CN114495844A - Dimming circuit, backlight control system and display device of LED - Google Patents
Dimming circuit, backlight control system and display device of LED Download PDFInfo
- Publication number
- CN114495844A CN114495844A CN202210111729.0A CN202210111729A CN114495844A CN 114495844 A CN114495844 A CN 114495844A CN 202210111729 A CN202210111729 A CN 202210111729A CN 114495844 A CN114495844 A CN 114495844A
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- voltage
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- dimming
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- operational amplifier
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—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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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
Abstract
The invention discloses a dimming circuit of an LED, a backlight control system and a display device thereof, wherein the dimming circuit of the LED comprises a voltage generation module for providing dimming voltage; and the voltage conversion current module is connected with the voltage adjustment module, converts the dimming voltage into dimming current and outputs the dimming current, and the resistance parameters in the voltage generation module and/or the voltage conversion current module are adjusted to improve the precision of the dimming current. The invention solves the problem of the reduction of the precision of the dimming current output by the dimming circuit caused by the influence of the component preparation process by adjusting the resistance parameters in the voltage generation module and/or the voltage conversion current module.
Description
Technical Field
The disclosure relates to the technical field of LED driving, in particular to a dimming circuit of an LED, a backlight control system and a display device thereof.
Background
The LED (Light Emitting Diode) has the characteristics of energy saving, environmental protection, high efficiency, long service life and the like, and is widely applied to the fields of illumination, display and the like. A DC dimming mode and/or a PWM dimming mode are often used to drive the LED display.
In order to obtain more excellent display visual effects, it is necessary to provide the LEDs with a dimming current with higher accuracy. In the existing conversion circuit for converting input voltage into output current in the analog circuit, the conversion precision is reduced under the influence of the preparation process of components in the conversion circuit, and the display effect of an LED cannot be further met.
Disclosure of Invention
In order to solve the technical problem, the present disclosure provides a dimming circuit of an LED, a backlight control system and a display device thereof.
According to a first aspect of the present disclosure, there is provided a dimming circuit of an LED, comprising:
a voltage generation module providing a dimming voltage; and
a voltage conversion current module connected with the voltage adjustment module for converting the dimming voltage into dimming current and outputting the dimming current,
wherein a resistance parameter in the voltage generation module and/or the voltage conversion current module is adjusted to improve the precision of the dimming current.
Optionally, the voltage generation module adjusts a resistance parameter to adjust the dimming voltage, and the precision of the dimming current obtained by conversion based on the adjusted dimming voltage is improved.
Optionally, the voltage generation module further adjusts the dimming voltage according to a digital signal.
Optionally, the voltage conversion current module adjusts a resistance parameter to compensate a conversion coefficient of the voltage conversion current module, and improves the precision of the dimming current obtained based on the compensated conversion coefficient, where the conversion coefficient is related to an electrical parameter of the device.
Optionally, the voltage generation module includes:
the voltage adjusting unit adjusts self resistance parameters to provide adjustable reference voltage; and
and the digital-to-analog converter is connected with the voltage adjusting unit and outputs the dimming voltage based on the reference voltage and the digital signal.
Optionally, the voltage adjusting unit includes:
a current source providing a reference current; and
and the first resistor is connected with the current source in series, and the resistance value of the first resistor is related to the target dimming current, the reference current and the conversion coefficient of the voltage conversion current module.
Optionally, the digital signal is editable.
Optionally, the voltage adjusting unit further includes:
and the first input end of the first operational amplifier is connected with the connection node of the current source and the first resistor, the second input end of the first operational amplifier is connected with the output end of the first operational amplifier, and the output end of the first operational amplifier outputs the reference voltage.
Optionally, the voltage-to-current conversion module comprises:
the operational amplifier unit is connected with the voltage adjusting module, compensates a conversion coefficient by adjusting self resistance parameters, and generates an intermediate current based on the dimming voltage; and
and the current mirror is connected with the operational amplifier unit and provides the dimming current proportional to the intermediate current.
Optionally, the operational amplifier unit includes:
the first input end of the second operational amplifier receives the dimming voltage, and the output end of the second operational amplifier outputs an intermediate voltage;
a first transistor, a control terminal of which receives the intermediate voltage, a first terminal of which is connected to a second input terminal of the second operational amplifier, and a second terminal of which outputs the intermediate current;
a second resistor having a first terminal connected to the first terminal of the first transistor and a second terminal connected to ground,
the resistance value of the second resistor is adjustable, and is related to the target dimming current, the reference current and electrical parameters of other components in the voltage conversion current module.
