Display including abnormality detection circuit of light emitting diode string

Abstract

The invention discloses an abnormity detection circuit of a light emitting diode string, in which a current generation circuit provides current to the light emitting diode string through an output point OUT, and is used for detecting open circuit and short circuit abnormity of the light emitting diode string under the condition that a comparator is used.

Description

[0001] This application is a divisional application of the invention patent application with application number 2024113609613. The filing date of the original application is September 27, 2024. Technical Field

[0002] The present application belongs to the field of abnormal circuit detection, and relates to the design of a test circuit for open circuit and short circuit abnormalities of a light emitting diode string. Background Art

[0003] Light-emitting diodes play an important role in modern displays, especially liquid crystal displays (LCDs), which use a series of multiple light-emitting diodes. In addition to displays, there are also some applications that use light-emitting diode strings.

[0004] When using LED strings, a circuit is required to provide current and the associated open and short circuit detection errors. Figure 1 , which is a circuit diagram of a conventional light emitting diode channel 100. The light emitting diode channel 100 includes at least one light emitting diode string 110 and a channel circuit 150. The light emitting diode string 110 includes a plurality of light emitting diodes connected in series, such as Figure 1 The LEDs 111, 112 and 113 are shown. The channel circuit 150 connects the output OUT to the LED string 110 through a contact point or pin.

[0005] The channel circuit 150 includes three circuit modules, namely, an open circuit detection circuit 120, a short circuit detection circuit 130, and a current generating circuit 140. The open circuit detection circuit 120 is used to detect whether the LEDs in the LED string 110 are open circuited. The short circuit detection circuit 130 is used to detect whether the LEDs in the LED string 110 are short circuited. The current generating circuit 140 is used to generate a current for controlling the brightness of the LED string 110.

[0006] Please refer to Figure 2 , which is a circuit diagram of a conventional open circuit detection circuit 120. The open circuit detection circuit 120 includes a voltage comparator 210, a first input of which is connected to the output OUT of the channel circuit 150, and a second input of which is connected to an open circuit reference voltage VREF_OLED. When the light emitting diodes in the light emitting diode string 110 are open circuited, the current generating circuit 140 will pull down the voltage of the output OUT. When the voltage value of the output OUT is lower than the open circuit reference voltage VREF_OLED, the voltage comparator 210 will output a high potential, and it is determined that the light emitting diodes in the light emitting diode string 110 are open circuited.

[0007] Please refer to Figure 3, which is a circuit diagram of a conventional short circuit detection circuit 130. The short circuit detection circuit 130 includes a first resistor 310, a second resistor 320, and a voltage comparator 330. A first end of the first resistor 310 is connected to an output OUT. A second end of the second resistor 320 is connected to a ground potential. A second end of the first resistor 310, a first end of the second resistor 320, and a first input end of the voltage comparator 330 are connected to each other. A second input end of the voltage comparator 330 is connected to a short circuit reference voltage VREF_SLED.

[0008] When the LEDs in the LED string 110 are short-circuited, the LED string 110 will pull up the voltage of the output OUT. After the voltage of the output OUT is divided by the voltage divider circuit formed by the first resistor 310 and the second resistor, it will be higher than the short-circuit reference voltage VREF_SLED. Accordingly, the voltage comparator 330 will output a high potential, judging that the LEDs in the LED string 110 are short-circuited.

[0009] from Figure 2 and Figure 3 It can be seen that the channel circuit 150 includes two voltage comparators, namely the voltage comparator 210 of the open circuit detection circuit 120 and the voltage comparator 330 of the short circuit detection circuit 130. Since the comparator circuit occupies a large chip area, its power consumption is large. When applied to modern displays, there are hundreds or thousands of LED channels 100, and each LED channel 100 has two comparator circuits, which occupies a large chip area and consumes power.

[0010] Therefore, there is an urgent need for a circuit design that can reduce the chip area and power consumption of the channel circuit 150, reduce costs, and reduce size, so as to increase competitiveness. Summary of the invention

[0011] The present application is to provide an abnormality detection circuit for a light emitting diode string in order to solve the deficiencies in the prior art, with the aim of reducing costs, reducing size, reducing power consumption, and increasing product competitiveness.

