CN107863073B - LCOALDIMMING backlight driving circuit and display device - Google Patents
LCOALDIMMING backlight driving circuit and display device Download PDFInfo
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- CN107863073B CN107863073B CN201711427471.0A CN201711427471A CN107863073B CN 107863073 B CN107863073 B CN 107863073B CN 201711427471 A CN201711427471 A CN 201711427471A CN 107863073 B CN107863073 B CN 107863073B
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- 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
- G09G3/34—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 by control of light from an independent source
- G09G3/3406—Control of illumination source
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Abstract
The invention discloses an LCOALDIMMING backlight driving circuit and a display device, wherein the circuit comprises a power bus, a signal acquisition module, a signal processing module, a main control module and a power protection module, wherein the input end of the signal acquisition module is connected with the power bus, and the output end of the signal acquisition module is connected with the input end of the signal processing module; the controlled end of the signal processing module is connected with the control end of the main control module, and the output end of the signal processing module is connected with the input end of the power protection module; the signal acquisition module acquires a square wave signal of the power bus, converts the square wave signal into a comparative level signal and then couples and outputs the comparative level signal; the signal processing module is controlled by the main control module and triggers the signal power supply protection module to work so as to control the power supply bus to stop power supply output when the received trigger signal is greater than a preset voltage threshold value. The invention solves the problem of surface temperature of devices such as LED lamps and the like caused by short circuit of a switching device.
Description
Technical Field
The invention relates to the technical field of backlight display, in particular to a liquid crystal on insulator (LCOALDIMMING) backlight driving circuit and a display device.
Background
At present, local dim im in a liquid crystal television with high resolution and large size is mostly provided with a local dim im in-phase driving circuit to drive a plurality of groups of backlight LED lamps to work, however, as the number of backlight LED lamp strings increases, the current on the power supply bus is inevitably larger. Once a short circuit phenomenon occurs in a switching device in a driving circuit, the surface temperature of devices such as an LED lamp and the like is easily increased to exceed a safety limit, and even if the devices are seriously heated, surrounding structural members are ignited due to high temperature, and a malignant fault phenomenon that a television is burnt occurs.
Disclosure of Invention
The invention mainly aims to provide an LCOALDIMMING backlight driving circuit and a display device, and aims to solve the problem that the surface temperature of devices such as an LED lamp and the like is rapidly increased to exceed a safety limit value due to the short circuit of a switching device, and even the surrounding structural parts are ignited due to high temperature in serious conditions to cause the malignant fault of burning a television.
In order to achieve the above object, the present invention provides an lcoal luminance backlight driving circuit, which includes a power bus, a signal acquisition module, a signal processing module, a main control module and a power protection module, wherein an input end of the signal acquisition module is connected to the power bus, and an output end of the signal acquisition module is connected to an input end of the signal processing module; the controlled end of the signal processing module is connected with the control end of the main control module, and the output end of the signal processing module is connected with the input end of the power protection module; wherein the content of the first and second substances,
the signal acquisition module is used for acquiring the square wave signal of the power bus, converting the square wave signal into a comparative level signal and then coupling and outputting the comparative level signal;
and the signal processing module outputs a corresponding trigger signal based on the control of the main control module and according to the received comparison level signal.
And the power supply protection module is used for controlling the power supply bus to stop power supply output when the received trigger signal is greater than a preset voltage threshold value.
Preferably, the lcoal luminance backlight driving circuit further includes a temperature sensing module for collecting the temperature of the power bus switch, the temperature sensing module is disposed close to the power bus switch, and an output end of the temperature sensing module is connected to an input end of the signal processing module.
Preferably, the lcoal luminance backlight driving circuit further includes a signal amplifying module, and the signal amplifying module is serially connected between the signal collecting module and the signal processing module, and/or serially connected between the temperature sensing module and the signal processing module.
Preferably, the temperature sensing module includes a thermistor and a voltage dividing resistor, a first end of the voltage dividing resistor is connected to the first dc power supply, a second end of the voltage dividing resistor is connected to the first end of the thermistor, and a second end of the thermistor is grounded.
