CN109272946B - Backlight source control circuit and liquid crystal display device - Google Patents
Backlight source control circuit and liquid crystal display device Download PDFInfo
- Publication number
- CN109272946B CN109272946B CN201811366972.7A CN201811366972A CN109272946B CN 109272946 B CN109272946 B CN 109272946B CN 201811366972 A CN201811366972 A CN 201811366972A CN 109272946 B CN109272946 B CN 109272946B
- Authority
- CN
- China
- Prior art keywords
- backlight
- control signal
- signal
- microcontroller
- resistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000004973 liquid crystal related substance Substances 0.000 title claims abstract description 21
- 238000002955 isolation Methods 0.000 claims abstract description 21
- 230000000007 visual effect Effects 0.000 claims description 6
- 239000003990 capacitor Substances 0.000 claims description 5
- 238000010586 diagram Methods 0.000 description 10
- 238000000034 method Methods 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000009499 grossing Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003071 parasitic effect Effects 0.000 description 2
- 230000005669 field effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—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
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—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
- G09G3/36—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 using liquid crystals
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
The invention provides a backlight source control circuit and a liquid crystal display device, comprising: the LED driver comprises a microcontroller, an LED driver and a logic module; the logic module comprises a voltage division unit and an isolation unit; the voltage division unit comprises a first resistor and a second resistor, and the isolation unit comprises a switching tube element and a pull-down resistor; the switching tube element comprises a control end, a first passage end and a second passage end. When the logic module receives an effective enabling signal, if the level of the wide-narrow viewing angle control signal received by the microcontroller changes, the level of the switch control signal received by the logic module also changes, so that the backlight control signal output by the logic module changes from effective to ineffective, and the LED driver stops driving the backlight source. The backlight source control circuit and the liquid crystal display device disclosed by the invention can control the backlight source to be closed when the wide and narrow viewing angles are switched, and meanwhile, an enabling signal cannot directly enter the microcontroller to generate current to cause the failure of the microcontroller.
Description
Technical Field
The invention relates to the technical field of liquid crystal display, in particular to a backlight source control circuit and a liquid crystal display device.
Background
Since the lcd has many advantages such as lightness, thinness, energy saving, low radiation, and no flicker, it is widely used in electronic devices such as tv, computer, mobile phone, and digital camera. Liquid crystal display devices currently on the market are mainly classified into three types: an In-Plane Switching (IPS) type, a Vertical Alignment (VA) type, and a Twisted Nematic (TN) type or a Super Twisted Nematic (STN) type. A Hybrid Viewing Angle (HVA) type is a liquid crystal display device improved on the basis of a planar conversion type. The HVA type liquid crystal display device is classified into a Wide Viewing Angle (WVA) mode and a Narrow Viewing Angle (NVA) mode.
When a user switches between wide and narrow viewing angle modes, the user needs to turn off the backlight source briefly to block an instable state at the moment of wide and narrow switching.
Fig. 1 shows a schematic structural diagram of a microcontroller in the prior art, as shown in fig. 1, in the prior art, on one hand, when a system power source Vin does not supply power and an enable signal EN supplies power for 3.3V, a supply voltage DVCC of the microcontroller is 0V, a diode inside the microcontroller is turned on, the enable signal EN may leak current to the microcontroller, which may affect the service life of the microcontroller for a long time, resulting in failure of the microcontroller; on the other hand, the voltage requirement of the input/output port of the microcontroller in the existing design scheme is not higher than the power supply voltage of the microcontroller by 0.3V, but the backlight module is lit up with different picture power consumptions and different line losses, and when the actual power supply voltage of the backlight module is lower (assumed to be 3.0V) and the voltage of the enable signal is maintained to be 3.3V, the voltage of the input/output port and the power supply voltage of the microcontroller may exceed 0.3V, which does not meet the specification requirement of the microcontroller and may bring unknown risks.
Disclosure of Invention
The invention mainly aims to provide a backlight source control circuit and a liquid crystal display device, which can close a backlight source when a wide and narrow viewing angle mode is switched, ensure that an enable signal cannot directly enter a microcontroller to generate leakage current, avoid the risk of failure of the microcontroller and improve the stability of the circuit.