[0012] In order to achieve the above purpose, this application adopts the following technical solutions:

[0013] According to an embodiment of the present application, an abnormality detection circuit for a light-emitting diode string is provided, wherein a current generating circuit provides a current to the light-emitting diode string through an output point OUT, and is characterized in that it includes: a first resistor, whose first end is connected to the output point OUT; a second resistor, whose first end is connected to the second end of the first resistor; a first transistor, used to connect the second end of the second resistor to the ground potential, and whose gate is connected to a control signal; a reference voltage multiplexer, used to receive the control signal so as to select an output from a short-circuit reference voltage and an open-circuit reference voltage; a comparator, whose first input end is connected to the second end of the first resistor and the first end of the second resistor, and whose second input end receives the output of the reference voltage multiplexer; a first inverter, used to receive the output of the comparator; and an output inversion multiplexer, used to receive the control signal so as to select one from the output of the comparator and the output of the first inverter as the output of the abnormality detection circuit.

[0014] Preferably, in order to perform a short-circuit test, it is characterized in that when the control signal is a high voltage, the first transistor is turned on, the reference voltage multiplexer selects the short-circuit reference voltage to be output to the second input terminal of the comparator, the first input terminal of the comparator is the resistance divider of the output point OUT, and the output reverse multiplexer selects the output of the comparator as the output of the abnormality detection circuit.

[0015] Preferably, in order to perform an open circuit test, it is characterized in that when the control signal is at a low voltage, the first transistor is turned off, the reference voltage multiplexer selects the open circuit reference voltage to be output to the second input terminal of the comparator, the first input terminal of the comparator corresponds to the voltage of the output point OUT, and the output reverse multiplexer selects the output of the first inverter as the output of the abnormality detection circuit.

[0016] Preferably, in order to perform a short-circuit test, it is characterized in that the short-circuit reference voltage is between 2V and 12V.

[0017] Preferably, in order to perform an open circuit test, the open circuit reference voltage is between 0.2V and 0.4V.

[0018] Preferably, in order to switch between different test modes, the first transistor is an N-type transistor.

[0019] Preferably, in order to report the detected abnormality, it is characterized in that when the output of the abnormality detection circuit is at a high potential, it indicates that the abnormality detection circuit detects that the light emitting diode string has an abnormality.

[0020] Preferably, in order to automatically switch between different test modes, it is characterized in that it also includes: a second transistor, whose gate is connected to the output point OUT; a second inverter, whose input is connected to the output of a current source and the source of the second transistor, and whose output serves as the control signal; and the current source.

[0021] Preferably, in order to adapt to different applications, it is characterized in that the source of the second transistor is connected to one of the following: a ground potential; and the aforementioned open-circuit reference voltage.

[0022] According to an embodiment of the present application, a light emitting diode channel is provided, characterized by comprising: a light emitting diode string as described above; a current providing circuit; and an abnormality detecting circuit.

[0023] According to an embodiment of the present application, a display is provided, characterized by comprising a plurality of light emitting diode channels as described above.

[0024] According to one embodiment of the present application, a method for detecting an abnormality of a light-emitting diode string is provided, wherein a current generating circuit provides a current to the light-emitting diode string through an output point OUT, and is characterized in that it includes: receiving a detection mode control signal; when the detection mode control signal indicates a signal of a short-circuit test mode, performing the following steps: obtaining a resistance divided voltage of the output point OUT; obtaining a short-circuit reference voltage; and comparing the resistance divided voltage of the output point OUT with the short-circuit reference voltage as a comparison result; when the detection mode control signal indicates a signal of an open-circuit test mode, performing the following steps: obtaining a voltage corresponding to the output point OUT; obtaining a short-circuit reference voltage; comparing the voltage corresponding to the output point OUT with the short-circuit reference voltage as a comparison result; and inverting the comparison result; and outputting the comparison result.