Preferably, the signal acquisition module includes a plurality of signal acquisition branches, the number of the plurality of signal acquisition branches corresponds to the number corresponding to the power bus, and the input ends of the plurality of signal acquisition branches are connected with the power bus in a one-to-one correspondence manner; and the output ends of the signal acquisition branches are connected with the input ends of the signal processing module in a one-to-one correspondence manner.
Preferably, the signal acquisition branch comprises a coupling unit, a rectifying unit and a low-pass filtering unit, an input end of the coupling unit is an input end of the signal acquisition branch, and an output end of the coupling unit is connected with an output end of the rectifying unit; the output end of the rectification unit is the output end of the signal acquisition unit and is connected with the input end of the low-pass filtering unit.
Preferably, the coupling unit includes a first capacitor, a first end of the first capacitor is an input end of the coupling unit, and a second end of the first capacitor is an output end of the coupling unit.
Preferably, the signal processing module includes an operational amplifier and a control chip, an input end of the operational amplifier is an input end of the signal processing module, and an output end of the operational amplifier is connected with an input end of the control chip; the output end of the control chip is the output end of the signal processing module.
Preferably, the signal processing module includes a first resistor, a second resistor, a third resistor, a first electronic switch and a second capacitor, a controlled terminal of the first electronic switch is an input terminal of the signal processing module and is connected to a first terminal of the first resistor, an input terminal of the first electronic switch is interconnected to a second dc power supply and a second terminal of the first resistor via the second resistor, and an output terminal of the first electronic switch is an output terminal of the signal processing module and is interconnected to a first terminal of the third resistor and a first terminal of the second capacitor; and the second end of the third resistor and the second end of the second capacitor are both grounded.
The invention also provides a display device, comprising the lcoaldiming backlight driving circuit; the LCOALDIMMING backlight driving circuit comprises a power bus, a signal acquisition module, a signal processing module, a main control module and a power protection module, wherein the input end of the signal acquisition module is connected with the power bus of the LCOALDIMMING backlight driving circuit, and the output end of the signal acquisition module is connected with the input end of the signal processing module; the controlled end of the signal processing module is connected with the control end of the main control module, and the output end of the signal processing module is connected with the input end of the power protection module; the signal acquisition module is used for acquiring a square wave signal of the power bus, converting the square wave signal into a comparative level signal and then coupling and outputting the comparative level signal; the signal processing module is used for outputting a corresponding trigger signal based on the control of the main control module and according to the received comparison level signal; and the power supply protection module is used for controlling the power supply bus to stop power supply output when the received trigger signal is greater than a preset voltage threshold value.
The invention collects the square wave signal on the power output bus by arranging the signal collection module, converts the square wave signal into the comparison level and outputs the comparison level to the signal processing module. The signal processing module works under the control of the main control module, and when the received level signal output by the signal acquisition module is smaller than or equal to a preset comparison level signal, the square wave signal output by the power supply bus PB is abnormal, namely a high level or low level signal is always output, the signal processing module outputs a high level trigger signal PT to the power supply protection module, and triggers the power supply protection module to work, namely the protection function of the power supply is triggered, so that the driving power supply of the display device stops outputting the power supply to the power supply bus PB of the LED lamp string. Therefore, the working state of the power bus PB can be directly fed back according to the comparison level output by the signal acquisition module. The invention solves the problem that the surface temperature of devices such as LED lamps and the like is rapidly increased to exceed the safety limit value due to the short circuit of a switching device in a driving circuit, and even the surrounding structural parts are ignited due to high temperature in serious conditions, thereby causing the serious fault of burning the television.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a functional block diagram of an embodiment of an LCOALDIMMING backlight driving circuit applied to a display device according to the present invention;
FIG. 2 is a circuit diagram of a first embodiment of the LCOALDIMMING backlight driving circuit according to the present invention;
fig. 3 is a circuit structure diagram of a second embodiment of the LCOALDIMMING backlight driving circuit of the present invention.