In order to achieve the above object, a first aspect of embodiments of the present invention provides a backlight control circuit, including: the microcontroller comprises a wide and narrow visual angle control signal input end and a switch control signal output end; an LED driver including a backlight control signal input terminal; the logic module comprises a voltage division unit and an isolation unit; the voltage division unit comprises a first resistor and a second resistor, wherein a first end of the first resistor receives an enabling signal, and a second end of the first resistor is connected with a backlight enabling signal input end of the LED driver and is grounded through the second resistor; the isolation unit comprises a switching tube element and a pull-down resistor, the switching tube element comprises a control end, a first path end and a second path end, the control end of the switching tube element is connected with a switch control signal output end of the microcontroller, the first path end of the switching tube element is connected with the second end of the first resistor, the second path end of the switching tube element is grounded, and the pull-down resistor is positioned between the control end of the switching tube element and the ground; when the logic module receives an effective enabling signal, if the level of the wide-narrow viewing angle control signal received by the microcontroller changes, the level of the switch control signal received by the logic module also changes, so that the backlight control signal output by the logic module changes from effective to ineffective, and the LED driver stops driving the backlight source.
Further, if the enable signal is an active signal, the switch control signal is an inactive signal, the switch tube element is turned off, and the backlight enable signal is active and controls the backlight source to be turned on;
if the enable signal is an effective signal, the switch control signal is an effective signal, and the switch tube element is switched on, so that the backlight enable signal is invalid and the backlight source is controlled to be switched off.
Further, the effective signal is a high level signal or a low level signal.
Further, when the wide and narrow viewing angle control signal is converted, the switch control signal generates and maintains an effective signal of 100-.
Furthermore, the switch tube element is an NMOS tube or a PMOS tube or a triode.
Further, the switch control signal output end of the microcontroller is an input/output port.
Further, the backlight control circuit further includes: a third resistor between the switch control signal output and the switch tube element control terminal.
The backlight source control circuit further comprises a capacitor, and the capacitor is connected with the pull-down resistor in parallel.
Further, the backlight control circuit further includes a connector that provides the enable signal and the wide-narrow viewing angle control signal.
In addition, in order to achieve the above object, a second aspect of embodiments of the present invention provides a liquid crystal display device, which includes a backlight and the backlight control circuit according to the first aspect.
According to the backlight source control circuit and the liquid crystal display device, the logic module is arranged, so that the backlight source can be closed when the wide and narrow viewing angle modes are switched, the isolation unit is arranged on the logic module, and the switching tube element in the isolation unit can ensure that an enable signal cannot directly enter the microcontroller to generate leakage current, so that the failure of the microcontroller is avoided, and the unknown risk caused by low power supply voltage of the microcontroller under the conditions that the backlight module is lighted at different pictures, the power consumption is different, and the line loss is different is also ensured, so that the voltage of the input/output port of the microcontroller meets the requirements of specifications. In addition, the pull-down resistor in the isolation unit can not only provide a stable state for the switch tube element at the moment when the module is powered on, but also avoid the situation that the switch control signal output end of the microcontroller is coupled and pulled up due to the influence of the parasitic capacitance of the switch tube element, and ensure that the level of the switch tube control signal output port of the microcontroller is low level when the microcontroller does not work. Therefore, the invention greatly improves the stability of the backlight source controller circuit, thereby improving the quality of the liquid crystal display device.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.
FIG. 1 shows a schematic diagram of a prior art microcontroller;
FIG. 2 is a schematic diagram of a backlight control circuit according to a first embodiment of the invention;
fig. 3 shows a logic timing diagram of signals in the backlight control circuit shown in fig. 2 when switching between wide and narrow viewing angles is performed according to the first embodiment;
FIG. 4 is a schematic diagram of a backlight control circuit according to a second embodiment of the present disclosure;
fig. 5 shows a logic timing diagram of signals in the backlight control circuit shown in fig. 4 when switching between wide and narrow viewing angles is performed in the second embodiment.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. Moreover, certain well-known elements may not be shown in the figures.
In the following description, numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of the devices are described in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.
First embodiment
Fig. 2 shows a schematic structural diagram of a backlight control circuit according to a first embodiment of the present invention, and fig. 3 shows a logic timing diagram of signals in the backlight control circuit shown in fig. 2 according to the first embodiment when switching between wide and narrow viewing angles, and as shown in fig. 2, the backlight control circuit according to the present invention includes a microcontroller 11, an LED driver 12, and a logic module 13. The microcontroller 11 comprises a wide and narrow viewing angle control signal input end and a switch control signal output end P1.1. The LED driver 12 comprises a backlight control signal input. The logic module 13 includes a voltage dividing unit 131 and an isolating unit 132.