[0025] Preferably, in order to adapt to different applications, it is characterized in that before the above-mentioned step of receiving the detection mode control signal, the following steps are further performed: comparing the output point OUT voltage with a reference voltage to obtain a voltage difference; and when the voltage difference is greater than a critical voltage, setting the detection mode control signal to the short circuit detection mode signal; when the voltage difference is less than the critical voltage, setting the detection mode control signal to the open circuit detection mode signal.

[0026] Preferably, in order to adapt to different applications, the reference voltage is one of the following: ground potential; and the aforementioned open-circuit reference voltage.

[0027] Due to the adoption of the above solution, the beneficial effects of the present application are: reducing costs, reducing size, reducing power consumption, and increasing product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. 1 is a circuit diagram of a conventional light emitting diode channel 100 .

[0029] Figure 2 is a circuit diagram of a conventional open circuit detection circuit 120 .

[0030] Figure 3 is a circuit diagram of a conventional short circuit detection circuit 130 .

[0031] Figure 4 FIG. 4 is a circuit diagram of a light emitting diode channel 400 according to an embodiment of the present application.

[0032] Figure 5 FIG. 4 is a circuit diagram of an abnormality detection circuit 420 according to an embodiment of the present application.

[0033] Figure 6 FIG. 4 is a schematic diagram of a circuit for detecting short circuits by the abnormality detection circuit 420 .

[0034] Figure 7 FIG. 4 is a schematic diagram of a circuit for detecting an open circuit by the abnormality detection circuit 420 .

[0035] Figure 8 FIG. 8 is a circuit diagram of a light emitting diode channel 800 according to another embodiment of the present application.

[0036] Fig. 9 FIG. 8 is a circuit diagram of a pre-detection circuit 830 and an abnormality detection circuit 820 according to an embodiment of the present application.

[0037] Fig.10 FIG. 8 is a circuit diagram of a pre-detection circuit 830 and an abnormality detection circuit 820 according to another embodiment of the present application.

[0038] Fig.11 FIG. 1 is a flow chart of a method 1100 for detecting abnormality of a light emitting diode string according to an embodiment of the present application.

[0039] Fig.12 FIG. 1 is a flow chart of a method 1200 for detecting abnormality of a light emitting diode string according to an embodiment of the present application. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other implementation methods obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] The terms "first", "second", "third", etc. (if any) in the specification and claims of this application and the drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the objects described in these descriptions can be interchanged where appropriate. In the description of this application, "plurality" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or in one or more hardware circuits or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0042] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0043] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In order to make the purpose, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with drawings and specific implementation methods.

[0045] One of the inventive features of the present application is to combine the open circuit detection circuit 120 and the short circuit detection circuit 130 of the channel circuit 150 to form an integrated abnormality detection circuit for detecting open circuit and short circuit. In the above-mentioned integrated abnormality detection circuit, the number of comparators can be reduced from two to one, so as to reduce cost and power consumption, reduce size, and increase competitiveness.

[0046] Please refer to Figure 4, which is a circuit diagram of an LED channel 400 according to an embodiment of the present application. The LED channel 400 is different from the conventional LED channel 100 in that the channel circuit 450 included in the LED channel 400 does not have independent open circuit detection circuits 120 and short circuit detection circuits 130, but has an integrated abnormality detection circuit 420 for detecting open circuits and short circuits of the LED string 110.

[0047] Please refer to Figure 5 , which is a circuit diagram of an abnormality detection circuit 420 according to an embodiment of the present application. The abnormality detection circuit 420 also includes a first resistor 510 and a second resistor 520. The first end of the first resistor 510 is connected to the output OUT. The first end of the second resistor 520, the second end of the first resistor 510 and the first input end of the comparator 550 are connected to each other. The second end of the second resistor 520 is connected to the drain of the N-type transistor 530. The source of the N-type transistor 530 is connected to the ground potential. The gate of the N-type transistor 530 is connected to a control signal DET_CTRL.

