CN109587423B - Backlight starting circuit - Google Patents
Backlight starting circuit Download PDFInfo
- Publication number
- CN109587423B CN109587423B CN201811140339.6A CN201811140339A CN109587423B CN 109587423 B CN109587423 B CN 109587423B CN 201811140339 A CN201811140339 A CN 201811140339A CN 109587423 B CN109587423 B CN 109587423B
- Authority
- CN
- China
- Prior art keywords
- power supply
- resistor
- backlight
- unit
- input end
- 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
- 238000002955 isolation Methods 0.000 claims description 53
- 239000003990 capacitor Substances 0.000 claims description 50
- 230000003287 optical effect Effects 0.000 claims description 8
- 230000000087 stabilizing effect Effects 0.000 claims description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 3
- 230000000740 bleeding effect Effects 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 102100039435 C-X-C motif chemokine 17 Human genes 0.000 description 1
- 101000889048 Homo sapiens C-X-C motif chemokine 17 Proteins 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
- H04N5/57—Control of contrast or brightness
-
- 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
Abstract
The invention belongs to the field of TV power supply drive control, and provides a backlight starting circuit, which comprises: a power supply timing control circuit and a soft start circuit; the power supply timing control circuit includes: a power control module and a power supply module; the power supply control module sends a power supply on signal to the power supply module when receiving a driving signal of external control equipment; the power supply module supplies power to the backlight device and the PFC circuit when receiving the power supply on signal, and the PFC circuit works; the soft start circuit includes: a delay module and a backlight control module; the delay module outputs driving voltage to the backlight control module when receiving the driving signal; the backlight control module receives preset voltage input by a preset reference power supply, and drives the backlight device to work when the driving voltage is smaller than the preset voltage. The invention can accurately control the starting time of the backlight device, meets the time sequence requirement of starting the PFC circuit and then starting the backlight device, avoids current overshoot, and has high reliability, few circuit elements and low cost.
Description
Technical Field
The invention belongs to the field of TV power drive control, and particularly relates to a backlight starting circuit.
Background
At present, a TV power supply backlight driving circuit mainly comprises a power factor correction circuit and a flyback backlight driving circuit. When the control signal is in high level, the power factor correction circuit works, then the internal voltage of the power factor correction circuit charges the capacitor slowly through the resistor, and when the voltage at two ends of the capacitor reaches the trigger voltage of the flyback backlight LED (Light Emitting Diode ) driving circuit, the backlight circuit starts to work, the delay precision of the circuit is poor, the delay time is easily influenced by the voltage of the PFC (Power Factor Correction ) circuit chip, and the additionally added soft start circuit also easily causes instability of the whole circuit, so that the backlight control circuit is poor in reliability and high in cost.
Disclosure of Invention
In view of the above, the invention provides a backlight starting circuit, which aims at solving the problems of poor time delay precision and high cost of a backlight control circuit in the prior art, so that the circuit reliability is poor.
An embodiment of the present invention provides a backlight start-up circuit including: the power supply timing control circuit and the soft start circuit are both suitable for being connected with external control equipment and a backlight device, the power supply timing control circuit is also suitable for being connected with the PFC circuit, and the power supply timing control circuit comprises: a power control module and a power supply module;
the power supply control module is connected with the power supply module and is used for sending a power supply conduction signal to the power supply module when receiving a driving signal of the external control equipment;
the power supply module is used for supplying power to the backlight device and the PFC circuit when receiving the power supply on signal so as to enable the PFC circuit to work;
the soft start circuit includes: a delay module and a backlight control module;
the delay module is connected with the backlight control module and is used for outputting driving voltage to the backlight control module when receiving the driving signal;
the backlight control module is suitable for being connected with a preset reference power supply and used for receiving preset voltage input by the preset reference power supply and driving the backlight device to work when the driving voltage is smaller than the preset voltage.