According to a second aspect of the present disclosure, there is provided a backlight control system comprising a dimming circuit of the LED.
According to a third aspect of the present disclosure, there is provided a display device comprising the backlight control system.
In the present disclosure, the precision of the dimming current is improved by adjusting the resistance parameter in the voltage generation module and/or the voltage conversion current module, so as to compensate for the amount of deviation occurring on the basis of the target conversion coefficient due to the influence of the device manufacturing process in the module on the conversion coefficient of the dimming voltage to the dimming current in the voltage conversion current module. The dimming circuit provided by the disclosure can solve the technical problem of dimming current precision reduction caused by a component preparation process in the circuit structure without changing the circuit structure.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Drawings
Fig. 1 shows a schematic structure diagram of a dimming circuit of an LED provided according to an embodiment of the present disclosure;
fig. 2 shows a circuit schematic of a dimming circuit for an LED provided in accordance with an embodiment of the present disclosure;
fig. 3 shows a further circuit schematic diagram of a dimming circuit for an LED provided according to an embodiment of the present disclosure.
Detailed Description
To facilitate an understanding of the present disclosure, the present disclosure will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present disclosure are set forth in the accompanying drawings. However, the present disclosure may be embodied in different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Fig. 1 shows a schematic structure diagram of a dimming circuit of an LED provided according to an embodiment of the present disclosure. Referring to fig. 1, a dimming circuit 1000 of an LED includes a voltage generation module 1100 and a voltage conversion current module 1200. The voltage generation module 1100 is used to provide the dimming voltage Vset. The voltage conversion current module 1200 is connected to the voltage adjustment module 1100, and is used for converting the dimming voltage Vset into a dimming current Idim for driving an LED display, for example, and outputting the dimming current Idim. The electrical parameters of the components in the dimming voltage conversion current module 1200 are converted by the dimming voltage such that the dimming voltage Vset is converted into the target dimming current based on the conversion coefficient. In practical situations, electrical parameters of at least some components in the voltage-to-current conversion module 1200 are affected by the manufacturing process, so that the conversion coefficient is shifted. The dimming circuit 1000 in the present disclosure adjusts the resistance parameter in the voltage generation module 1100 and/or the voltage conversion current module 1200 to improve the precision of the dimming current Idim.
In one embodiment, by adjusting the resistance parameter in the voltage generation module 1100 to adjust the dimming voltage Vset, the precision of the dimming current Idim converted based on the adjusted dimming voltage Vset is improved. Further, the voltage generation module 1100 also adjusts the dimming voltage Vset according to the digital signal data.
Further, the voltage generation module 1100 includes a voltage adjustment unit 1110 and a digital-to-analog converter 1120. The voltage adjustment unit 1110 adjusts its own resistance parameter to provide an adjustable reference voltage Vref. The digital-to-analog converter 1120 is connected to the voltage adjusting unit 1110, and outputs the dimming voltage Vset based on the reference voltage Vref and the digital signal data.
In another embodiment, the accuracy of the dimming current Idim obtained based on the compensated conversion coefficient is improved by adjusting the resistance parameter of the voltage conversion current module 1200 itself to compensate the conversion coefficient thereof, and the conversion coefficient is related to the electrical parameter of the device thereof. Further, the voltage-to-current conversion module 1200 includes an operational amplifier unit and a current mirror. The operational amplifier unit is connected with the voltage adjusting module, compensates the conversion coefficient by adjusting the self resistance parameter, and provides the intermediate current based on the dimming voltage Vset. The current mirror is connected to the operational amplifier unit and provides a dimming current Idim proportional to the intermediate current.
Fig. 2 shows a circuit schematic diagram of a dimming circuit of an LED provided according to an embodiment of the present disclosure. Referring to fig. 2, the dimming circuit 2000 includes a voltage generation module 2100 and a voltage conversion current module 2200. The voltage generation module 2100 includes a voltage adjustment unit 2110 and a digital-to-analog converter 2120. The voltage-to-current module 2200 includes an op-amp unit 2210 and a current mirror 2220.