Specifically, the voltage dividing unit 131 includes a first resistor R1 and a second resistor R2, a first end of the first resistor R1 receives the enable signal EN, a second end of the first resistor R1 is connected to the backlight control signal input end of the LED driver, and is grounded through the second resistor R2.
Specifically, the isolation unit 132 includes a switching tube element T1, a pull-down resistor R4. The switching tube element T1 includes a control terminal, a first path terminal and a second path terminal, the control terminal of the switching tube element T1 is connected to the switch control signal output terminal of the microcontroller 11, the first path terminal of the switching tube element T1 is connected to the second terminal of the first resistor R1, the second path terminal of the switching tube element T1 is grounded, and the pull-down resistor R4 is located between the control terminal of the switching tube element T1 and the ground.
In the present embodiment, the switching transistor element T1 is preferably an N-channel field effect transistor, i.e., an NMOS transistor. However, the embodiments of the present invention are not limited thereto, and those skilled in the art can determine the type of the switching tube element and adjust the level of the corresponding signal accordingly.
When the logic module 13 receives the valid enable signal EN, if the level of the wide and narrow viewing angle control signal HVA received by the microcontroller 11 changes, the level of the switch control signal EN _ M received by the logic module 13 also changes, so that the backlight control signal EN _ L output by the logic module 13 changes from valid to invalid, and the LED driver stops driving the backlight source.
In this embodiment, if the enable signal EN is an active signal and the switch control signal EN _ M is an inactive signal, the switching tube element T1 is turned off and the backlight enable signal EN _ L is active and controls the backlight source to be turned on;
if the enable signal EN is an active signal and the switch control signal EN _ M is an active signal, the switching tube element T1 is turned on to disable the backlight enable signal EN _ L and control the backlight source to be turned off.
The valid signal in the present invention may be a high level signal or a low level signal depending on the type of the LED driver 12 and the switching tube element T1.
For better understanding of the present invention, the following description will be made with reference to fig. 3, and by taking the switching transistor element T1 as an NMOS transistor, the enable signal EN is active high, and the backlight enable signal EN _ L is also active high.
At time a, when the power voltage Vin is powered on, the enable signal EN is at a high level, and the level of the wide-narrow viewing angle control signal HVA is not changed (the wide-narrow viewing angle is not switched), the switch control signal EN _ M output by the switch control signal output end P1.1 of the microcontroller 11 is at a low level, so that the NMOS transistor T1 is turned off, the backlight enable signal EN _ L is pulled high by the enable signal EN through the first resistor R1, and the LED driver 12 drives the backlight, so that the backlight is in an on state.
At time B, when the level of the narrow-viewing angle control signal HVA changes (the narrow-viewing angle is switched), for example, as shown in fig. 3, the level changes from low to high, the switch control signal EN _ M output by the switch control signal output terminal P1.1 of the microcontroller 11 is high and is maintained for 100-plus-200 ms, and further the NMOS transistor T1 is turned on, the backlight enable signal EN _ L is pulled down through the turned-on NMOS transistor T1, the LED driver 12 stops driving the backlight, and the backlight is turned off;
at time C, the wide-narrow viewing angle control signal HVA is maintained at a high level (without conversion), the switch control signal output terminal P1.1 of the microcontroller 11 outputs the switch control signal EN _ M at a low level again, the NMOS transistor T1 is turned off again, the backlight enable signal EN _ L is restored to a high level, the LED driver 12 drives the backlight again, and the backlight is turned on again.
In addition, when the logic module 13 receives the inactive enable signal EN, the switching tube element T1 receives the inactive backlight enable signal EN _ L regardless of whether it is turned on or off (i.e., regardless of whether the switching of the wide and narrow viewing angles is performed), and the backlight is always in the off state.
In the present embodiment, the switch control signal output terminal P1.1 of the microcontroller 11 is an input/output port, and in the present embodiment, the pin P1.1 is preferably selected as the switch control signal output terminal, and the default output is a low level.