[0048] The abnormality detection circuit 520 includes two multiplexers or selectors, namely, a reference voltage multiplexer 540 and an output inverse multiplexer 570. The two input terminals of the reference voltage multiplexer 540 are respectively connected to the short-circuit reference voltage VREF_SLED and the open-circuit reference voltage VREF_OLED. The reference voltage multiplexer 540 receives the control of the control signal DET_CTRL. When the control signal DET_CTRL is set to a high level (logic 1), the reference voltage multiplexer 540 outputs the short-circuit reference voltage VREF_SLED to the second input terminal of the comparator 550. On the contrary, when the control signal DET_CTRL is set to a low level (logic 0), the reference voltage multiplexer 540 outputs the open-circuit reference voltage VREF_OLED to the second input terminal of the comparator 550.

[0049] The first input terminal of the output inverse multiplexer 570 is connected to the output of the comparator 550, and the second input terminal of the output inverse multiplexer 570 is connected to the inverse output of the comparator 550, that is, the inverse output of the output of the comparator 550 after passing through an inverter 560. When the control signal DET_CTRL is set to a high level (logic 1), the output inverse multiplexer 570 outputs the output of the comparator 550. On the contrary, when the control signal DET_CTRL is set to a low level (logic 0), the output inverse multiplexer 570 outputs the inverse output of the comparator 550.

[0050] and Figure 2 and Figure 3Compared with the short-circuit detection circuit 130, the open-circuit detection circuit 120 shown in the figure has a reduced comparator circuit in the abnormality detection circuit 420, and two multiplexers 540 and 570, a transistor 530 and an inverter 560 are added. These added components will not generate additional power consumption, and the required area is smaller than the comparator circuit. Therefore, compared with the traditional channel circuit 150, the channel circuit 450 provided in the present application has a smaller area and power consumption.

[0051] Please refer to Figure 6 , which is a circuit diagram of the abnormality detection circuit 420 for short circuit detection. In the short circuit detection mode, the control signal DET_CTRL is set to a high potential (logic 1). When the light-emitting diodes in the light-emitting diode string 110 are short-circuited, the light-emitting diode string 110 will pull up the voltage of the output OUT. The transistor 530 is turned on by the control signal DET_CTRL. The voltage of the output OUT is transmitted to the first input terminal (positive terminal) of the comparator 550 after the resistance voltage is divided by the first resistor 510 and the second resistor 520. The reference voltage multiplexer 540 outputs the short circuit reference voltage VREF_SLED to the second input terminal (negative terminal) of the comparator 550.

[0052] The comparator 550 compares whether the resistor-divided voltage of the OUT voltage at the first input terminal is greater than the short-circuit reference voltage VREF_SLED at the second input terminal. When the voltage at the first input terminal is greater than the short-circuit reference voltage VREF_SLED at the second input terminal, the comparator 550 outputs a high potential (logic 1) to the first input terminal of the output reverse multiplexer 570. When the voltage at the first input terminal is less than the short-circuit reference voltage VREF_SLED at the second input terminal, the comparator 550 outputs a low potential (logic 0) to the first input terminal of the output reverse multiplexer 570. At this time, the output reverse multiplexer 570 is set by the high potential control signal DET_CTRL, and the comparison result of the comparator 550 is output. In other words, when the output reverse multiplexer 570 outputs a high potential, it indicates that the LED string 110 is short-circuited. Otherwise, the LED string 110 is not short-circuited.

[0053] Please refer to Figure 7, which is a circuit diagram of the abnormality detection circuit 420 for open circuit detection. In the open circuit detection mode, the control signal DET_CTRL is set to a low potential (logic 0). When the light-emitting diodes in the light-emitting diode string 110 are open, the current generating circuit 140 will pull down the voltage of the output OUT. The transistor 530 is turned off by the control signal DET_CTRL, so the second resistor 520 will not flow current. The voltage of the output OUT enters the first input terminal (positive terminal) of the comparator 550 through the first resistor 510. The reference voltage multiplexer 540 outputs the open circuit reference voltage VREF_OLED to the second input terminal (negative terminal) of the comparator 550.