The reference numbers illustrate:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| 10 | Signal acquisition module | NT | |
| 20 | Signal processing module | C1 | |
| 30 | Main control module | C2 | |
| 40 | Power supply protection module | C3 | |
| 50 | Temperature sensing module | D1 | First diode |
| 11 | Signal acquisition branch | D2 | Second diode |
| 111 | Coupling unit | R0 | |
| 112 | Rectifying unit | R1 | A |
| 113 | Low-pass filtering unit | R2 | Second resistance |
| VCC1 | First direct current power supply | R3 | Third resistance |
| VCC2 | Second DC power supply | R4 | Fourth resistance |
| Q1 | First electronic switch |
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The invention provides an LCOALDIMMING backlight driving circuit which is applied to a display device.
The display device can be a display device with a display panel, such as a mobile phone, a tablet computer, a notebook computer, a palm computer, a liquid crystal television and the like. The Liquid Crystal television may be a Liquid Crystal Display device such as a TFT-LCDTFT-LCD (Thin Film Transistor Liquid Crystal Display).
In the liquid crystal display television, a local dimming driving circuit is mostly arranged to drive the backlight LED lamp to work, and the local dimming driving circuit plays a very important role in improving the density of the backlight light source, reducing the driving cost and the like, so that the local dimming circuit driven in a time-sharing mode can be applied to a high-resolution large-size television needing to further increase the number of backlight partitions.
The LOCALDIMMIN backlight driving circuit is provided with a plurality of driving switch devices for driving the corresponding LED lamp strings to work. However, as the number of backlight LED strings in a high resolution large size television increases, the current on the power bus of the driving power supply in the local dim im in the backlight driving circuit is necessarily large. Once a short circuit phenomenon occurs in a switching device in a driving circuit, the surface temperature of devices such as an LED lamp and the like is rapidly increased to exceed a safety limit value due to large driving current, and even a malignant fault phenomenon that a television is burnt due to the fact that surrounding structural members are ignited due to high temperature in serious cases occurs.
In order to solve the above problem, referring to fig. 1, in an embodiment of the present invention, the lcoal luminance driving circuit includes a signal acquisition module 10, a signal processing module 20, a main control module 30, and a power protection module 40, an input end of the signal acquisition module 10 is connected to the power bus PB, and an output end of the signal acquisition module 10 is connected to an input end of the signal processing module 20; the controlled end of the signal processing module 20 is connected with the control end of the main control module 30, and the output end of the signal processing module 20 is connected with the input end of the power protection module 40; wherein the content of the first and second substances,
the signal acquisition module 10 is configured to acquire a square wave signal of the power bus PB, convert the square wave signal into a comparative level signal, and then couple and output the comparative level signal;
the signal processing module 20 outputs a corresponding trigger signal according to the received comparison level signal under the control of the main control module 30.
The power protection module 40 is configured to control the power bus PB to stop power output when the received trigger signal is greater than a preset voltage threshold.
It should be noted that the power bus PB, which is a power supply bus for the anode of the LED light string in the LOCAL DIMMING time-sharing backlight driving circuit, includes a plurality of power switches; under the control of a signal output by a television host, a plurality of switches are sequentially and independently closed, and a direct-current power supply is connected to the anode of the corresponding LED dot matrix module to realize the lighting of the LED; the closing time of each switch is the same, and the switch is disconnected after the lighting time is over. The master control output signal is a square wave pulse signal, so that each switch is modulated by a periodic square wave signal with the same frequency and pulse width, wherein the phase of each switch is different, and the switches are basically driven in parallel and in a staggered way in the same switching period. The waveform of power bus PB driven at the switch is also a square wave signal of fixed frequency and pulse width.
In this embodiment, the signal acquisition module 10 is a small signal processing unit, which is used to effectively acquire the square wave signal on the power output bus and convert the square wave signal into a comparison level signal. When the power bus PB normally works, the signal acquisition module 10 can always acquire a comparative level through a square wave signal; when the power bus PB works abnormally, for example, when the power switch is short-circuited, the square wave signal output by the power bus PB is abnormal and will always maintain a high level or a low level, and at this time, the signal acquisition module 10 cannot acquire the square wave signal and outputs a small voltage smaller than the comparison level. Therefore, according to the magnitude of the comparison level signal output by the signal acquisition module 10, the working state of the power bus PB can be directly fed back.