When the wide and narrow viewing angle control signal HVA is changed, the switch control signal EN _ M generates and maintains a high level signal of 100-. When the wide-narrow viewing angle control signal HVA is not converted, the P1.1 port signal of the microcontroller 11 is restored to the low level again, so that the NMOS transistor T1 is turned off, the backlight control signal EN _ L is at the high level, and the LED driver 12 continues to drive the backlight. Therefore, the backlight source driving circuit can close the backlight source when the wide and narrow visual angle modes are switched, and can normally open the backlight source when the wide and narrow visual angle modes are not switched, so that the normal work of the liquid crystal display device is ensured. In addition, the NMOS transistor T1 of the switch tube element in the isolation unit 132 isolates the enable signal EN from the microcontroller 11, so as to avoid the occurrence of leakage current to the microcontroller 11 caused by the enable signal EN, and avoid the unknown risk caused by the fact that the actual power voltage Vin of the backlight module is lower than the voltage at the switch control signal output terminal P1.1 of the microcontroller 11 due to different power consumptions of different pictures of the backlight module. In addition, because the pull-down resistor R4 of the invention is connected to the control terminal of the NMOS transistor T1 and the ground, the situation that the switch control signal output terminal P1.1 of the microcontroller 11 is coupled and pulled up due to the influence of the inter-electrode capacitance of the switching transistor element T1 is avoided, the level of the switch control signal output terminal P1.1 is further ensured to be low when the microcontroller 11 does not work, and the situation that the voltage of the switch control signal output terminal P1.1 is higher than the supply voltage DVCC of the microcontroller 11 is further ensured not to occur even if the switch control signal output terminal P1.1 is an input/output port.
The backlight control circuit in this embodiment may further include a third resistor R3, which is located between the switch control signal output terminal and the control terminal of the NMOS transistor T1, and is used to limit the current flowing between the switch control signal output terminal and the control terminal of the NMOS transistor T1.
The backlight control circuit further comprises a capacitor C1, which is located between the common node of the third resistor R3 and the pull-down resistor R4 and the ground, for reducing the ac ripple factor and smoothing the dc output.
In one embodiment, the backlight control circuit further includes a connector 10, and the enable signal EN, the wide-narrow viewing angle control signal HVA and the power supply voltage DVCC are provided by the connector 10.
In one embodiment, the supply voltage DVCC port of the microcontroller 11 is connected to the Vin port of the connector 10.
The backlight control circuit provided by the embodiment of the invention can close the backlight when the wide and narrow viewing angle modes are switched by arranging the logic module 13 and the connection mode of the logic module 13 with the microcontroller 11 and the LED driver 12, meanwhile, the logic module 13 is provided with the isolation unit 132, and a switching tube element T1 in the isolation unit 132 can ensure that an enable signal EN can not directly enter the microcontroller 11 to generate leakage current, so that the failure of the microcontroller 11 is avoided, and the unknown risk caused by low power supply voltage Vin input into the microcontroller 11 can be ensured under the conditions that the backlight module is lighted at different pictures with different power consumptions and different line losses, so that the voltage of an input/output port P1.1 of the microcontroller 11 meets the requirements of specifications. In addition, the pull-down resistor R4 in the isolation unit 132 not only can provide a stable state for the switching tube element T1 at the moment when the backlight driving circuit is powered on, but also can avoid the situation that the switching control signal output port P1.1 of the microcontroller 11 is coupled and pulled high due to the influence of the inter-electrode capacitance of the switching tube element T1, thereby ensuring that the level of the switching tube control signal output port P1.1 is low when the microcontroller 11 does not operate. Therefore, the stability of the backlight source control circuit is greatly improved, and the quality of the liquid crystal display device is further improved.
Second embodiment
Fig. 4 is a schematic structural diagram of a backlight control circuit according to a second embodiment of the present invention, and fig. 5 is a logic timing diagram of signals in the backlight control circuit shown in fig. 4 according to the second embodiment when the wide and narrow viewing angles are switched, as shown in fig. 4, the backlight control circuit in this embodiment is substantially the same as the backlight control circuit in the first embodiment, except that the switching transistor element T1 in this embodiment is a PMOS transistor, and the default output level of the switching control signal output terminal P1.1 of the microcontroller 11 is a high level.
In the present embodiment, the switching transistor device T1 is a P-channel fet, i.e. a PMOS transistor. However, the embodiments of the present invention are not limited thereto, and those skilled in the art can determine the type of the switching tube element and adjust the level of the corresponding signal accordingly.
When the logic module 13 receives the valid enable signal EN, if the level of the wide and narrow viewing angle control signal HVA received by the microcontroller 11 changes, the level of the switch control signal EN _ M received by the logic module 13 also changes, so that the backlight control signal EN _ L output by the logic module 13 changes from valid to invalid, and the LED driver stops driving the backlight source.
In this embodiment, if the enable signal EN is an active signal and the switch control signal EN _ M is an inactive signal, the switching tube element T1 is turned off and the backlight enable signal EN _ L is active and controls the backlight source to be turned on;
if the enable signal EN is an active signal and the switch control signal EN _ M is an active signal, the switching tube element T1 is turned on to disable the backlight enable signal EN _ L and control the backlight source to be turned off.