[0054] The comparator 550 compares whether the voltage of the first input terminal corresponding to the OUT voltage is greater than the open circuit reference voltage VREF_OLED of the second input terminal. When the voltage of the first input terminal is greater than the open circuit reference voltage VREF_OLED of the second input terminal, the comparator 550 outputs a high potential (logic 1) to the inverter 560. When the voltage of the first input terminal is less than the open circuit reference voltage VREF_OLED of the second input terminal, the comparator 550 outputs a low potential (logic 0) to the inverter 560. At this time, the output reverse multiplexer 570 is set by the low potential control signal DET_CTRL, and outputs the output of the inverter 560, that is, the reverse output of the comparison result of the comparator 550. In other words, when the output reverse multiplexer 570 outputs a high potential, it indicates that the LED string 110 is open-circuited. Otherwise, the LED string 110 is not open-circuited.

[0055] exist Figures 5 to 7 In the embodiment shown, the control signal DET_CTRL inputted from the outside of the abnormality detection circuit 420 is responsible for switching the open circuit and short circuit detection modes. Generally speaking, the aforementioned open circuit reference voltage VREF_OLED is usually between 0.2V and 0.4V, and the short circuit reference voltage VREF_SLED is usually between 2V and 12V. If it is possible to roughly detect whether the OUT voltage compared with the above two reference voltages is high or low, it is possible to switch to the corresponding detection mode.

[0056] For example, a simple pre-detection circuit can be used to determine the level of the OUT voltage. When the OUT voltage is high, it means that short circuit detection is required, and the control signal DET_CTRL can be set to a high level. Conversely, when the OUT voltage is high, it means that open circuit detection is required, and the control signal DET_CTRL can be set to a low level. Therefore, the open circuit or short circuit detection mode can be automatically switched in the channel circuit.

[0057] Please refer to Figure 8FIG. 8 is a circuit diagram of a light emitting diode channel 800 according to another embodiment of the present application. Figure 4 The difference of the channel circuit 450 shown is that the channel circuit 850 includes a pre-detection circuit 830 for controlling the open circuit or short circuit detection mode of the abnormality detection circuit 420 .

[0058] Please refer to Fig. 9 FIG. 8 is a schematic diagram of a circuit of a pre-detection circuit 830 and an abnormality detection circuit 820 according to an embodiment of the present application. Figure 5 The difference of the channel circuit 450 is that the gate of the N-type transistor 530, the reference voltage multiplexer 540 and the output demultiplexer 570 are controlled by the output signal of the pre-detection circuit 830 instead of the external input control signal DET_CTRL.

[0059] The pre-detection circuit 830 comprises a current source 910, an N-type transistor 920 and an inverter 930. The current source 910 is connected to the drain of the N-type transistor 920 and the inverter 930, the source of the N-type transistor 920 is connected to the ground potential, and the gate of the N-type transistor 920 is connected to the output OUT.

[0060] When the output OUT voltage is greater than the threshold voltage of the N-type transistor 920, which is usually 0.5V to 0.7V, the N-type transistor 920 is turned on and the VA voltage is pulled down. After the reverse action of the inverter 930, the control signal DET_CTRL is set to a high level, and the abnormality detection circuit 820 is set to detect a short circuit mode.

[0061] On the contrary, when the output OUT voltage is less than the threshold voltage of the N-type transistor 920, which is usually 0.5V to 0.7V, the N-type transistor 920 is turned off. At this time, the current source 910 pulls up the VA voltage. After the reverse action of the inverter 930, the control signal DET_CTRL is set to a low potential, and the abnormality detection circuit 820 is set to detect an open circuit mode.

