CN212907022U - Control panel for controlling backlight brightness of liquid crystal display - Google Patents
Control panel for controlling backlight brightness of liquid crystal display Download PDFInfo
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- CN212907022U CN212907022U CN202021697054.5U CN202021697054U CN212907022U CN 212907022 U CN212907022 U CN 212907022U CN 202021697054 U CN202021697054 U CN 202021697054U CN 212907022 U CN212907022 U CN 212907022U
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- liquid crystal
- operational amplifier
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- control panel
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Abstract
The utility model discloses a control panel for controlling liquid crystal screen luminance in a poor light relates to display control field, and this control panel includes DC-DC converter and switching element, logic treater, comparison driver, feedback comparator and current sampling component, the DC-DC converter is connected with the LCD screen, outside PWM, EN signal and the output of feedback comparator is connected with logic treater's input, logic treater's output and comparison driver's input are connected, comparison driver's output and switching element are connected for control switch element's break-make, and then control the luminance of LCD screen, switching element is connected with LCD screen and current sampling component, current sampling component's output and feedback comparator's input are connected. The utility model discloses control accuracy is higher, and relatively safe.
Description
Technical Field
The utility model relates to a display control field, concretely relates to a control panel for controlling liquid crystal display luminance in a poor light.
Background
At present, the backlight control of most liquid crystal screens mainly comprises a current drive mode and a voltage drive mode, namely, the input end of PWM (Pulse width modulation) of the liquid crystal screen is directly connected to a drive chip, the drive chip is used for adjusting output voltage or current, and further adjusting the brightness of the display screen.
SUMMERY OF THE UTILITY MODEL
To the defect that exists among the prior art, the utility model aims to provide a control panel for controlling liquid crystal display luminance in a poor light, control accuracy is higher, and relatively safe.
In order to achieve the above purpose, the utility model adopts the technical proposal that:
the control panel for controlling the backlight brightness of the liquid crystal screen comprises a DC-DC converter and a switch element, and further comprises a logic processor, a comparison driver, a feedback comparator and a current sampling element, wherein the DC-DC converter is connected with the liquid crystal screen, the output end of the feedback comparator is connected with the input end of the logic processor, the output end of the logic processor is connected with the input end of the comparison driver, the output end of the comparison driver is connected with the switch element and used for controlling the on-off of the switch element so as to control the brightness of the liquid crystal screen, the switch element is connected with the liquid crystal screen and the current sampling element, and the output end of the current sampling element is connected with the input end of the feedback comparator.
Further, the switching element is a field effect transistor with the model number of 2908.
Further, the current sampling element comprises four first resistors R1 connected in parallel with each other.
Further, the comparison driver comprises a first operational amplifier, wherein a positive input end of the first operational amplifier is connected with an output end of the logic processor, a negative input end of the first operational amplifier is connected with an external power supply, and an output end of the first operational amplifier is connected with an input end of the switching element.
Furthermore, a first voltage-dividing resistor R2 and a second voltage-dividing resistor R3 which are connected in parallel with each other are arranged between the negative input end of the first operational amplifier and an external power supply, and a first capacitor C1 is connected in series with the second voltage-dividing resistor R3.
Further, a power supply end of the first operational amplifier is connected to an external power supply, a ground end of the first operational amplifier is grounded, a fourth resistor R4 is connected in series between an output end of the first operational amplifier and the switching element, and a fifth resistor R5 is connected in parallel between the output end of the first operational amplifier and the power supply end.
Furthermore, the feedback comparator comprises a second operational amplifier, a negative electrode input end of the second operational amplifier is connected with the current sampling element, a positive electrode input end of the second operational amplifier is connected with an external voltage, and an output end of the second operational amplifier is connected with an input end of the logic processor.
Further, a third voltage dividing resistor R5 and a fourth voltage dividing resistor R6 are connected in parallel between the positive input end of the two operational amplifiers and the external voltage, and a second capacitor C2 is connected in series with the fourth voltage dividing resistor R6.