Optionally, the power control module includes: the input end, the output end, the first resistor, the second resistor, the third resistor, the first capacitor, the first triode and the first optocoupler switch;
the input end of the power supply control module is connected with the external control equipment, and the output end of the power supply control module is connected with the power supply module;
the base electrode of the first triode is connected with the input end of the power supply control module through the first resistor, the base electrode of the first triode is also connected with the emitting electrode of the first triode through the second resistor, the emitting electrode of the first triode is grounded, the collecting electrode of the first triode is connected with the primary side output end of the first opto-coupler switch, and the first capacitor is connected with the second resistor in parallel;
the primary side input end of the first optical coupler switch is connected with a first power supply through the third resistor, and the secondary side input end and the secondary side output end of the first optical coupler switch are both connected with the output end of the power supply control module.
Optionally, the power supply module includes: the input end, the output end, the fourth resistor, the fifth resistor, the sixth resistor, the second capacitor, the second triode, the first diode and the zener diode;
the input end of the power supply module is connected with the output end of the power supply control module, and the output end of the power supply module is respectively connected with the backlight device and the PFC circuit;
the base electrode of the second triode is respectively connected with the secondary side output end of the first opto-coupler switch, the cathode of the voltage stabilizing diode, the first end of the fifth resistor and the first end of the second capacitor, the emitter electrode of the second triode is connected with the anode of the first diode, and the collector electrode of the second triode is respectively connected with an external power supply, the cathode of the first diode and the first end of the fourth resistor;
the second end of the fourth resistor is connected with the secondary side input end of the first optocoupler switch; the anode of the voltage stabilizing diode, the second end of the fifth resistor and the second end of the second capacitor are grounded;
the anode of the first diode is suitable for being connected with the PFC circuit and is also suitable for being connected with the backlight device through the sixth resistor.
Optionally, the delay module includes: the device comprises an input end, an output end, a delay unit, an isolation unit and a discharge unit;
the input end of the delay module is connected with the external control equipment, and the output end of the delay module is connected with the backlight control module;
the input end of the delay unit is connected with the input end of the delay module, the output end of the delay unit is connected with the input end of the isolation unit and the input end of the discharge unit, and the delay unit is used for charging according to the driving signal and outputting a first voltage to the isolation unit;
the output end of the isolation unit is connected with the output end of the delay module and is used for isolating the first voltage and outputting the driving voltage to the backlight control module;
and the output end of the bleeder unit is connected with the input end of the isolation unit and is used for bleeding the voltage stored by the delay unit when the driving signal is at a low level.
Optionally, the delay unit includes: a first delay capacitor;
the positive electrode of the first delay capacitor is connected with the input end of the delay unit, and the negative electrode of the first delay capacitor is connected with the output end of the delay unit.
Optionally, the isolation unit includes: a first isolation diode;
the positive pole of the first isolation diode is connected with the input end of the isolation unit, and the negative pole of the first isolation diode is connected with the output end of the isolation unit.
Optionally, the bleed unit includes: the first bleeder resistor, the second bleeder resistor and the second isolation diode;
the first end of the first bleeder resistor is connected with the input end of the bleeder unit, and the second end of the first bleeder resistor is connected with the first end of the second bleeder resistor;
the second end of the second bleeder resistor is connected with the anode of the second isolation diode;
the negative pole of the second isolation diode is connected with the output end of the discharge unit.
Optionally, the backlight control module includes: the input end, the output end, the judging unit, the second optocoupler switch, the seventh resistor, the eighth resistor and the ninth resistor;
the input end of the backlight control module is connected with the delay module, the output end of the backlight control module is connected with the backlight device, the input end of the judging unit is connected with the input end of the backlight control module, the first voltage end of the judging unit is connected with an external power supply, the second voltage end of the judging unit is connected with the preset reference power supply, and the output end of the judging unit is connected with the primary side output end of the second optocoupler switch through the ninth resistor; the judging unit is used for comparing the driving voltage with the preset voltage;
the primary side input end of the second optical coupler switch is connected with an external power supply through the seventh resistor, and the eighth resistor is connected with the primary side of the second optical coupler switch in parallel; and the secondary side input end and the secondary side output end of the second optocoupler switch are connected with the output end of the backlight control module.