The main control module 30 may be a main controller of the backlight driving circuit or a core SOC of the liquid crystal television. Mainly giving an enable signal of the signal processing module: before the system does not work normally, the enabling pin is low, and the signal processing module 20 does not work; after the system is normally started, the enable pin is at a high level, and the signal processing module 20 starts to operate normally.
The signal processing module 20, which is equivalent to a signal amplifying and converting module, based on the control of the main control module 30, for example, when the lcd tv is powered on for operation, that is, after the system of the display device is turned on, an enable signal may be output to control the signal processing module 20 to operate, for example, by cutting off the power supply of the signal processing module 20, and generally, the power supply voltage of the signal processing module 20 is 3.3V. When the comparison level signal output by the received signal acquisition module 10 is greater than the preset comparison level threshold, it indicates that the square wave signal output by the power bus PB is normal, the signal processing module 20 does not trigger the power protection module 40 to work, at this time, the trigger signal output by the signal processing module 20 is less than 3V, which is a low level, and the power protection module 40 does not work or is in a standby state. When the comparison level signal output by the signal acquisition module 10 is smaller than or equal to the preset comparison level threshold, it indicates that the square wave signal output by the power bus PB is abnormal, i.e. a high level or low level signal is always output, the signal processing module 20 outputs a high level trigger signal PT to the power protection module 40, and at this time, the voltage value of the trigger signal is larger than 3V, i.e. high level, so as to trigger the power protection module 40 to work, and trigger the protection function of the power supply, so that the power supply module of the display device stops outputting the power supply to the power bus PB of the LED light string.
The invention collects the square wave signal on the power output bus by arranging the signal collecting module 10, converts the square wave signal into a comparison level and outputs the comparison level to the signal processing module 20. The signal processing module 20 works under the control of the main control module 30, and when the received level signal output by the signal acquisition module 10 is smaller than or equal to the preset comparison level signal, the square wave signal output by the power supply bus PB is abnormal at this time, that is, a high level or low level signal is always output, the signal processing module 20 outputs a high level trigger signal PT to the power supply protection module 40, and triggers the power supply protection module 40 to work, that is, triggers the protection function of the power supply, so that the driving power supply of the display device stops outputting the power supply bus PB, and the power supply bus PB is controlled to stop outputting power to the LED lamp strings. Therefore, according to the comparison level output by the signal acquisition module 10, the working state of the power bus PB can be directly fed back. The invention solves the problem that the surface temperature of devices such as LED lamps and the like is rapidly increased to exceed the safety limit value due to the short circuit of a switching device in a driving circuit, and even the surrounding structural parts are ignited due to high temperature in serious conditions, thereby causing the serious fault of burning the television.
Referring to fig. 1 to 3, in a preferred embodiment, the lcoal luminance backlight driving circuit further includes a temperature sensing module 50 for acquiring a temperature of the switch of the power bus PB, the temperature sensing module 50 is disposed close to the switch of the power bus PB, and an output end of the temperature sensing module 50 is connected to an input end of the signal processing module 20.
It can be understood that, when a short circuit occurs in a switching device, the surface temperature of devices such as LED lamps will rapidly rise, the present invention further provides a temperature sensing module 50 to sense the temperature of each power switch of the power bus PB, when the temperature of the power switch of the power bus PB is sensed to be greater than a preset temperature threshold, for example, when one or more power switches in the power bus PB are abnormal, a level signal corresponding to the temperature output by the temperature sensing module 50 is greater than a preset comparison level threshold, and the comparison level signal is output to the signal processing module 20, so that the signal processing module 20 outputs a high level trigger signal PT to the power protection module 40 to trigger the power protection module 40 to operate. In this embodiment, the preset temperature threshold may be set according to the number of the power switches, and when the number of the light strings is large and the number of the power switches is large, the preset temperature threshold may be set relatively higher, otherwise, the preset temperature threshold may be set relatively lower.
In the above embodiment, the temperature sensing module 50 includes a thermistor NT and a voltage dividing resistor R0, a first end of the voltage dividing resistor R0 is connected to a first dc power source VCC1, a second end of the voltage dividing resistor R0 is connected to the first end of the thermistor NT, and a second end of the thermistor NT is grounded.
