, and the third voltage is substantially equal to the supply voltage minus the conduction voltage drop of two LED lamps connected in series.

6. The LED display device according to claim 3, wherein: The plurality of voltage limiting modules respectively include: A comparator, wherein the non-inverting input terminal and the inverting input terminal of the comparator receive the voltage sampling signal of the port voltage and the reference voltage respectively, and the output terminal provides a switch control signal; and A switch tube, wherein the control end of the switch tube is connected to the output end of the comparator to receive a switch control signal, and the first current end and the second current end of the switch tube are respectively connected to the cathode of the corresponding column LED lamp and the high voltage port of the corresponding constant current source.

7. The LED display device according to claim 6, wherein: The non-inverting input terminal of the comparator is connected to the first current terminal of the switch tube to obtain the voltage sampling signal.

8. The LED display device according to claim 6, further comprising a plurality of capacitors, wherein 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 used to store the voltage sampling signal in a frame period.

9. The LED display device according to claim 8, wherein: The plurality of capacitors are parasitic capacitors or additional capacitor devices.

10. A driving method for an LED display device, the LED display device comprising an LED array, the LED array comprising a plurality of LED lamps arranged in rows and columns, the method comprising: Performing line scanning in each frame period; In each row cycle, supplying a supply voltage to the LED lamps in corresponding rows among the plurality of LED lamps; A plurality of constant current sources are used to control the driving current flowing through the corresponding columns of the plurality of LED lamps according to the display data, so as to achieve the brightness corresponding to the display data. The multiple constant current sources are respectively connected to the cathodes of the corresponding columns of the multiple LED lamps via corresponding voltage limiting modules, the voltage limiting modules compare the port voltage of the corresponding constant current source with the reference voltage, determine whether the multiple LED lamps have an open-short circuit fault according to the comparison result, and disconnect the current path through the short-circuited LED lamp and the open-circuited LED lamp when the open-short circuit fault occurs in the multiple LED lamps, so as to avoid abnormal lighting of the multiple LED lamps. In an abnormal working state of the multiple constant current sources, the driving current flows via a second current path, wherein, when the corresponding row of LED lamps among the multiple LED lamps obtains a power supply voltage, the second current path passes through at least one LED lamp in the row where the short-circuited LED lamp is located and at least one LED lamp in the row where the open-circuited LED lamp is located, and reaches the corresponding constant current source among the multiple constant current sources respectively, and the short-circuited LED lamp and the open-circuited LED lamp are located in different rows.

11. The driving method according to claim 10, wherein: The port voltages of the multiple constant current sources in the non-working state, the normal working state, and the abnormal working state are respectively the first voltage, the second voltage, and the third voltage. The reference voltage is less than the first voltage and the second voltage, and greater than the third voltage.

12. The driving method according to claim 11, wherein: In normal working state of the multiple constant current sources, the driving current flows via the first current path, wherein when the corresponding row of LED lights among the multiple LED lights obtains the power supply voltage, the first current path reaches the corresponding constant current source among the multiple constant current sources via the corresponding row of LED lights.

13. The driving method according to claim 11, wherein: The first voltage is substantially equal to the supply voltage, the second voltage is substantially equal to the supply voltage minus the conduction voltage drop of a single LED lamp, and the third voltage is substantially equal to the supply voltage minus the conduction voltage drop of two LED lamps connected in series.

14. The driving method according to claim 11, wherein: The sampling capacitor stores a voltage sampling signal of the port voltage in a frame period.

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