[0062] exist Fig. 9 In the embodiment of , since the source of the N-type transistor 920 is connected to the ground potential, it is used to detect the potential difference or absolute voltage between the output OUT voltage and the ground potential. Fig.10 , which is a circuit diagram of a pre-detection circuit 830 and an abnormality detection circuit 820 according to another embodiment of the present application. Fig. 9 The embodiment shown differs in that Fig.10The source of the N-type transistor 920 shown is not connected to the ground potential, but to the open-circuit reference voltage VREF_OLED. In this way, the N-type transistor 920 is used to detect the relative voltage between the output OUT voltage and the open-circuit reference voltage VREF_OLED. When the output OUT voltage is close to the open-circuit reference voltage VREF_OLED, it means that an open-circuit protection detection is to be performed, otherwise a short-circuit protection detection is to be performed. When the output OUT voltage is higher than the open-circuit reference voltage VREF_OLED by a critical voltage, the control signal DET_CTRL will be set to a high potential, and short-circuit protection detection is performed at this time; when the output OUT voltage minus the open-circuit reference voltage VREF_OLED is lower than a critical voltage, the control signal DET_CTRL will be set to a low potential, and open-circuit protection detection is performed at this time. Fig. 9 and Fig.10 The embodiments are two different design concepts, which can be used optimally in different applications.

[0063] exist Fig. 9 and Fig.10 In the embodiment, when the outside world wants to know the current detection mode, the control signal DET_CTRL can be connected. When the control signal DET_CTRL is at a high level (logic 1), it indicates that a short circuit test is being performed. On the contrary, when the control signal DET_CTRL is at a low level (logic 0), it indicates that an open circuit test is being performed.

[0064] Please refer to Fig.11 FIG. 1 is a flow chart of a method 1100 for detecting abnormality of a light emitting diode string according to an embodiment of the present application. The abnormality detection method 1100 may be Figure 4 The channel circuit 420 shown is implemented. If there is no direct or indirect causal relationship between any two steps, the present application does not limit the execution order of the two steps. The abnormality detection method 1100 can start from step 1110.

[0065] Step 1110: Receive a detection mode control signal.

[0066] Step 1120: Determine whether the detection mode control signal indicates open circuit detection or short circuit detection. When the detection mode control signal indicates short circuit detection, the process proceeds to step 1130. Otherwise, when the detection mode control signal indicates open circuit detection, the process proceeds to step 1160.

[0067] Step 1130: Obtain the resistor-divided voltage of the OUT voltage output to the LED string.

[0068] Step 1140: Obtain a short-circuit reference voltage.

[0069] Step 1150: Compare the resistor-divided voltage of the OUT voltage with the short-circuit reference voltage. When the former is higher, the comparison result is a high potential (logic 1). Otherwise, the comparison result is a low potential (logic 0).

[0070] Step 1160: Obtain a voltage corresponding to the OUT voltage. The voltage corresponding to the OUT voltage drops after passing through the first resistor.

[0071] Step 1170: Obtain an open-circuit reference voltage.

[0072] Step 1180: Compare the voltage corresponding to the OUT voltage with the open circuit reference voltage. When the former is higher, the comparison result is a high potential (logic 1). Otherwise, the comparison result is a low potential (logic 0).

[0073] Step 1190: Invert the comparison result obtained in step 1180, that is, invert the high potential to a low potential, or invert the low potential to a high potential.

[0074] Step 1199: Output the comparison result of step 1150 or step 1190.

[0075] Regardless of whether the detection mode control signal indicates an open circuit test or a short circuit test, as long as the comparison result outputted in step 1199 is a high voltage (logic 1), it indicates that there is an abnormality in the LED string.

[0076] Please refer to Fig.12 FIG. 1 is a flow chart of a method 1200 for detecting abnormality of a light emitting diode string according to an embodiment of the present application. The abnormality detection method 1200 may be Fig. 9 or Fig.10 If there is no direct or indirect causal relationship between any two steps, the present application does not limit the execution order of the two steps. The abnormality detection method 1200 can start from step 1210.

[0077] Step 1210: Compare the OUT voltage output to the LED string with a reference voltage to obtain a voltage difference. Fig. 9 For the channel circuit shown, the reference voltage can be ground potential. Fig.10 When the channel circuit is shown, the reference voltage may be an open-circuit reference voltage VREF_OLED.