The valid signal in the present invention may be a high level signal or a low level signal depending on the type of the LED driver 12 and the switching tube element T1.
For better understanding of the present invention, the following description will be made with reference to fig. 5, and by taking the switching transistor element T1 as a PMOS transistor, the enable signal EN is active high, and the backlight enable signal EN _ L is also active high.
At time a, when the power voltage Vin is powered on, the enable signal EN is at a high level, and the level of the wide-narrow viewing angle control signal HVA is not changed (the wide-narrow viewing angle is not switched), the switch control signal EN _ M output by the switch control signal output end P1.1 of the microcontroller 11 is at a high level, so that the PMOS transistor T1 is turned off, the backlight enable signal EN _ L is pulled high by the enable signal EN through the first resistor R1, and the LED driver 12 drives the backlight, so that the backlight is in an on state.
At time B, when the level of the narrow-viewing angle control signal HVA changes (the narrow-viewing angle is switched), for example, as shown in fig. 5, the level changes from low to high, the switch control signal EN _ M output by the switch control signal output terminal P1.1 of the microcontroller 11 is low and is maintained for 100-plus-200 ms, and further the PMOS transistor T1 is turned on, the backlight enable signal EN _ L is pulled down through the turned-on PMOS transistor T1, the LED driver 12 stops driving the backlight, and the backlight is turned off;
at time C, the wide-narrow viewing angle control signal HVA is maintained at a high level (without conversion), the switch control signal output terminal P1.1 of the microcontroller 11 outputs the switch control signal EN _ M at the high level again, the PMOS transistor T1 is turned off again, the backlight enable signal EN _ L is restored to the high level, the LED driver 12 drives the backlight again, and the backlight is turned on again.
In addition, when the logic module 13 receives the inactive enable signal EN, the switching tube element T1 receives the inactive backlight enable signal EN _ L regardless of whether it is turned on or off (i.e., regardless of whether the switching of the wide and narrow viewing angles is performed), and the backlight is always in the off state.
In the present embodiment, the switch control signal output terminal P1.1 of the microcontroller 11 is an input/output port, and in the present embodiment, the pin P1.1 is preferably selected as the switch control signal output terminal, and the default output is a low level.
When the wide-narrow viewing angle control signal HVA is changed, the switch control signal EN _ M generates and maintains a low level signal of 100-. When the wide-narrow viewing angle control signal HVA is not converted, the P1.1 port signal of the microcontroller 11 is restored to the high level again, so that the PMOS transistor T1 is turned off, the backlight control signal EN _ L is at the high level, and the LED driver 12 continues to drive the backlight. Therefore, the backlight source driving circuit can close the backlight source when the wide and narrow visual angle modes are switched, and can normally open the backlight source when the wide and narrow visual angle modes are not switched, so that the normal work of the liquid crystal display device is ensured. In addition, the PMOS transistor T1 in the isolation unit 132 isolates the enable signal EN from the microcontroller 11, so as to avoid leakage current generated by the enable signal EN to the microcontroller 11, and avoid unknown risk caused by the fact that the actual power voltage Vin of the backlight module is lower than the voltage at the switch control signal output terminal P1.1 of the microcontroller 11 due to different power consumptions of different pictures of the backlight module caused by different line losses. In addition, because the pull-down resistor R4 of the invention is connected to the control terminal of the PMOS transistor T1 and the ground, the situation that the switching control signal output terminal P1.1 of the microcontroller 11 is coupled and pulled up due to the influence of the inter-electrode capacitance of the switching transistor element T1 is avoided, the level of the switching control signal output terminal P1.1 is further ensured to be low when the microcontroller 11 does not work, and the situation that the voltage of the switching control signal output terminal P1.1 is higher than the supply voltage DVCC of the microcontroller 11 is further ensured not to occur even if the switching control signal output terminal P1.1 is an input/output port.
The backlight control circuit in this embodiment may further include a third resistor R3, which is disposed between the switch control signal output terminal and the control terminal of the switch transistor PMOS transistor T1, for limiting the current flowing between the switch control signal output terminal and the control terminal of the switch transistor PMOS transistor T1.
The backlight control circuit further comprises a capacitor C1, which is located between the common node of the third resistor R3 and the pull-down resistor R4 and the ground, for reducing the ac ripple factor and smoothing the dc output.
In one embodiment, the backlight control circuit further includes a connector 10, and the enable signal EN, the wide-narrow viewing angle control signal HVA and the power supply voltage DVCC are provided by the connector 10.