In this embodiment, the thermistor NT may be implemented by using a negative temperature coefficient thermistor NT, or implemented by sampling a positive temperature coefficient thermistor NT. The resistance value of the negative temperature coefficient thermistor NT decreases with the increase of the detected temperature, and the resistance value of the positive temperature coefficient thermistor NT increases with the increase of the detected temperature. The ntc thermistor NT is installed in close proximity to the switches of the power supply buses PB, and senses the temperature of each switch of the power supply buses PB after the display device operates. When the switch temperature of the power bus PB is high to a certain degree, the resistance value of the ntc thermistor NT is reduced accordingly. At this time, the negative temperature coefficient thermistor NT and the voltage dividing resistor R0 form a voltage dividing circuit, and according to the voltage dividing principle, the smaller the ratio between the negative temperature coefficient thermistor NT and the voltage dividing resistor R0, the smaller the voltage divided by the voltage dividing resistor R0, that is, the smaller the comparison level signal output to the signal sampling module, and when the comparison level signal is less than or equal to the preset comparison level threshold, the signal processing module 20 triggers the power protection module 40 to operate. Of course, in other embodiments, the logic of the actual setting circuit may be set to increase proportionally with the temperature change, and is not limited herein.
Referring to fig. 1 to 3, in a preferred embodiment, the lcoal luminance driving circuit further includes a signal amplifying module (not shown), which is serially disposed between the signal collecting module 10 and the signal processing module 20, and/or serially disposed between the temperature sensing module 50 and the signal processing module 20.
In this embodiment, the signal discharging module is arranged to amplify the level comparison signal corresponding to the temperature output by the temperature sensing module 50 and the comparison level signal corresponding to the square wave signal output by the signal acquisition module 10, and then output the amplified level comparison signal to the signal processing module 20, so as to improve the sensitivity of the signal processing module 20 to the comparison level signal.
Referring to fig. 1 to 3, in a preferred embodiment, the signal acquisition module 10 includes a plurality of signal acquisition branches 11, the number of the signal acquisition branches 11 corresponds to the number of the power bus PB, and the input ends of the signal acquisition branches 11 are connected to the power bus PB in a one-to-one correspondence manner; the output ends of the signal acquisition branches 11 are connected with the input ends of the signal processing module 20 in a one-to-one correspondence manner.
It should be noted that, in display devices such as liquid crystal televisions and computers, the backlight-driven power bus PB may be set to multiple paths, generally, at least two paths, in this embodiment, a plurality of signal acquisition branches 11 are provided corresponding to the number of the power buses PB, and the plurality of signal acquisition branches 11 respectively acquire the square wave signals output by each power bus PB, convert the acquired square wave signals into comparative level signals, and output the comparative level signals to the signal processing module 20.
Referring to fig. 1 to fig. 3, in a preferred embodiment, the signal acquisition branch 11 includes a coupling unit 111, a rectifying unit 112 and a low-pass filtering unit 113, an input end of the coupling unit 111 is an input end of the signal acquisition branch 11, and an output end of the coupling unit 111 is connected to an output end of the rectifying unit 112; the output end of the rectifying unit 112 is the output end of the signal collecting unit, and is connected with the input end of the low-pass filtering unit 113.
In this embodiment, the coupling unit 111 is configured to couple the alternating-current square-wave signal to filter a direct-current signal in the square-wave signal, and then output the direct-current signal to the rectifying unit 112 for rectification, and then the detected square-wave envelope is filtered by the low-pass filtering unit 113 to filter a high-frequency noise in the square-wave envelope, so as to obtain a comparison level signal.
The coupling unit 111 includes a first capacitor C1, a first terminal of the first capacitor C1 is an input terminal of the coupling unit 111, and a second terminal of the first capacitor C1 is an output terminal of the coupling unit 111. According to the characteristics of the capacitors of alternating current and direct current passing, the first capacitor C1 filters out the direct current component in the square wave signal. The rectifying unit 112 includes a first diode D1 and a second diode D2, and the first diode D1 and the second diode D2 constitute a full-phase rectifying circuit and form a complete current loop with the first capacitor C1. The low pass filter unit 113 includes a third capacitor C3 and a fourth resistor R4, and in this embodiment, the voltage value of the optimal comparison level signal can be adjusted by adjusting the resistance of the fourth resistor R4.