[0078] Step 1220: Determine whether the voltage difference is greater than a critical voltage. The critical voltage may be, for example, a critical voltage of transistor 920. When the voltage difference is greater than the critical voltage, the process proceeds to step 1230. On the contrary, when the voltage difference is less than the critical voltage, the process proceeds to step 1240.

[0079] Step 1230: Set the detection mode control signal to a short circuit detection mode signal, which may be a high voltage (logic 1).

[0080] Step 1240: Set the detection mode control signal to the open circuit detection mode signal, which may be a low voltage (logic 0).

[0081] Regardless of whether the process proceeds to step 1230 or step 1240, the detection mode control signal can be used to perform Fig.11 Anomaly detection method 1100 is described.

[0082] The transistor described in the present application may be a field effect transistor made of a metal oxide semiconductor. A person skilled in the art may understand that an N-type transistor may be replaced by a P-type transistor using an equivalent circuit, and vice versa. The above-mentioned transistor may also be replaced by other forms of switching circuits.

[0083] According to an embodiment of the present application, an abnormality detection circuit for a light-emitting diode string is provided, wherein a current generating circuit provides a current to the light-emitting diode string through an output point OUT, and is characterized in that it includes: a first resistor, whose first end is connected to the output point OUT; a second resistor, whose first end is connected to the second end of the first resistor; a first transistor, used to connect the second end of the second resistor to the ground potential, and whose gate is connected to a control signal; a reference voltage multiplexer, used to receive the control signal so as to select an output from a short-circuit reference voltage and an open-circuit reference voltage; a comparator, whose first input end is connected to the second end of the first resistor and the first end of the second resistor, and whose second input end receives the output of the reference voltage multiplexer; a first inverter, used to receive the output of the comparator; and an output inversion multiplexer, used to receive the control signal so as to select one from the output of the comparator and the output of the first inverter as the output of the abnormality detection circuit.

[0084] Preferably, in order to perform a short-circuit test, it is characterized in that when the control signal is a high voltage, the first transistor is turned on, the reference voltage multiplexer selects the short-circuit reference voltage to be output to the second input terminal of the comparator, the first input terminal of the comparator is the resistance divider of the output point OUT, and the output reverse multiplexer selects the output of the comparator as the output of the abnormality detection circuit.

[0085] Preferably, in order to perform an open circuit test, it is characterized in that when the control signal is at a low voltage, the first transistor is turned off, the reference voltage multiplexer selects the open circuit reference voltage to be output to the second input terminal of the comparator, the first input terminal of the comparator corresponds to the voltage of the output point OUT, and the output reverse multiplexer selects the output of the first inverter as the output of the abnormality detection circuit.

[0086] Preferably, in order to perform a short-circuit test, it is characterized in that the short-circuit reference voltage is between 2V and 12V.

[0087] Preferably, in order to perform an open circuit test, the open circuit reference voltage is between 0.2V and 0.4V.

[0088] Preferably, in order to switch between different test modes, the first transistor is an N-type transistor.

[0089] Preferably, in order to report the detected abnormality, it is characterized in that when the output of the abnormality detection circuit is at a high potential, it indicates that the abnormality detection circuit detects that the light emitting diode string has an abnormality.

[0090] Preferably, in order to automatically switch between different test modes, it is characterized in that it also includes: a second transistor, whose gate is connected to the output point OUT; a second inverter, whose input is connected to the output of a current source and the source of the second transistor, and whose output serves as the control signal; and the current source.

[0091] Preferably, in order to adapt to different applications, it is characterized in that the source of the second transistor is connected to one of the following: a ground potential; and the aforementioned open-circuit reference voltage.

[0092] According to an embodiment of the present application, a light emitting diode channel is provided, characterized by comprising: a light emitting diode string as described above; a current providing circuit; and an abnormality detecting circuit.

[0093] According to an embodiment of the present application, a display is provided, characterized by comprising a plurality of light emitting diode channels as described above.