In one embodiment, the supply voltage DVCC port of the microcontroller 11 is connected to the Vin port of the connector 10.
The backlight control circuit provided by the embodiment of the invention can close the backlight when the wide and narrow viewing angle modes are switched by arranging the logic module 13 and the connection mode of the logic module 13 with the microcontroller 11 and the LED driver 12, meanwhile, the logic module 13 is provided with the isolation unit 132, and a switching tube element T1 in the isolation unit 132 can ensure that an enable signal EN can not directly enter the microcontroller 11 to generate leakage current, so that the failure of the microcontroller 11 is avoided, and the unknown risk caused by low power supply voltage Vin input into the microcontroller 11 can be ensured under the conditions that the backlight module is lighted at different pictures with different power consumptions and different line losses, so that the voltage of an input/output port P1.1 of the microcontroller 11 meets the requirements of specifications. In addition, the pull-down resistor R4 in the isolation unit 132 not only can provide a stable state for the switching tube element T1 at the moment when the backlight driving circuit is powered on, but also can avoid the situation that the switching control signal output port P1.1 of the microcontroller 11 is coupled and pulled high due to the influence of the inter-electrode capacitance of the switching tube element T1, thereby ensuring that the level of the switching tube control signal output port P1.1 is low when the microcontroller 11 does not operate. Therefore, the stability of the backlight source control circuit is greatly improved, and the quality of the liquid crystal display device is further improved.
Third embodiment
The third embodiment of the present invention provides a liquid crystal display device, which includes a backlight source control module and a backlight source. The structure and the working principle of the backlight control module please refer to the description of the backlight control module, which is not repeated herein.
According to the backlight source control circuit and the liquid crystal display device provided by the invention, the logic module 13 and the connection mode of the logic module 13 and the microcontroller 11 and the LED driver 12 are arranged, so that the backlight source can be closed when the wide and narrow viewing angle modes are switched, meanwhile, the logic module 13 is provided with the isolation unit 132, and a switching tube element T1 in the isolation unit 132 can ensure that an enable signal EN can not directly enter the microcontroller 11 to generate leakage current, so that the failure of the microcontroller 11 is avoided, and the unknown risk caused by low power supply voltage Vin input into the microcontroller 11 can be ensured under the conditions that the backlight module is lighted at different pictures with different power consumptions and different line losses, so that the voltage of an input/output port P1.1 of the microcontroller 11 meets the requirements of specifications. In addition, the pull-down resistor R4 in the isolation unit 132 not only can provide a stable state for the switch tube element at the moment when the module is powered on, but also can avoid the situation that the switch control signal output port P1.1 of the microcontroller 11 is coupled and pulled high due to the influence of the parasitic capacitance of the switch tube element T1, thereby ensuring that the level of the switch tube control signal output port P1.1 is low when the microcontroller 11 does not work. Therefore, the stability of the backlight source control circuit is greatly improved, and the quality of the liquid crystal display device is further improved.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
While embodiments in accordance with the invention have been described above, these embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.
Claims (10)
1. A backlight control circuit, comprising:
the microcontroller comprises a wide and narrow visual angle control signal input end and a switch control signal output end;
an LED driver including a backlight control signal input terminal;
the logic module comprises a voltage division unit and an isolation unit;
the voltage division unit comprises a first resistor and a second resistor, wherein a first end of the first resistor receives an enabling signal, and a second end of the first resistor is connected with a backlight enabling signal input end of the LED driver and is grounded through the second resistor;
the isolation unit comprises a switching tube element and a pull-down resistor, the switching tube element comprises a control end, a first path end and a second path end, the control end of the switching tube element is connected with a switch control signal output end of the microcontroller, the first path end of the switching tube element is connected with the second end of the first resistor, the second path end of the switching tube element is grounded, and the pull-down resistor is positioned between the control end of the switching tube element and the ground;
when the logic module receives an effective enabling signal, if the level of the wide-narrow viewing angle control signal received by the microcontroller changes, the level of the switch control signal received by the logic module is firstly changed from effective to ineffective, so that the backlight control signal output by the logic module is changed from effective to ineffective, the LED driver stops driving the backlight source, and then is changed from ineffective to effective, so that the backlight control signal output by the logic module is changed from ineffective to effective, and the LED driver continues to drive the backlight source.