Referring to fig. 1 to 3, in a preferred embodiment, the signal processing module 20 may be implemented by an integrated circuit such as an operational amplifier and a control chip, or may be implemented by a simple amplifying circuit composed of discrete components such as a resistor, a capacitor, and a switching tube. When the sampling operational amplifier, the control chip and other integrated circuits are implemented, the Schmidt input characteristic of a comparison level signal can be realized, namely, the protection is triggered at a high temperature value, and the protection function is quitted at a low temperature value. When the amplifying circuit with simple sampling is realized, the circuit structure is simple and easy to realize, and the cost of the LCOALDIMMING backlight driving circuit is lower, so that the production cost of the display device is reduced.
When the signal processing module 20 is implemented by an integrated circuit such as an operational amplifier and a control chip, the input terminal of the operational amplifier is the input terminal of the signal processing module 20, and the output terminal of the operational amplifier is connected to the input terminal of the control chip; the output end of the control chip is the output end of the signal processing module 20.
In this embodiment, the operational amplifier is used to compare and analyze the received level signal, and when the level signal is greater than the preset comparison level threshold, the inverted level signal is output to the control chip, so that the control signal outputs a high-level trigger signal to the power protection module 40.
When a simple amplifying circuit is used for implementation, the signal processing module 20 includes a first resistor R1, a second resistor R2, a third resistor R3, a first electronic switch Q1 and a second capacitor C2, a controlled terminal of the first electronic switch Q1 is an input terminal of the signal processing module 20 and is connected to a first terminal of the first resistor R1, an input terminal of the first electronic switch Q1 is interconnected to a second dc power supply VCC2 and a second terminal of the first resistor R1 through the second resistor R2, and an output terminal of the first electronic switch Q1 is an output terminal of the signal processing module 20 and is interconnected to a first terminal of the third resistor R3 and a first terminal of the second capacitor C2; the second terminal of the third resistor R3 and the second terminal of the second capacitor C2 are both grounded.
In this embodiment, the first electronic switch Q1 may be implemented by a sampling transistor, a MOS transistor, an IGBT, and other switching transistors, and this embodiment is preferably implemented by a PNP type transistor. Setting parameters of peripheral passive devices of the PNP type triode, such as a first resistor R1, a second resistor R2, a third resistor R3, a second capacitor C2 and the like, to set a static working point of the PNP type triode, namely, a preset comparison level threshold; when the level signal input by the temperature sensing module 50 or the signal sampling module is lower than the preset comparison level threshold, the PNP type triode is in saturation conduction, and therefore the collector and the emitter of the PNP type triode are equivalent to short circuit, and at the moment, the second resistor R2 and the third resistor R3 are connected in series for voltage division, so that the voltage of the second direct current power supply VCC2 is divided and then a high-level trigger signal is output to the power supply protection module 40, and therefore the trigger protection module works to cut off the power supply output to the power supply bus PB.
It is understood that the first dc power source VCC1 and the second dc power source VCC2 may be implemented by using the same power source, for example, a power source with a voltage value of 3.3V, so as to save circuit cost.