Optionally, the judging unit includes: the operational amplifier, the tenth resistor, the third capacitor and the fourth capacitor;
the positive phase input end of the operational amplifier is connected with the second voltage end of the judging unit, the negative phase input end of the operational amplifier is connected with the input end of the judging unit, the output end of the operational amplifier is connected with the output end of the judging unit, the positive power end of the operational amplifier is connected with the first voltage end of the judging unit, and the negative power end of the operational amplifier is grounded;
the first end of the third capacitor is connected with the negative phase input end of the operational amplifier, and the second end of the third capacitor is connected with the output end of the operational amplifier; the first end of the tenth resistor is connected with the negative phase input end of the operational amplifier, and the second end of the tenth resistor is connected with the output end of the operational amplifier through the fourth capacitor.
Compared with the prior art, the backlight starting circuit in the embodiment of the invention has the beneficial effects that: the power supply time sequence control circuit can provide voltage for the backlight device and the PFC circuit simultaneously, and has less circuit elements and low cost compared with the existing power supply time sequence control circuit; the backlight device is driven to work or not through judging the relation between the preset voltage and the driving voltage in the soft start circuit, namely, the backlight device does not work when the driving voltage is larger than the preset voltage, the backlight control module controls the backlight device to work when the driving voltage is smaller than the preset voltage, the starting time of the backlight device is accurately controlled through the relation between the preset voltage and the driving voltage, soft start is provided for the backlight device, the requirements of the PFC circuit for working first and then the backlight device are met, current overshoot is avoided, and reliability is high.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of a backlight start circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a power timing control circuit according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of a delay module according to an embodiment of the present invention;
FIG. 4 is a schematic circuit diagram of a soft start circuit according to an embodiment of the present invention;
fig. 5 is a schematic circuit diagram of another soft start circuit according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to illustrate the technical scheme of the invention, the following description is made by specific examples.
Referring to fig. 1, a backlight start-up circuit according to an embodiment of the present invention includes a power timing control circuit 100 and a soft start circuit 200. The power supply timing control circuit 100 and the soft start circuit 200 are both adapted to be connected to an external control device and a backlight apparatus, and the power supply timing control circuit 100 is also adapted to be connected to a PFC circuit.
Wherein, the power supply timing control circuit 100 includes: a power control module 110 and a power supply module 120. The power control module 110 is connected to the power supply module 120. The power control module 110 transmits a power on signal to the power supply module 120 upon receiving a driving signal of the external control device. The power supply module 120 supplies power to the backlight device and the PFC circuit when receiving the power on signal, so as to operate the PFC circuit.
The soft start circuit 200 includes: a delay module 210 and a backlight control module 220. The delay module 210 is connected with the backlight control module 220; the delay module 210 outputs a driving voltage to the backlight control module 220 when receiving the driving signal; the backlight control module 220 is adapted to be connected to a preset reference power supply, and is configured to receive a preset voltage input by the preset reference power supply, and drive the backlight device to work when the driving voltage is less than the preset voltage.
In practical applications, the power timing control circuit 100 receives the driving signal vbl_ctrl of the external control device, and simultaneously supplies power to the PFC circuit and the backlight device, and the PFC circuit operates at this time. The delay module 210 in the soft start circuit 200 outputs a driving voltage to the backlight control module 220 when receiving the driving signal vbl_ctrl, and the backlight control module 220 outputs an invalid signal when the driving voltage is greater than a preset voltage VREF, so that the backlight device does not work; when the driving voltage is less than the preset voltage VREF, the backlight control module 220 outputs a driving signal to the backlight device, and the backlight device operates. The process that the driving voltage is gradually smaller than the preset voltage VREF is realized, the PFC circuit is led in by the guide, the backlight device is started after the PFC circuit is started, current overshoot is avoided, the reliability is high, meanwhile, the time of the process that the driving voltage is gradually smaller than the preset voltage VREF is the starting time of the backlight device, and the accurate time delay is realized.
