CN109036293A - A kind of liquid crystal display brightness regulating circuit and a kind of liquid crystal display - Google Patents
A kind of liquid crystal display brightness regulating circuit and a kind of liquid crystal display Download PDFInfo
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- CN109036293A CN109036293A CN201810842707.5A CN201810842707A CN109036293A CN 109036293 A CN109036293 A CN 109036293A CN 201810842707 A CN201810842707 A CN 201810842707A CN 109036293 A CN109036293 A CN 109036293A
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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
- G09G3/3413—Details of control of colour illumination sources
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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
- G09G3/36—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
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/06—Adjustment of display parameters
- G09G2320/0626—Adjustment of display parameters for control of overall brightness
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- 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)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
The invention discloses a kind of liquid crystal display brightness regulating circuit and liquid crystal displays.The liquid crystal display brightness regulating circuit includes: backlight, switch chip and variable resistance circuit；Switch chip is connected between working power and the anode of backlight, and switch chip extinguishes backlight when liquid crystal is overturn to eliminate liquid crystal display smear；The cathode of backlight is grounded through variable resistance circuit, and the feedback end that an end of variable resistance circuit connection backlight is connected to switch chip changes the operating current size of switch chip output, adjust the brightness of liquid crystal display by changing the resistance value of variable resistance circuit.The application extinguishes backlight when liquid crystal is overturn by switch chip to eliminate the smear of liquid crystal display, it is simultaneously to overcome the problems, such as that black plug causes liquid crystal display brightness lower, increase the variable resistance circuit for being connected to switch chip feedback end, by the resistance value for adjusting variable resistance circuit, the operating current size for changing switch chip, to adjust the brightness of liquid crystal display.
Description
Technical field
The present invention relates to technical field of liquid crystal display, in particular to a kind of liquid crystal display brightness regulating circuit and a kind of liquid crystal
Screen.
Background technique
In the application such as virtual reality device, requirement of the people to Showing Effectiveness On Screen is higher and higher.Some equipment can be selected
Select using AMOLED that (Active-matrix organic light emitting diode, Chinese name: active matrix is organic
Light-emitting diode) screen, to meet the needs of to screen quick response fast refresh, but AMOLED screen is at high cost, therefore
Some equipment substitute OLED screen curtain using the LCD screen of quick response.But since the liquid crystal of liquid crystal display inherently is rung
It answers speed slow, causes to have strong smear problem when viewing.In order to solve the smear problem of liquid crystal display, common method
It is the addition black plug circuit on the backlight circuit of liquid crystal, it may be assumed that light screen certain time (1ms in the ending of every frame signal
Left and right), and remaining time of every frame signal extinguishes screen, can avoid human eye by the side for the screen that goes out when smear in this way
The problem of feeling smear.
However, the mode of above-mentioned black plug can reduce the brightness of liquid crystal display, the perception of user is influenced.And existing
It is by, directly to inside screen write current value, carrying out control flow by register etc. in AMOLED screen brightness regulation scheme
Curtain brightness, it is not particularly suited for the brightness regulation of liquid crystal display.Accordingly, it is desirable to provide the scheme of adjusting brightness a kind of new controls
The brightness of liquid crystal display.
Summary of the invention
The problem of adjusting is needed in view of prior art liquid crystal display brightness, proposes a kind of liquid crystal display brightness regulation of the invention
Circuit and a kind of liquid crystal display, to overcome the above problem or at least to be partially solved the above problem.
To achieve the goals above, present invention employs following technical solutions:
According to one aspect of the present invention, a kind of liquid crystal display brightness regulating circuit is provided, comprising: backlight, switch core
Piece and variable resistance circuit；Switch chip is connected between working power and the anode of backlight, and switch chip is overturn in liquid crystal
When, extinguish backlight to eliminate liquid crystal display smear；The cathode of backlight is grounded through variable resistance circuit, variable resistance circuit
One end of connection backlight is connected to the feedback end of switch chip, by changing the resistance value of variable resistance circuit, changes switch core
The size of current of piece output, adjusts the brightness of liquid crystal display.