[0094] According to one embodiment of the present application, a method for detecting an abnormality of a light-emitting diode string is provided, wherein a current generating circuit provides a current to the light-emitting diode string through an output point OUT, and is characterized in that it includes: receiving a detection mode control signal; when the detection mode control signal indicates a signal of a short-circuit test mode, performing the following steps: obtaining a resistance divided voltage of the output point OUT; obtaining a short-circuit reference voltage; and comparing the resistance divided voltage of the output point OUT with the short-circuit reference voltage as a comparison result; when the detection mode control signal indicates a signal of an open-circuit test mode, performing the following steps: obtaining a voltage corresponding to the output point OUT; obtaining a short-circuit reference voltage; comparing the voltage corresponding to the output point OUT with the short-circuit reference voltage as a comparison result; and inverting the comparison result; and outputting the comparison result.

[0095] Preferably, in order to adapt to different applications, it is characterized in that before the above-mentioned step of receiving the detection mode control signal, the following steps are further performed: comparing the output point OUT voltage with a reference voltage to obtain a voltage difference; and when the voltage difference is greater than a critical voltage, setting the detection mode control signal to the short circuit detection mode signal; when the voltage difference is less than the critical voltage, setting the detection mode control signal to the open circuit detection mode signal.

[0096] Preferably, in order to adapt to different applications, it is characterized in that the reference voltage is one of the following: ground potential; and the aforementioned open circuit reference voltage.

[0097] The present application provides an abnormality detection circuit design that can reduce the chip area and power consumption of a channel circuit, thereby reducing costs, reducing size, reducing power consumption, and increasing product competitiveness.

[0098] The above is only a preferred specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes within the technical scope disclosed in the present application according to the technical solution and application concept of the present application, which should be covered by the protection scope of the present application.

Claims

1. A display, characterized in that: The method comprises a plurality of light emitting diode channels, wherein any one of the plurality of light emitting diode channels comprises: LED string; a current generating circuit, which provides current to the LED string through an output point OUT; and The abnormality detection circuit comprises: A first resistor, a first end of which is connected to the output point OUT; a second resistor having a first end connected to the second end of the first resistor; A first transistor, used for connecting the second end of the second resistor to the ground potential, and having a gate connected to a control signal; A reference voltage multiplexer, for receiving the control signal so as to select an output from a short-circuit reference voltage and an open-circuit reference voltage; a comparator having a first input terminal connected to the second terminal of the first resistor and the first terminal of the second resistor, and a second input terminal receiving the output of the reference voltage multiplexer; A first inverter, used for receiving the output of the comparator; as well as The output inversion multiplexer is used for receiving the control signal so as to select one of the output of the comparator and the output of the first inverter as the output of the abnormality detection circuit.

2. The display according to claim 1, characterized in that When the control signal is at a high voltage, the first transistor is turned on, the reference voltage multiplexer selects the short-circuit reference voltage to be output to the second input terminal of the comparator, the first input terminal of the comparator is the resistance divider of the output point OUT, and the output reverse multiplexer selects the output of the comparator as the output of the abnormality detection circuit.

3. The display according to claim 1, wherein: When the control signal is at a low level, the first transistor is turned off, the reference voltage multiplexer selects the open-circuit reference voltage to be output to the second input terminal of the comparator, the first input terminal of the comparator corresponds to the voltage of the output point OUT, and the output reverse multiplexer selects the output of the first inverter as the output of the abnormality detection circuit.

4. The display according to claim 1, wherein: The short-circuit reference voltage is between 2V and 12V, the open-circuit reference voltage is between 0.2V and 0.4V, and the first transistor is an N-type transistor.

5. The display according to claim 1, wherein: When the output of the abnormality detection circuit is at a high level, it indicates that the abnormality detection circuit detects that the light emitting diode string is abnormal.

6. The display according to claim 1, wherein: The abnormality detection circuit also includes: A second transistor, a gate of which is connected to the output point OUT; A second inverter, whose input is connected to the output of a current source and the source of the second transistor, and whose output serves as the control signal; and The current source.

7. The display according to claim 6, characterized in that The source of the second transistor is connected to one of the following: ground potential; and The aforementioned open circuit reference voltage.

Images