In the backlight starting circuit, the power supply time sequence control circuit 100 can provide voltages for the backlight device and the PFC circuit simultaneously, and has less circuit elements and low cost compared with the conventional power supply time sequence control circuit; the soft start circuit 200 is used for judging whether the backlight device works or not according to the relation between the preset voltage and the driving voltage, namely, the backlight device does not work when the driving voltage is larger than the preset voltage, and works when the driving voltage is smaller than the preset voltage, the starting time of the backlight device is accurately controlled according to the relation between the preset voltage and the driving voltage, soft start is provided for the backlight device, the requirements of the PFC circuit that the backlight device works first and then works are met, current overshoot is avoided, and reliability is high.
In one embodiment, referring to FIG. 2, the power control module 110 includes: the input end, the output end, the first resistor R1, the second resistor R2, the third resistor R3, the first capacitor C1, the first triode Q1 and the first optocoupler switch PUB.
The input end of the power control module 110 is connected with external control equipment, and the output end of the power control module 110 is connected with the power supply module 120.
The base of the first triode Q1 is connected with the input end of the power supply control module 110 through the first resistor R1, the base of the first triode Q1 is also connected with the emitter of the first triode Q1 through the second resistor R2, the emitter of the first triode Q1 is grounded, the collector of the first triode Q1 is connected with the primary side output end of the first opto-coupler switch PUB, and the first capacitor C1 is connected with the second resistor R2 in parallel.
The primary side input end of the first optocoupler switch PUB is connected with a first power source (+ 12V) through a third resistor R3, and the secondary side input end and the secondary side output end of the first optocoupler switch PUB are both connected with the output end of the power control module 110.
In one embodiment, referring to fig. 2, the power module 120 includes: the input end, the output end, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a second capacitor C2, a second triode Q2, a first diode D1 and a zener diode Z1.
The input end of the power supply module 120 is connected with the output end of the power supply control module 110, and the output end of the power supply module 120 is respectively connected with the backlight device LED and the PFC circuit.
The base electrode of the second triode Q2 is respectively connected with the secondary side output end of the first optocoupler switch PUB, the cathode of the voltage stabilizing diode Z1, the first end of the fifth resistor R5 and the first end of the second capacitor C2, the emitter electrode of the second triode Q2 is connected with the anode of the first diode C1, and the collector electrode of the second triode Q2 is respectively connected with the external power supply VCC1, the cathode of the first diode D1 and the first end of the fourth resistor R4.
The second end of the fourth resistor R4 is connected with the secondary side input end of the first optocoupler switch PUB; the anode of the zener diode Z1, the second end of the fifth resistor R5 and the second end of the second capacitor C2 are all grounded. The anode of the first diode D1 is adapted to be connected to said PFC circuit and also to the backlight LED via a sixth resistor R6.
In one embodiment, referring to fig. 3, the delay module 210 includes: an input, an output, a delay unit 211, an isolation unit 212 and a bleed unit 213.
The input end of the delay module 210 is connected with an external control device, and the output end of the delay module 210 is connected with the backlight control module 220.
An input terminal of the delay unit 211 is connected to an input terminal of the delay module 210, and an output terminal of the delay unit 211 is connected to an input terminal of the isolation unit 212 and an input terminal of the bleeder unit 213, for charging according to the driving signal vbl_ctrl, and outputting a first voltage to the isolation unit 212.
The output end of the isolation unit 212 is connected to the output end of the delay module 210, and is configured to isolate the first voltage and output the driving voltage to the backlight control module 220.
An output terminal of the bleeder unit 213 is connected to an input terminal of the isolation unit 212 for bleeding off the voltage stored by the delay unit 211 when the driving signal is low.