The invention also provides a display device comprising the lcoaldiming backlight driving circuit. The detailed structure of the lcoal lcd backlight driving circuit can refer to the above embodiments, and is not described herein; it can be understood that, since the lcoaldiming backlight driving circuit is used in the display device of the present invention, the embodiment of the display device of the present invention includes all technical solutions of all embodiments of the lcoaldiming backlight driving circuit, and the achieved technical effects are also completely the same, and are not described herein again.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (7)
1. The LCOALDIMMING backlight driving circuit is characterized by comprising a power bus, a signal acquisition module, a signal processing module, a main control module and a power protection module, wherein the input end of the signal acquisition module is connected with the power bus, and the output end of the signal acquisition module is connected with the input end of the signal processing module; the controlled end of the signal processing module is connected with the control end of the main control module, and the output end of the signal processing module is connected with the input end of the power protection module; wherein, the first and the second end of the pipe are connected with each other,
the signal acquisition module is used for acquiring the square wave signal of the power bus, converting the square wave signal into a comparative level signal and then coupling and outputting the comparative level signal;
the signal processing module is used for outputting a corresponding trigger signal based on the control of the main control module and according to the received comparison level signal;
the power supply protection module is used for controlling the power supply bus to stop power supply output when the received trigger signal is greater than a preset voltage threshold;
the LCOALDIMMING backlight driving circuit also comprises a temperature sensing module used for collecting the temperature of the power bus switch, the temperature sensing module is arranged close to the power bus switch, and the output end of the temperature sensing module is connected with the input end of the signal processing module;
the signal processing module comprises a first resistor, a second resistor, a third resistor, a first electronic switch and a second capacitor, wherein a controlled end of the first electronic switch is an input end of the signal processing module and is connected with a first end of the first resistor, an input end of the first electronic switch is interconnected with a second direct-current power supply and a second end of the first resistor through the second resistor, and an output end of the first electronic switch is an output end of the signal processing module and is interconnected with a first end of the third resistor and a first end of the second capacitor; a second end of the third resistor and a second end of the second capacitor are both grounded;
the signal acquisition module comprises a plurality of signal acquisition branches, each signal acquisition branch comprises a coupling unit, a rectification unit and a low-pass filtering unit, the input end of the coupling unit is the input end of the signal acquisition branch, and the output end of the coupling unit is connected with the output end of the rectification unit; the output end of the rectification unit is the output end of the signal acquisition branch circuit and is connected with the input end of the low-pass filtering unit;
and the coupling unit is used for filtering the direct current signal in the square wave signal.
2. The lcoaldiming backlight driving circuit of claim 1, wherein the lcoaldiming backlight driving circuit further comprises a signal amplification module, the signal amplification module is serially disposed between the signal acquisition module and the signal processing module, and/or serially disposed between the temperature sensing module and the signal processing module.
3. The lcoal driver backlight circuit of claim 1, wherein the temperature sensing module comprises a thermistor and a voltage divider resistor, wherein a first end of the voltage divider resistor is connected to a first dc power supply, a second end of the voltage divider resistor is connected to the first end of the thermistor, and a second end of the thermistor is connected to ground.
4. The lcoal luminance driving circuit as claimed in claim 1, wherein the number of the plurality of signal collecting branches corresponds to the number corresponding to the power bus, and the input terminals of the plurality of signal collecting branches are connected to the power bus in a one-to-one correspondence; and the output ends of the signal acquisition branches are connected with the input ends of the signal processing module in a one-to-one correspondence manner.
5. The LCOALDIMMING backlight driving circuit of claim 4, wherein the coupling unit comprises a first capacitor, a first terminal of the first capacitor being an input terminal of the coupling unit, and a second terminal of the first capacitor being an output terminal of the coupling unit.
6. The lcoal luminance driving circuit as claimed in any one of claims 1 to 5, wherein the signal processing module comprises an operational amplifier and a control chip, wherein an input terminal of the operational amplifier is an input terminal of the signal processing module, and an output terminal of the operational amplifier is connected to an input terminal of the control chip; the output end of the control chip is the output end of the signal processing module.
7. A display device comprising the lcoaldiming backlight driving circuit of any one of claims 1 to 6.
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| CN201711427471.0A CN107863073B (en) | 2017-12-22 | 2017-12-22 | LCOALDIMMING backlight driving circuit and display device |
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| CN201711427471.0A CN107863073B (en) | 2017-12-22 | 2017-12-22 | LCOALDIMMING backlight driving circuit and display device |
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| CN107863073B true CN107863073B (en) | 2022-07-29 |
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| CN108665859B (en) * | 2018-08-01 | 2023-12-29 | 合肥惠科金扬科技有限公司 | Backlight source control circuit and backlight source |
| CN115424551A (en) * | 2022-08-25 | 2022-12-02 | 深圳市创元微电子科技有限公司 | Flat panel display detection method and device, electronic equipment and medium |
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