Compared with the prior art, the utility model has the advantages of:
(1) the utility model discloses a control panel for controlling LCD screen backlight brightness, including DC-DC converter and switching element, logic processor, comparison driver, feedback comparator and current sampling component, DC-DC converter is connected with the LCD screen, the output of outside PWM, EN signal and feedback comparator is connected with logic processor's input, logic processor's output is connected with comparison driver's input, comparison driver's output is connected with switching element for the break-make of control switching element, and then control LCD screen's brightness, switching element is connected with LCD screen and current sampling component, current sampling component's output is connected with feedback comparator's input, outside control signal EN, PWM and feedback comparator's output is behind logic processor, control comparison driver, and then control switching element's break-make, therefore, the backlight brightness of the liquid crystal screen is controlled, the control precision is high, meanwhile, the current sampling element inputs the current of the liquid crystal screen into the logic processor through the feedback comparator, the on-off of the switch element can be adjusted in real time, and the safety is high.
Drawings
Fig. 1 is a schematic structural diagram of a control panel for controlling backlight brightness of a liquid crystal display according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a comparison driver, switching element;
fig. 3 is a circuit diagram of a feedback comparator and a current sampling element.
In the figure: the circuit comprises a 1-DC-DC converter, a 2-switching element, a 3-logic processor, a 4-comparison driver, a 5-feedback comparator, a 6-current sampling element, a 7-liquid crystal screen, an 8-first operational amplifier and a 9-second operational amplifier.
Detailed Description
The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
Referring to fig. 1, an embodiment of the present invention provides a control panel for controlling backlight brightness of a liquid crystal display, including a DC-DC converter 1 (a Direct current-Direct current converter, a voltage converter for converting an input voltage and then effectively outputting a fixed voltage) and a switch element 2, a logic processor 3, a comparison driver 4, a feedback comparator 5 and a current sampling element 6, where the DC-DC converter 1 is connected to the liquid crystal display 7, an output terminal of an external PWM, EN signal and feedback comparator 5 is connected to an input terminal of the logic processor 3, an output terminal of the logic processor 3 is connected to an input terminal of the comparison driver 4, an output terminal of the comparison driver 4 is connected to the switch element 2 for controlling on/off of the switch element 2, and further controlling brightness of the liquid crystal display 7, the switch element 2 is connected to the liquid crystal display 7 and the current sampling element 6, the output of the current sampling element 6 is connected to the input of the feedback comparator 5.
Referring to fig. 2 and 3, in the present embodiment, the switching element 2 is a field effect transistor of type 2908, an S pole of the field effect transistor is connected to a cathode of the light emitting tube of the liquid crystal panel, a G pole of the field effect transistor is connected to an output of the comparison driver 4, and a D pole of the field effect transistor is connected to the current sampling element 6.
The current sampling element 6 comprises four first resistors R1 connected in parallel, one end of each first resistor R1 is connected with the D pole of the switch element 2, the other end of each first resistor R1 is grounded, the resistance values of the first resistors R1 are all 0.27 ohm, the current of the liquid crystal screen 7 at the maximum brightness is 1.2A, after passing through the current sampling element 6, the voltage is 0.1V, the current is connected to the negative end of the feedback comparator 5, according to the characteristics of the liquid crystal screen, the maximum receiving current of the feedback comparator 5 is 1.8A, the corresponding feedback voltage is 0.14V, and therefore the input voltage of the positive end of the feedback comparator 5 is determined to be 0.14V.
The comparison driver 4 comprises a first operational amplifier 8, a positive input end of the first operational amplifier 8 is connected with an output end of the logic processor 3, a negative input end of the first operational amplifier 8 is connected with an external power supply (5V), an output end of the first operational amplifier is connected with an input end of the switching element 2, a first voltage-dividing resistor R2 and a second voltage-dividing resistor R3 which are mutually connected in parallel are arranged between the negative input end of the first operational amplifier 8 and the external power supply, and a first capacitor C1 is connected to the second voltage-dividing resistor R3 in series.
A power supply terminal of the first operational amplifier 8 is connected to an external power supply, a ground terminal is grounded, a fourth resistor R4 is connected in series between the output terminal of the first operational amplifier 8 and the switching element 2, and a fifth resistor R5 is connected in parallel between the output terminal of the first operational amplifier 8 and the power supply terminal.
The feedback comparator 5 comprises a second operational amplifier 9, a negative input end of the second operational amplifier 9 is connected with the current sampling element 6, a positive input end is connected with an external voltage, an output end is connected with an input end of the logic processor 3, a third voltage dividing resistor R5 and a fourth voltage dividing resistor R6 are connected between the positive input end of the second operational amplifier 9 and the external voltage in parallel, a second capacitor C2 is connected to the fourth voltage dividing resistor R6 in series, and the resistance values of the third voltage dividing resistor R5 and the fourth voltage dividing resistor R6 are 10K and 270 ohms.