Optionally, variable resistance circuit includes: a plurality of adjusting branch being arranged in parallel between the cathode and ground of backlight,
Every adjusting branch includes adjusting resistance, and at least one adjusting branch further includes having and adjusting the concatenated switch of resistance
Pipe, the intednsity circuit of the control terminal connection liquid crystal display of switching tube.
Optionally, switching tube is metal-oxide-semiconductor, and the different universal inputs that the grid of each metal-oxide-semiconductor is connected to intednsity circuit are defeated
Outgoing interface.
Optionally, liquid crystal display brightness regulating circuit further include: DC voltage booster circuit, filter capacitor and controlling circuit of voltage regulation；
The input terminal of the output end connection switch chip of DC voltage booster circuit；
Filter capacitor is connected between the output end of DC voltage booster circuit and ground；
Controlling circuit of voltage regulation is connected to DC voltage booster circuit, and in the power up phase of liquid crystal display brightness regulating circuit, control is straight
Supply voltage is discontinuously increased the operating voltage for backlight by stream booster circuit.
Optionally, filter capacitor is electrolytic capacitor.
Optionally, controlling circuit of voltage regulation includes: the switch control electricity being connected between supply voltage and DC voltage booster circuit
Road；ON-OFF control circuit acquires the voltage value of supply voltage, when the voltage value of supply voltage is lower than the first predeterminated voltage, disconnects
The connection of supply voltage and DC voltage booster circuit restores power supply electricity when the voltage value of supply voltage is higher than the second predeterminated voltage
The connection of pressure and DC voltage booster circuit.
Optionally, ON-OFF control circuit includes pressure sampling circuit, comparator, switching regulator controller and switching tube, switch
Pipe is connected between supply voltage and DC voltage booster circuit；
The input terminal of the output end connection comparator of pressure sampling circuit；
The output end connection switch tube controller of comparator；
Switching regulator controller is disconnected or is connected according to the comparison result control switch pipe of comparator.
Optionally, controlling circuit of voltage regulation includes: signal output apparatus, and the output end of signal output apparatus is connected to direct current liter
The enable end of volt circuit, in the power up phase of liquid crystal display brightness regulating circuit, signal output apparatus passes through output pulse width tune
Signal processed, control DC voltage booster circuit interruption boosting.
Optionally, after the completion of liquid crystal display brightness regulating circuit powers on, signal output apparatus exports stable voltage control
Signal controls DC voltage booster circuit continuous work.
According to another aspect of the invention, a kind of liquid crystal display is provided, liquid crystal display is provided with liquid crystal any one of as above
Shield brightness regulating circuit.
In conclusion the beneficial effects of the present invention are:
By utilizing switch chip, when liquid crystal overturning, extinguishes backlight to eliminate the smear of liquid crystal display, be simultaneously
Overcome the problems, such as that black plug causes liquid crystal display brightness lower and unadjustable, increase be connected to switch chip feedback end can power transformation
Resistance circuit, by adjusting the resistance value of variable resistance circuit, change switch chip is supplied to the operating current size of backlight, thus
Adjust the brightness of liquid crystal display.
Detailed description of the invention
Fig. 1 is the composed structure schematic diagram of liquid crystal display brightness regulating circuit provided by one embodiment of the present invention；
Fig. 2 is the connection schematic diagram for the liquid crystal display brightness regulating circuit that the present invention another embodiment provides；
Fig. 3 is the circuit connection diagram for increasing ON-OFF control circuit in the embodiment depicted in figure 2；
Fig. 4 is the schematic diagram of the unlike signal control DC voltage booster circuit power up used；
Fig. 5 is to power on voltage waveform view when controlling DC voltage booster circuit using common high level switching signal；
Fig. 6 is to power on voltage waveform view when controlling DC voltage booster circuit using pwm signal.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with attached drawing to embodiment party of the present invention
Formula is described in further detail.
Technical concept of the invention is: by utilizing switch chip, when liquid crystal overturning, extinguishing backlight to eliminate
The smear of liquid crystal display, while to overcome the problems, such as that black plug causes liquid crystal display brightness lower and unadjustable, it increases and is connected to out
The variable resistance circuit for closing chip feedback end changes switch chip and is supplied to backlight by adjusting the resistance value of variable resistance circuit
The operating current size of lamp, to adjust the brightness of liquid crystal display.