When the delay unit 211 receives the driving signal vbl_ctrl, the voltage output to the isolation unit 212 is relatively large, and since the delay unit 211 is charged, the voltage at both ends will increase, and the voltage output to the isolation unit 212 will also decrease, and when the reduced voltage is smaller than the preset voltage, the backlight control module 220 drives the backlight device to work, so as to implement delay, and the delay time can be determined by the charging time of the delay unit 211.
In one embodiment, referring to fig. 3, the delay unit 211 includes: a first delay capacitance SE1.
The positive electrode of the first delay capacitor SE1 is connected with the input end of the delay unit 211, and the negative electrode of the first delay capacitor SE1 is connected with the output end of the delay unit 211.
In one embodiment, referring to fig. 3, the isolation unit 212 includes: a first isolation diode SD1.
The positive electrode of the first isolation diode SD1 is connected to the input terminal of the isolation unit 212, and the negative electrode of the first isolation diode SD1 is connected to the output terminal of the isolation unit 212. The first isolation diode SD1 can avoid the influence of the delay unit 211 on the current loop.
In one embodiment, referring to fig. 3, the bleed unit 213 includes: a first bleeder resistor SR1, a second bleeder resistor SR2 and a second isolation diode SD2.
A first end of the first bleeder resistor SR1 is connected to the input end of the bleeder unit 213, and a second end of the first bleeder resistor SR1 is connected to a first end of the second bleeder resistor SR 2; the second end of the second bleeder resistor SR2 is connected with the anode of the second isolation diode SD 2; the cathode of the second isolation diode SD2 is connected to the output of the bleeder unit 213. The first bleeder resistor SR1 may ensure that the isolation unit 212 is completely turned off when the driving signal is at a high level; the second bleeder resistor SR2 and the second isolation diode SD2 form a bleeder circuit, and when the driving signal is at a low level, the voltage on the delay unit 211 can be quickly discharged.
The first delay capacitor SE1 can charge when the driving signal is at a high level, and simultaneously outputs a preset voltage to the isolation unit 212, and as the voltage at two ends of the first delay capacitor SE1 increases, the preset voltage decreases, and as the driving signal voltage is fixed, the capacity of the first delay capacitor SE1 is fixed, so that the delay time of the first delay capacitor SE1 is accurate, the slow charging process of the first delay capacitor SE1 is utilized, the requirements of the PFC circuit for working first and the backlight device for working later are met, the starting soft start of the backlight device is realized, the current overshoot is avoided, and the system stability is improved.
In one embodiment, referring to fig. 4, the backlight control module 220 includes: an input terminal, an output terminal, a judging unit 221, a second optocoupler switch SU2B, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9.
The input end of the backlight control module 220 is connected with the delay module 210, and the output end of the backlight control module 220 is connected with the backlight device LED.
An input end of the judging unit 221 is connected with an input end of the backlight control module 220, a first voltage end of the judging unit 221 is connected with an external power supply (+ 12V), a second voltage end of the judging unit 221 is connected with a preset reference power supply, and an output end of the judging unit 221 is connected with a primary side output end of the second optocoupler switch SU2B through a ninth resistor R9; the judging unit 221 is configured to compare the driving voltage with a preset voltage VREF, and drive the backlight device to operate when the driving voltage is less than the preset voltage VREF.
The primary side input end of the second optocoupler switch SU2B is connected with an external power supply (+ 12V) through a seventh resistor R7, and an eighth resistor R8 is connected with the primary side of the second optocoupler switch SU2B in parallel; the secondary side input end and the secondary side output end of the second optocoupler switch SU2B are connected with the output end of the backlight control module 220, that is, the secondary side input end and the secondary side output end of the second optocoupler switch SU2B are connected with the backlight device.
In one embodiment, referring to fig. 4 and 5, the judging unit 221 includes: an operational amplifier SU1B, a tenth resistor R10, a third capacitor C3, and a fourth capacitor C4.