The voltage adjusting unit 2110 includes a current source I1 and a first resistor R1. Current source I1 provides a reference current Iref. The first resistor R1 is a variable resistor and is connected between the current source I1 and ground. The resistance of the first resistor R1 is related to the target dimming current, the reference current Iref, and the conversion coefficient of the voltage conversion current module 1200 in the dimming circuit 2000. Further, the circuit also comprises a first operational amplifier U1, wherein a first input end is connected with a connection node of a current source I1 and a first resistor R1, a second input end is connected with an output end, and the output end outputs a reference voltage Vref. The output end of the first operational amplifier U1 is connected to the second input end (inverting input end) to form a buffer, and the reference voltage Vref output by the output end of the first operational amplifier U1 is Iref × R1+ Vos 1. Where Vos1 refers to the offset voltage of the first operational amplifier U1. The buffer has infinite input impedance and small output impedance, and can improve the driving capability of the output reference voltage Vref.
The dac 2120 is connected to the voltage adjusting unit 2110 for receiving the reference voltage Vref and receiving the data signal data. The data signal data can be edited, so that the current range of the dimming current Idim converted according to the dimming voltage Vset is larger, and more dimming requirements can be met. The data signal data is, for example, an eight-bit binary number. The dac 2120 is used for controlling the corresponding analog electronic switch according to the value of each digit in the digital signal data, and generating a current value proportional to the digit weight of the digit with a value of 1 on the digit weight network, summing the current values by the operational amplifier, and converting the summed current values into the dimming voltage Vset. Wherein the gain of the DAC 2120 is m, and the data signal data is binary number of eight bits, for example, the gain
The output of the dac 2120 further includes an integral nonlinear error voltage Vinl, which is an error value of a point where the error between the analog value and the real value is the largest at all the numerical points, that is, the output numerical value deviates from the linear maximum distance.
The op-amp cell 2210 includes a second operational amplifier U2, a first transistor M1, and a third resistor R3. A first input terminal of the second operational amplifier U2 is connected to the output terminal of the digital-to-analog converter 2120 for receiving the dimming voltage Vset, and an output terminal of the second operational amplifier U2 outputs the intermediate voltage Vin. The control terminal (gate) of the first transistor M1 is connected to the output terminal of the second operational amplifier U2 for receiving the intermediate voltage Vin, the first terminal (source) of the first transistor M1 is connected to the second input terminal of the second operational amplifier U2, and the second terminal (drain) of the first transistor M1) An intermediate current Iin is output. The first terminal of the third resistor R3 is connected to the first terminal of the first transistor M1, and the second terminal of the third resistor R3 is grounded. The second operational amplifier U2 and the first transistor M1 form a voltage follower, the first transistor M1 is, for example, an NMOS transistor, and the gate-source voltage Vgs of the first transistor M1 is turned on when it is greater than a predetermined voltage. The voltage provided to the third resistor R3 via the first terminal of the first transistor M1 is mx (Iref × R1+ Vos1) + Vin1+ Vos2, and Vos2 is the offset voltage of the second operational amplifier U2. The intermediate current at the second terminal of the first transistor M1 is equal to the current flowing through the third resistor R3. Intermediate current flow
The current mirror 2220 includes a second transistor M2 and a third transistor M3. The control terminal of the second transistor M2 is connected to the control terminal of the third transistor M3, the first terminal of the second transistor M2 is connected to the control terminal of the second transistor M2 and receives the intermediate current Iin, and the second terminal of the second transistor M2 receives the supply voltage. A first terminal of the third transistor M3 outputs the dimming current Idim, and a second terminal of the third transistor M3 receives the supply voltage. When the process parameters of the second transistor M2 and the second transistor M3 in the current mirror 2220 are equal, the ideal current ratio K of the current mirror 2220 is related to the width-to-length ratio of the second transistor M2 and the third transistor M3. In actual operation, the ideal current ratio K of the current mirror 2220 is also affected by the manufacturing process of the device in the current mirror and shifts, and the actual current ratio of the current mirror 2220 is K + Δ K, where Δ K is the current ratio shift value. Wherein the dimming current
The resistor R3 is, for example, a constant resistor.
The resistance of the first resistor R1 in the dimming circuit 2000 is adjustable, and the adjustment is performed based on the above parameters, so that the precision of the dimming current Idim can be improved, and the dimming current Idim is closer to or equal to the target dimming current.
In other embodiments, the digital-to-analog converter 2120 is removed from the dimming circuit 2000, and the dimming voltage is directly provided to the voltage conversion current module 2200 by the voltage adjusting unit 2110. The accuracy of the dimming current Idim can also be improved to be closer to or equal to the target dimming current.