Fig. 1 outputs the composed structure schematic diagram of this emperorship liquid crystal display brightness regulating circuit one embodiment, such as Fig. 1 institute
Show, a kind of liquid crystal display brightness regulating circuit, comprising: LED backlight, switch chip and variable resistance circuit.Switch chip connection
Between working power and the anode of backlight, switch chip extinguishes backlight when liquid crystal is overturn to eliminate liquid crystal display
Smear；The cathode of backlight is grounded through variable resistance circuit, and an end of variable resistance circuit connection backlight is connected to switch chip
Feedback end, pass through change variable resistance circuit resistance value, change switch chip output operating current size, adjust liquid crystal
The brightness of screen.
Fig. 2 shows a physical circuit connection structures of the application liquid crystal display brightness regulating circuit.As shown in Fig. 2, can
Power transformation resistance circuit includes: a plurality of adjusting branch being arranged in parallel between the cathode and ground of backlight, and every adjusting branch wraps
It has included adjusting resistance (R4, R5, R6, R3), and at least one adjusting branch further includes having and adjusting the concatenated switching tube of resistance, figure
In 2, corresponding resistance R4, R5 and R6 of adjusting is respectively arranged with switching tube Q1, Q2 and Q3, and the control terminal of switching tube Q1, Q2 and Q3 connect
Connect the intednsity circuit of liquid crystal display.Resistance R3 is adjusted to connect always in circuit.
Specifically, switching tube Q1, Q2 and Q3 is metal-oxide-semiconductor, is managed shown in Fig. 2 for N-MOS, and the grid of each metal-oxide-semiconductor is connected to
The different universal input/output interfaces of intednsity circuit, i.e. GPIO1, GPIO2 and GPIO3.
To which circuit shown in Fig. 2 constitutes three-level light adjusting circuit, and every level-one is by N-MOS pipe one resistance of series connection
Composition accesses a GPIO in the grid grade (G) of metal-oxide-semiconductor and controls signal, and when GPIO is High, metal-oxide-semiconductor is opened, at this time switch core
The resistance that piece FB point is directly connect with the source level of metal-oxide-semiconductor (S) is connected；When GPIO is Low, metal-oxide-semiconductor is closed, at this time metal-oxide-semiconductor
It is equivalent to open-circuit condition, source level institute connecting resistance is invalid.By adjusting the resistance value of R4, R5 and R6, and with GPIO1, GPIO2 and
GPIO3 controls R4, R5 and R6 and forms the in parallel of various combination with R3, can form multiple combinations scheme, thus by changing over the ground
The resistance value of resistance realizes the feedback to switch chip FB pin, to adjust the electric current of backlight LED light, to realize brightness adjustment.
For the circuit shown in Fig. 2, the end FB voltage is 0.177V, R4=R5=R6=6 Ω, R3=10 Ω, corresponding
Tri- kinds of height combinations of states of GPIO1/GPIO2/GPIO3 are shown in following table:
| GPIO1 | GPIO2 | GPIO3 | LED current |
| 0 | 0 | 0 | 88.5mA |
| 0 | 0 | 1 | 118mA |
| 0 | 1 | 1 | 147.5mA |
| 1 | 1 | 1 | 177mA |
The resistance value of resistance R4, R5 and R6 can be set as needed, and as R4 ≠ R5 ≠ R6, be combined using the high and low energy of GPIO
A variety of resistor proposals out.In addition, the number for controlling to adjust branch by increasing GPIO can also realize the electric current adjustment side of more stages
Case realizes finer brightness regulation.
In some embodiments of the present application, the circuit with reference to shown in Fig. 2, liquid crystal display brightness regulating circuit further include: direct current
Booster circuit and filter capacitor C1 and controlling circuit of voltage regulation.
The input terminal of the output end connection switch chip of DC voltage booster circuit, for increasing supply voltage for backlight
Operating voltage is supplied to switch chip use, is unsatisfactory for backlight light working voltage (example to solve supply voltage lower (such as 5V)
Such as 30V) demand.