2. The backlight control circuit of claim 1,
if the enabling signal is an effective signal, the switch control signal is an ineffective signal, the switch tube element is closed, the backlight enabling signal is effective, and the backlight source is controlled to be opened;
if the enable signal is an effective signal, the switch control signal is an effective signal, and the switch tube element is switched on, so that the backlight enable signal is invalid and the backlight source is controlled to be switched off.
3. The backlight control circuit of claim 2, wherein the active signal is a high signal or a low signal.
4. The backlight control circuit of claim 2,
when the wide and narrow viewing angle control signal is converted, the switch control signal generates and maintains an effective signal of 100-.
5. The backlight control circuit of claim 1,
the switch tube element is an NMOS tube or a PMOS tube or a triode.
6. The backlight control circuit of claim 1,
and the switch control signal output end of the microcontroller is an input/output port.
7. The backlight control circuit of claim 1, further comprising: a third resistor between the switch control signal output and the switch tube element control terminal.
8. The backlight control circuit of claim 7, further comprising a capacitor between a common node of the third resistor and the pull-down resistor and ground.
9. The backlight control circuit of claim 1, further comprising a connector that provides the enable signal and the wide-narrow viewing angle control signal.
10. A liquid crystal display device, comprising:
the backlight control circuit and the backlight according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811366972.7A CN109272946B (en) | 2018-11-16 | 2018-11-16 | Backlight source control circuit and liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811366972.7A CN109272946B (en) | 2018-11-16 | 2018-11-16 | Backlight source control circuit and liquid crystal display device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109272946A CN109272946A (en) | 2019-01-25 |
| CN109272946B true CN109272946B (en) | 2020-06-05 |
Family
ID=65190365
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811366972.7A Active CN109272946B (en) | 2018-11-16 | 2018-11-16 | Backlight source control circuit and liquid crystal display device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109272946B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111026234A (en) * | 2019-11-21 | 2020-04-17 | Tcl华星光电技术有限公司 | Display and desktop computer |
| CN111028793B (en) * | 2020-01-06 | 2021-10-15 | 昆山龙腾光电股份有限公司 | Electronic equipment and backlight brightness adjusting method |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1847957A (en) * | 2005-04-04 | 2006-10-18 | 日本电气株式会社 | Planar light source device, display device, terminal device, and method for driving planar light source device |
| CN1932593A (en) * | 2005-09-14 | 2007-03-21 | 日本电气株式会社 | Light source device, display device, terminal device, light source unit, and method for driving light source device |
| CN102323684A (en) * | 2011-09-10 | 2012-01-18 | 鞍山亚世光电显示有限公司 | Wide-angle SMT (surface mounted technology) liquid crystal display module |
| CN202205441U (en) * | 2011-08-03 | 2012-04-25 | 青岛海信电器股份有限公司 | Backlight control circuit, backlight lighting device, and LED liquid crystal display device |
| CN103218976A (en) * | 2013-03-05 | 2013-07-24 | 深圳市华星光电技术有限公司 | Light-emitting diode (LED) backlight driving circuit, LED backlight and liquid crystal display |
| CN104330997A (en) * | 2013-07-22 | 2015-02-04 | 深圳光启创新技术有限公司 | Time-delay control circuit and time-delay control system |
| CN105810154A (en) * | 2016-05-09 | 2016-07-27 | 昆山龙腾光电有限公司 | LED back light module, display device and LED back light driving method |
| CN106023908A (en) * | 2016-07-25 | 2016-10-12 | 昆山龙腾光电有限公司 | Backlight driving circuit and backlight control method for liquid crystal display device |
| CN206097873U (en) * | 2016-09-28 | 2017-04-12 | 昆山龙腾光电有限公司 | Anti -reverse connection circuit and backlight drive device |
| CN106814502A (en) * | 2015-11-27 | 2017-06-09 | 扬升照明股份有限公司 | Backlight module, driving method thereof and display device with backlight module |
| CN206948664U (en) * | 2017-06-20 | 2018-01-30 | 昆山龙腾光电有限公司 | Led drive circuit and liquid crystal display device |
| CN207397675U (en) * | 2017-11-14 | 2018-05-22 | 昆山龙腾光电有限公司 | Width view angle switch circuit and display device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5382498B2 (en) * | 2008-11-10 | 2014-01-08 | Ｎｌｔテクノロジー株式会社 | Liquid crystal display device, liquid crystal display control device, electronic device, and driving method of liquid crystal display device |