Fig. 3 shows a further circuit schematic diagram of a dimming circuit for an LED provided according to an embodiment of the present disclosure. Referring to fig. 3, the dimming circuit 3000 includes a voltage generation module 3100 and a voltage conversion current module 3200. The voltage generation module 3100 includes a voltage adjustment unit 3110 and a digital-to-analog converter 2120. The voltage conversion current module 3200 includes an operational amplifier unit 3210 and a current mirror 2220. The digital-to-analog converter 2120 and the current mirror 2220 have the same circuit structure as that of the dimming circuit 2000, and are not described here again.
The voltage adjusting unit 3110 includes a current source I1 and a fourth resistor R4. Current source I1 provides a reference current Iref. The fourth resistor R4 is, for example, a constant resistor, and is connected between the current source I1 and ground. Further, the circuit also comprises a first operational amplifier U1, wherein a first input end is connected with a connection node of a current source I1 and a fourth resistor R4, and an output end is connected with a second input end and outputs a reference voltage Vref. The output end of the first operational amplifier U1 is connected to the second input end (inverting input end) to form a buffer, and the reference voltage Vref output by the output end of the first operational amplifier U1 is Iref × R4+ Vos 1. The buffer has infinite input impedance and small output impedance, and can improve the driving capability of the output reference voltage Vref.
The operational amplifier unit 3210 includes a second operational amplifier U2, a first transistor M1, and a second resistor R2. A first input terminal of the second operational amplifier U2 is connected to the output terminal of the digital-to-analog converter 2120 for receiving the dimming voltage Vset, and an output terminal of the second operational amplifier U2 outputs the intermediate voltage Vin. A control terminal (gate) of the first transistor M1 is connected to the output terminal of the second operational amplifier U2 to receive the intermediate voltage Vin, a first terminal (source) of the first transistor M1 is connected to the second input terminal of the second operational amplifier U2, and a second terminal (drain) of the first transistor M1 outputs the intermediate current Iin. The first end of the second resistor R2 is connected to the first end of the first transistor M1, and the second end of the second resistor R2 is grounded. The second resistor R2 is a variable resistor, the resistance of the second resistor R2 is equal to the target dimming current,The reference current Iref is related to the electrical parameters of other components (except the second resistor R2) in the voltage conversion current module 3200. The second operational amplifier U2 and the first transistor M1 form a voltage follower, the first transistor M1 is, for example, an NMOS transistor, and the gate-source voltage Vgs of the first transistor M1 is turned on when it is greater than a predetermined voltage. The voltage provided to the second resistor R2 via the first terminal of the first transistor M1 is mx (Iref × R4+ Vos1) + Vin1+ Vos2, and Vos2 is the offset voltage of the second operational amplifier U2. The intermediate current at the second terminal of the first transistor M1 is equal to the current flowing through the second resistor R2. Intermediate current flow
Further, the dimming current outputted in the present embodiment
The resistance of the second resistor R2 in the dimming circuit 3000 is adjustable, and the adjustment is performed based on the above parameters, so that the precision of the dimming current Idim can be improved, and the dimming current Idim is closer to or equal to the target dimming current.
In other embodiments, for example, a dimming circuit is also provided, and the third resistor R3 is replaced by a fifth resistor, for example, a variable resistor, based on the dimming circuit 2000. And then the precision of the dimming current Idim is improved by adjusting the resistance values of the first resistor R1 and the fifth resistor.
The LED dimming circuit provided by the disclosure can improve the precision of dimming current by adjusting the resistance parameter of the voltage adjusting unit and/or adjusting the resistance parameter of the voltage conversion current module. The dimming circuit provided by the disclosure can compensate the technical problem of dimming current precision reduction caused by a preparation process without changing a circuit structure.
The present disclosure also provides a backlight control system for driving and controlling a backlight assembly in a liquid crystal display device. The backlight control system comprises the LED dimming circuit, so that the precision of dimming current can be improved. Thereby realizing more stable and reliable backlight display effect of the backlight assembly. Further, the backlight control system drives the LED backlight assembly in a DC dimming mode, or a PWM dimming mode, or a combination thereof.
The present disclosure also provides a display device comprising the backlight control system provided above. The display device is, for example, a liquid crystal display device, including, for example, a mobile phone, a handheld computer, a wearable electronic device, and the like.
It should be noted that the numerical values in this document are only used for exemplary illustration, and in other embodiments of the present disclosure, other numerical values may be sampled to implement the present disclosure, and the present disclosure is not limited to this, which should be set reasonably according to actual situations.
Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present disclosure, and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention as herein taught are within the scope of the present disclosure.