The utility model discloses an output of external control signal EN, PWM and feedback comparator 5 is behind logic processor 3, control comparison driver 4, and then control switch element 2's break-make to control LCD screen 7's luminance in a poor light.
The present invention is not limited to the above preferred embodiments, and any person can obtain other products in various forms without departing from the scope of the present invention, but any change in shape or structure is within the scope of protection.
Claims (8)
1. A control board for controlling the backlight brightness of a liquid crystal panel, comprising a DC-DC converter (1) and a switching element (2), characterized in that: the LED display panel is characterized by further comprising a logic processor (3), a comparison driver (4), a feedback comparator (5) and a current sampling element (6), wherein the DC-DC converter (1) is connected with the liquid crystal screen (7), the output end of the feedback comparator (5) is connected with the input end of the logic processor (3), the output end of the logic processor (3) is connected with the input end of the comparison driver (4), the output end of the comparison driver (4) is connected with the switch element (2) and used for controlling the on-off of the switch element (2) and further controlling the brightness of the liquid crystal screen (7), the switch element (2) is connected with the liquid crystal screen (7) and the current sampling element (6), and the output end of the current sampling element (6) is connected with the input end of the feedback comparator (5).
2. The control panel for controlling the backlight brightness of the liquid crystal panel as claimed in claim 1, wherein: the switch element (2) is a field effect transistor with the model number of 2908.
3. The control panel for controlling the backlight brightness of the liquid crystal panel according to claim 2, wherein: the current sampling element (6) comprises four first resistors R1 connected in parallel with each other.
4. A control panel for controlling the backlight brightness of a liquid crystal panel as claimed in claim 3, wherein: the comparison driver (4) comprises a first operational amplifier (8), wherein the positive pole input end of the first operational amplifier (8) is connected with the output end of the logic processor (3), the negative pole input end of the first operational amplifier is connected with an external power supply, and the output end of the first operational amplifier is connected with the input end of the switch element (2).
5. The control panel for controlling the backlight brightness of the liquid crystal display panel according to claim 4, wherein: a first voltage-dividing resistor R2 and a second voltage-dividing resistor R3 which are mutually connected in parallel are arranged between the negative electrode input end of the first operational amplifier (8) and an external power supply, and a first capacitor C1 is connected to the second voltage-dividing resistor R3 in series.
6. The control panel for controlling the backlight brightness of the liquid crystal display panel according to claim 5, wherein: the power supply end of the first operational amplifier (8) is connected with an external power supply, the grounding end of the first operational amplifier is grounded, a fourth resistor R4 is connected in series between the output end of the first operational amplifier (8) and the switching element (2), and a fifth resistor R5 is connected in parallel between the output end of the first operational amplifier (8) and the power supply end.
7. The control panel for controlling the backlight brightness of the liquid crystal panel according to claim 6, wherein: the feedback comparator (5) comprises a second operational amplifier (9), the negative electrode input end of the second operational amplifier (9) is connected with the current sampling element (6), the positive electrode input end of the second operational amplifier is connected with external voltage, and the output end of the second operational amplifier is connected with the input end of the logic processor (3).
8. The control panel for controlling the backlight brightness of the liquid crystal panel according to claim 7, wherein: a third voltage dividing resistor R5 and a fourth voltage dividing resistor R6 are connected in parallel between the positive input end of the two operational amplifiers (9) and the external voltage, and a second capacitor C2 is connected in series with the fourth voltage dividing resistor R6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021697054.5U CN212907022U (en) | 2020-08-14 | 2020-08-14 | Control panel for controlling backlight brightness of liquid crystal display |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021697054.5U CN212907022U (en) | 2020-08-14 | 2020-08-14 | Control panel for controlling backlight brightness of liquid crystal display |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212907022U true CN212907022U (en) | 2021-04-06 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021697054.5U Active CN212907022U (en) | 2020-08-14 | 2020-08-14 | Control panel for controlling backlight brightness of liquid crystal display |
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| Country | Link |
|---|---|
| CN (1) | CN212907022U (en) |
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2020
- 2020-08-14 CN CN202021697054.5U patent/CN212907022U/en active Active
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