Filter capacitor C1 is connected between the output end of DC voltage booster circuit and ground, is made by the energy storage of filter capacitor C1
With, supplemental current is provided when switch chip closure, to make up the problem of DC voltage booster circuit response speed deficiency, thus
Reduce the ripple generated due to switch chip fast opening and closing, reduces the adverse effect to supply voltage.Preferably, the filtered electrical
Appearance C1 is electrolytic capacitor, has biggish capacitance, to be the LED backlight of high current high brightness in switch chip closure
Lamp provides enough electric currents, such as in Fig. 2, and filter capacitor C1 is the alminium electrolytic condenser of 470uF/50V.
Refering to what is shown in Fig. 2, filter capacitor C1 is arranged by the output end in DC voltage booster circuit, it can be by filter capacitor
The energy storage of C1 acts on, and provides supplemental current when switch chip closure, it is insufficient to make up DC voltage booster circuit response speed
Problem, to reduce switch chip in PWM (Pulse WidthModulation, Chinese: pulse width modulation) light modulation letter
The ripple for number controlling lower fast opening and closing and generating, reduces the de-stabilising effect to supply voltage.
In addition, it is contemplated that the filter capacitor C1 of access needs to charge in power up phase, supply voltage can be dragged down, and filter
The capacitance of capacitor C1 drags down more greatly effect and is more obvious, and may result in that supply voltage is too low or even trigger circuit protection, causes
Circuit can not normally work on power.Therefore, controlling circuit of voltage regulation is additionally provided with (i.e. in the application circuit embodiments shown in Fig. 3
ON-OFF control circuit in Fig. 3), controlling circuit of voltage regulation is connected to DC voltage booster circuit, in the upper of liquid crystal display brightness regulating circuit
In the electric stage, supply voltage is discontinuously increased the operating voltage for backlight by control DC voltage booster circuit, to avoid the filter of access
Wave capacitor C1 quick charge causes power up supply voltage excessively to be dragged down, and stablizes the supply voltage of power up phase.
Referring to Fig. 3 physical circuit, controlling circuit of voltage regulation is the switch being connected between supply voltage and DC voltage booster circuit
Control circuit；ON-OFF control circuit acquires the voltage value of supply voltage, when the voltage value of supply voltage is lower than the first predeterminated voltage
When, the connection of supply voltage and DC voltage booster circuit is disconnected, when the voltage value of supply voltage is higher than the second predeterminated voltage, is restored
The connection of supply voltage and DC voltage booster circuit.
Specifically, in Fig. 3, ON-OFF control circuit include sequentially connected pressure sampling circuit (including divider resistance R7 and
R8), comparator U1, switching regulator controller U2 and switching tube Q4, switching tube Q4 are connected on supply voltage VBUS and DC boosting electricity
Between road.
The voltage value of pressure sampling circuit partial pressure acquisition supply voltage VBUS, the output end of pressure sampling circuit divide
Resistance R7 connects an input terminal of comparator U1 with the connecting pin of R8.
Comparator U1 by the collected voltage value of pressure sampling circuit compared with the first predeterminated voltage and the second predeterminated voltage,
The output end connection switch tube controller U2 of comparator U1.
Switching regulator controller U2 is disconnected or is connected according to the comparison result control switch pipe Q4 of comparator U1, to disconnect or connect
Logical supply voltage and DC voltage booster circuit.
The working principle of circuit shown in Fig. 3 are as follows:
By adjusting the resistance value of R7 and R8, can achieve when voltage of VBUS is lower than the first predeterminated voltage, comparator U1 is defeated
Out to be low, disconnected to control Q4 (N-MOS pipe), after disconnection, the DC boosting chip that VBUS electric current can not be supplied to rear end makes
With boosting stops, and fluctuates reduce on VBUS at this time, and voltage of VBUS value increases, and when being increased to the second predeterminated voltage, passes through partial pressure
The partial pressure value that resistance R7 and R8 enter comparator U1 is higher than the second predeterminated voltage, and comparator U1 exports high level, to control Q4
It opens, drain electrode (D) and source level (S) are connected, and VBUS continues to power to back-end circuit.By the switch and closure of Q4, between realizing
It powers disconnectedly to back end DC booster circuit, to extend the pressure rising time of DC voltage booster circuit, ensure that voltage of VBUS begins
Eventually on a safe voltage value, the normal work in power up phase of VBUS ensure that.