-
2018
- 2018-11-16 CN CN201811366972.7A patent/CN109272946B/en active Active
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1847957A (en) * | 2005-04-04 | 2006-10-18 | 日本电气株式会社 | Planar light source device, display device, terminal device, and method for driving planar light source device |
| CN1932593A (en) * | 2005-09-14 | 2007-03-21 | 日本电气株式会社 | Light source device, display device, terminal device, light source unit, and method for driving light source device |
| CN202205441U (en) * | 2011-08-03 | 2012-04-25 | 青岛海信电器股份有限公司 | Backlight control circuit, backlight lighting device, and LED liquid crystal display device |
| CN102323684A (en) * | 2011-09-10 | 2012-01-18 | 鞍山亚世光电显示有限公司 | Wide-angle SMT (surface mounted technology) liquid crystal display module |
| CN103218976A (en) * | 2013-03-05 | 2013-07-24 | 深圳市华星光电技术有限公司 | Light-emitting diode (LED) backlight driving circuit, LED backlight and liquid crystal display |
| CN104330997A (en) * | 2013-07-22 | 2015-02-04 | 深圳光启创新技术有限公司 | Time-delay control circuit and time-delay control system |
| CN106814502A (en) * | 2015-11-27 | 2017-06-09 | 扬升照明股份有限公司 | Backlight module, driving method thereof and display device with backlight module |
| CN105810154A (en) * | 2016-05-09 | 2016-07-27 | 昆山龙腾光电有限公司 | LED back light module, display device and LED back light driving method |
| CN106023908A (en) * | 2016-07-25 | 2016-10-12 | 昆山龙腾光电有限公司 | Backlight driving circuit and backlight control method for liquid crystal display device |
| CN206097873U (en) * | 2016-09-28 | 2017-04-12 | 昆山龙腾光电有限公司 | Anti -reverse connection circuit and backlight drive device |
| CN206948664U (en) * | 2017-06-20 | 2018-01-30 | 昆山龙腾光电有限公司 | Led drive circuit and liquid crystal display device |
| CN207397675U (en) * | 2017-11-14 | 2018-05-22 | 昆山龙腾光电有限公司 | Width view angle switch circuit and display device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109272946A (en) | 2019-01-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10101842B2 (en) | Method for driving touch display apparatus and touch display apparatus | |
| US20180024677A1 (en) | Touch display driving integrated circuit and operation method thereof | |
| TWI415094B (en) | Liquid crystal display device | |
| US8674975B2 (en) | Liquid crystal display and driving method with common voltage control for avoiding flicker and color-shift phenomena | |
| TWI596595B (en) | Display apparatus and driving method of display panel thereof | |
| US20120146936A1 (en) | Liquid crystal display having touch sensing functionality and touch sensing method thereof | |
| CN105513549A (en) | Circuit for eliminating shutdown afterimage of liquid crystal display device and liquid crystal display device using same | |
| KR102271488B1 (en) | Voltage supply unit and display device including the same | |
| KR20080048325A (en) | Power generation unit for liquid crystal display device | |
| CN108172179B (en) | Power management circuit | |
| TWI514364B (en) | Liquid crystal pixel circuit of liquid crystal display panel and driving method thereof | |
| US7696646B2 (en) | Power switching circuit for liquid crystal display | |
| CN106847215B (en) | Display device | |
| TW201931089A (en) | Display device including touch sensor | |
| CN109461415B (en) | Display panel's drive circuit and display panel | |
| CN109272946B (en) | Backlight source control circuit and liquid crystal display device | |
| CN108415633B (en) | Touch display screen and touch display device | |
| TWI469128B (en) | Voltage calibration circuit and related liquid crystal display device | |
| WO2020113677A1 (en) | Display panel driving device | |
| CN109509449B (en) | Current regulating circuit, driving circuit and display device | |
| US11176857B2 (en) | Display panel testing apparatus and testing method | |
| JP3737006B2 (en) | Method for reducing residual image on liquid crystal display | |
| TWI404032B (en) | Liquid crystal display device connecting external image signal source | |
| CN109271054B (en) | Touch display driving circuit | |
| CN214203168U (en) | Liquid crystal display device having a plurality of pixel electrodes |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| CB02 | Change of applicant information | ||
| CB02 | Change of applicant information |
Address after: 215301, 1, Longteng Road, Kunshan, Jiangsu, Suzhou Applicant after: InfoVision Optoelectronics(Kunshan)Co.,Ltd. Address before: 215301, 1, Longteng Road, Kunshan, Jiangsu, Suzhou Applicant before: INFOVISION OPTOELECTRONICS (KUNSHAN) Co.,Ltd. |
|
| GR01 | Patent grant | ||
| GR01 | Patent grant |