It is also to be understood that the terms and expressions employed herein are used as terms of description and not of limitation, and that the embodiment or embodiments of the specification are not limited to those terms and expressions. The use of such terms and expressions is not intended to exclude any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications may be made within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims should be looked to in order to cover all such equivalents.
Claims (12)
1. A dimming circuit for an LED, comprising:
a voltage generation module providing a dimming voltage; and
a voltage conversion current module connected with the voltage adjustment module for converting the dimming voltage into dimming current and outputting the dimming current,
wherein a resistance parameter in the voltage generation module and/or the voltage conversion current module is adjusted to improve the precision of the dimming current.
2. The LED dimming circuit of claim 1, wherein the voltage generation module adjusts a resistance parameter to adjust the dimming voltage, and the precision of the dimming current converted based on the adjusted dimming voltage is improved.
3. The LED dimming circuit of claim 2, wherein the voltage generation module further adjusts the dimming voltage according to a digital signal.
4. The LED dimming circuit of claim 1, wherein the voltage-to-current conversion module adjusts a resistance parameter to compensate a conversion coefficient thereof, and the dimming current obtained based on the compensated conversion coefficient has an improved precision, and the conversion coefficient is related to an electrical parameter of a component in the voltage-to-current conversion module.
5. The LED dimming circuit of claim 3, wherein the voltage generation module comprises:
the voltage adjusting unit adjusts the self-resistance parameter to provide adjustable reference voltage; and
and the digital-to-analog converter is connected with the voltage adjusting unit and outputs the dimming voltage based on the reference voltage and the digital signal.
6. The LED dimming circuit of claim 5, wherein the voltage adjustment unit comprises:
a current source providing a reference current; and
and the first resistor is connected with the current source in series, and the resistance value of the first resistor is related to the target dimming current, the reference current and the conversion coefficient of the voltage conversion current module.
7. The LED dimming circuit of claim 5, wherein the digital signal is editable.
8. The LED dimming circuit of claim 6, wherein the voltage adjustment unit further comprises:
and the first input end of the first operational amplifier is connected with the connection node of the current source and the first resistor, the second input end of the first operational amplifier is connected with the output end of the first operational amplifier, and the output end of the first operational amplifier outputs the reference voltage.
9. The LED dimming circuit of claim 4, wherein the voltage conversion current module comprises:
the operational amplifier unit is connected with the voltage adjusting module, compensates a conversion coefficient by adjusting self resistance parameters, and generates an intermediate current based on the dimming voltage; and
and the current mirror is connected with the operational amplifier unit and provides the dimming current proportional to the intermediate current.
10. The LED dimming circuit of claim 9, wherein the operational amplifier unit comprises:
the first input end of the second operational amplifier receives the dimming voltage, and the output end of the second operational amplifier outputs an intermediate voltage;
a first transistor, a control terminal of which receives the intermediate voltage, a first terminal of which is connected to a second input terminal of the second operational amplifier, and a second terminal of which outputs the intermediate current;
a second resistor having a first terminal connected to the first terminal of the first transistor and a second terminal connected to ground,
the resistance value of the second resistor is adjustable, and is related to the target dimming current, the reference current and electrical parameters of other components in the voltage conversion current module.
11. A backlight control system, comprising: dimming circuit of an LED according to any of claims 1-10.
12. A display device, comprising: the backlight control system of claim 11.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210111729.0A CN114495844A (en) | 2022-01-26 | 2022-01-26 | Dimming circuit, backlight control system and display device of LED |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210111729.0A CN114495844A (en) | 2022-01-26 | 2022-01-26 | Dimming circuit, backlight control system and display device of LED |
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| JP2010003115A (en) * | 2008-06-20 | 2010-01-07 | Mitsumi Electric Co Ltd | Constant current circuit |
| CN102958236A (en) * | 2011-08-31 | 2013-03-06 | 美国亚德诺半导体公司 | Current control circuit and light emitting diode driver as well as manufacturing method thereof |
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Address after: Room 101, floor 1, building 3, yard 18, Kechuang 10th Street, Beijing Economic and Technological Development Zone, Daxing District, Beijing 100176 Applicant after: Beijing yisiwei Computing Technology Co.,Ltd. Address before: Room 101, floor 1, building 3, yard 18, Kechuang 10th Street, Beijing Economic and Technological Development Zone, Daxing District, Beijing 100176 Applicant before: Beijing yisiwei Computing Technology Co.,Ltd. |
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| CB02 | Change of applicant information |