In circuit shown in Fig. 3, the first predeterminated voltage is lower than the second predeterminated voltage, and setting comparator U1 compares for hysteresis
Device, so that the process of comparison voltage be avoided to shake.
In another embodiment of the application, controlling circuit of voltage regulation includes: signal output apparatus, signal output apparatus it is defeated
Outlet is connected to the enable end of DC voltage booster circuit, for example, the enable end EN of DC boosting chip shown in Fig. 2.In circuit
Power up phase, signal output apparatus control DC voltage booster circuit interruption boosting by output pulse width modulated signal.
On the basis of the above, after the completion of the anti-smear circuit of liquid crystal display powers on, signal output apparatus continues to output stable
Voltage control signal controls DC voltage booster circuit continuous work.
With reference to Fig. 4, the unlike signal to use controls the schematic diagram of DC voltage booster circuit power up.
As shown in figure 4, the enable end EN of the common chip of DC boosting in the prior art, by being changed to from low level Off
High level On makes chip be enabled and starts to work normally, in output end vo ut output system required voltage.But work as output end
When being connected to very big capacitor, for example, 470uF alminium electrolytic condenser C1 used in Fig. 2, since the voltage at capacitor both ends cannot be mutated, meeting
Cause immediate current very big, such as 2-3A even higher, it is big to will lead to mains voltage ripple in this way, causes system normal
Work, the voltage waveform that powers at this time can be with refering to what is shown in Fig. 5, know that supply voltage is obviously dragged down in power up phase, can shadow
It rings and arrives normal power supply, in some instances it may even be possible to which triggering power protection causes power supply to stop.
Further, since transient current is excessive, when supply voltage is provided by the USB port of PC or notebook,
The USB of PC or notebook will appear surge of electric power, cause USB can not normal use, if supply voltage be battery provide
Words will lead to battery automatic protection since immediate current is excessive, stop power supply.These can all jeopardize connection and use the liquid crystal
The electronic equipment of screen.
It is as above in order to solve the problems, such as, as shown in Figure 4 and Figure 6, in the present embodiment, by signal output apparatus, by direct current
The enable end EN signal of booster circuit becomes: power up phase EN signal uses PWM control mode, when filter capacitor charging in rear end is full
After, pwm signal is changed to high level signal.To, the interruption disconnection with ON-OFF control circuit shown in Fig. 3 has similar effects,
The boost process of DC voltage booster circuit is discontinuously realized, so as to avoid excessive charging current is generated, avoids power supply electricity
Pressure is excessively dragged down, at this time power on voltage waveform as shown in fig. 6, it is found that power up supply voltage is not obviously dragged down,
It is more stable.
On the basis of above-described embodiment of the application, signal output apparatus is by adjusting the pulse width modulation letter exported
Number frequency and/or duty ratio, the boost process of DC voltage booster circuit is adjusted, according to the size of the needs of system and capacitor
It is adjusted.Above-mentioned signal output apparatus is for example using microcontroller implementation.
In addition, the liquid crystal display is provided with liquid crystal display brightness tune any one of as above disclosed herein as well is a kind of liquid crystal display
Economize on electricity road.
The above, the only specific embodiment of the application, under the above-mentioned introduction of the application, those skilled in the art
Other improvement or deformation can be carried out on the basis of the above embodiments.It will be understood by those skilled in the art that above-mentioned tool
The purpose of the application is only preferably explained in body description, and the protection scope of the application should be subject to the protection scope in claims.
Claims (10)
1. a kind of liquid crystal display brightness regulating circuit characterized by comprising backlight, switch chip and variable resistance circuit；Institute
Switch chip is stated to be connected between working power and the anode of the backlight, the switch chip liquid crystal overturn when,
Extinguish the backlight to eliminate liquid crystal display smear；The cathode of the backlight is grounded through the variable resistance circuit, it is described can
The end that power transformation resistance circuit connects the backlight is connected to the feedback end of the switch chip, by changing the variable resistance electricity
The resistance value on road changes the operating current size of the switch chip output, adjusts the brightness of liquid crystal display.
2. liquid crystal display brightness regulating circuit according to claim 1, which is characterized in that
The variable resistance circuit includes: a plurality of adjusting branch being arranged in parallel between the cathode and ground of the backlight, often
It includes adjusting resistance that item, which adjusts branch, and at least one adjusting branch further includes having and adjusting the concatenated switching tube of resistance,
The intednsity circuit of the control terminal connection liquid crystal display of the switching tube.
3. liquid crystal display brightness regulating circuit according to claim 2, which is characterized in that
The switching tube is metal-oxide-semiconductor, and the different universal inputs that the grid of each metal-oxide-semiconductor is connected to the intednsity circuit are defeated
Outgoing interface.
4. liquid crystal display brightness regulating circuit according to claim 1-3, which is characterized in that
The liquid crystal display brightness regulating circuit further include: DC voltage booster circuit, filter capacitor and controlling circuit of voltage regulation；
The output end of the DC voltage booster circuit connects the input terminal of the switch chip；
The filter capacitor is connected between the output end and ground of the DC voltage booster circuit；
The controlling circuit of voltage regulation is connected to the DC voltage booster circuit, powers on rank in the liquid crystal display brightness regulating circuit
Section controls the DC voltage booster circuit and supply voltage is discontinuously increased to operating voltage for backlight.
5. liquid crystal display brightness regulating circuit according to claim 4, which is characterized in that
The filter capacitor is electrolytic capacitor.
6. liquid crystal display brightness regulating circuit according to claim 4, which is characterized in that
The controlling circuit of voltage regulation includes: the ON-OFF control circuit being connected between supply voltage and the DC voltage booster circuit；
The voltage value of the ON-OFF control circuit acquisition supply voltage breaks when the voltage value of supply voltage is lower than the first predeterminated voltage
The connection of switch power supply voltage and the DC voltage booster circuit restores when the voltage value of supply voltage is higher than the second predeterminated voltage
The connection of supply voltage and the DC voltage booster circuit.
7. liquid crystal display brightness regulating circuit according to claim 6, which is characterized in that
The ON-OFF control circuit includes pressure sampling circuit, comparator, switching regulator controller and switching tube, the switching tube string
It is associated between supply voltage and the DC voltage booster circuit；
The output end of the pressure sampling circuit connects the input terminal of the comparator；
The output end of the comparator connects the switching regulator controller；
The switching regulator controller controls the switching tube according to the comparison result of the comparator and disconnects or be connected.
8. liquid crystal display brightness regulating circuit according to claim 4, which is characterized in that
The controlling circuit of voltage regulation includes: signal output apparatus, and the output end of the signal output apparatus is connected to the direct current
The enable end of booster circuit, in the power up phase of the liquid crystal display brightness regulating circuit, the signal output apparatus passes through output
Pulse width modulating signal controls the DC voltage booster circuit interruption boosting.
9. liquid crystal display brightness regulating circuit according to claim 8, which is characterized in that
After the completion of the liquid crystal display brightness regulating circuit powers on, the signal output apparatus exports stable voltage control signal
Control the DC voltage booster circuit continuous work.
10. a kind of liquid crystal display, which is characterized in that the liquid crystal display is provided with -9 described in any item liquid crystal according to claim 1
Shield brightness regulating circuit.
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| CN201810842707.5A CN109036293A (en) | 2018-07-27 | 2018-07-27 | A kind of liquid crystal display brightness regulating circuit and a kind of liquid crystal display |
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| CN201810842707.5A CN109036293A (en) | 2018-07-27 | 2018-07-27 | A kind of liquid crystal display brightness regulating circuit and a kind of liquid crystal display |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111223457A (en) * | 2019-11-06 | 2020-06-02 | 昆山龙腾光电股份有限公司 | Backlight driving circuit and display device |
| CN112102788A (en) * | 2020-09-18 | 2020-12-18 | 深圳创维－Rgb电子有限公司 | Constant-current backlight output channel control system and display device |
| TWI774332B (en) * | 2020-04-29 | 2022-08-11 | 聯詠科技股份有限公司 | Display device and driver thereof |
| TWI796073B (en) * | 2021-12-30 | 2023-03-11 | 瑞軒科技股份有限公司 | Light-emitting diode device, operating method of the same, and display device |
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Application publication date: 20181218 |