The positive phase input end of the operational amplifier SU1B is connected with the second voltage end of the judging unit 221, the negative phase input end of the operational amplifier SU1B is connected with the input end of the judging unit 221, the output end of the operational amplifier SU1B is connected with the output end of the judging unit 221, the positive power end of the operational amplifier SU1B is connected with the first voltage end of the judging unit 221, and the negative power end of the operational amplifier SU1B is grounded.
The first end of the third capacitor C3 is connected with the negative phase input end of the operational amplifier SU1B, and the second end of the third capacitor C3 is connected with the output end of the operational amplifier SU 1B; the first end of the tenth resistor R10 is connected with the negative phase input end of the operational amplifier SU1B, and the second end of the tenth resistor R10 is connected with the output end of the operational amplifier SU1B through a fourth capacitor C4.
Specifically, the positive power supply end of the operational amplifier SU1B receives a +12v power supply, the positive power supply end of the operational amplifier SU1B receives a preset voltage VREF of a preset reference power supply, the second optocoupler switch SU2B receives the +12v power supply and is turned on, at this time, the power supply timing control circuit 100 supplies power to the backlight device and the PFC circuit, and the PFC circuit works. Because the delay unit 211, the driving voltage is greater than the preset voltage VREF, the output end of the operational amplifier SU1B outputs an invalid signal, and the backlight device does not work; when the driving voltage is smaller than the preset voltage VREF, the output end of the operational amplifier SU1B outputs a driving signal to the backlight device, so that the PFC circuit works first and then the backlight device is started, current overshoot is avoided, and the reliability is high.
In one embodiment, referring to fig. 5, the soft start circuit 200 further comprises: resistor R11, resistor Ra1, resistor Ra2, resistor Ra3, resistor Ra4, resistor Ra5, and diode SD3.
The first end of the resistor R11 is connected to the input end of the backlight control module 220, and the second end of the resistor R11 is respectively connected to the backlight sampling end (LED-), the first end of the resistor Ra1, the first end of the resistor Ra2, the first end of the resistor Ra3, the first end of the resistor Ra4, the first end of the resistor Ra5, and the anode of the diode SD3, and the second end of the resistor Ra1, the second end of the resistor Ra2, the second end of the resistor Ra3, the second end of the resistor Ra4, the second end of the resistor Ra5, and the cathode of the diode SD3 are all grounded. The backlight sampling end (LED-) can sample the voltage of the backlight device to obtain the voltage information of the backlight device.
The operation principle of the backlight start-up circuit of the present embodiment is described in detail below with reference to the specific circuit structure of the backlight start-up circuit in the above embodiment:
referring to fig. 2 and 4, the external control device transmits a driving signal vbl_ctrl. When the driving signal vbl_ctrl is at a high level, the first optocoupler switch PUB is turned on, and the power supply module 120 provides the voltage pfc_vcc for the PFC circuit, and provides the voltage led_vcc for the backlight device, so that the PFC circuit works; meanwhile, the first delay capacitor SE1 is charged, and the first isolation diode SD1 isolates the voltage output by the first delay capacitor SE1 and outputs the first voltage to the backlight control module 220; when the driving signal vbl_ctrl is at a low level, the first bleeder resistor SR1, the second bleeder resistor SR2 and the second isolation diode SD2 rapidly discharge the voltage on the first delay capacitor SE1.
When the driving signal vbl_ctrl is at a high level, for example, the voltage of the driving signal vbl_ctrl is 3.3V, the first delay capacitor SE1 charges and outputs a first voltage, the first voltage inputs the driving voltage to the negative phase input end of the operational amplifier SU1B through the first isolation diode SD1, at this time, the voltage of the negative phase input end of the operational amplifier SU1B is greater than the preset voltage VREF of the positive phase input end, the output end of the operational amplifier SU1B outputs a low level, that is, an invalid signal, and the backlight device does not work; along with the rising of the voltages at the two ends of the first delay capacitor SE1, the voltage of the negative phase input end of the operational amplifier SU1B gradually decreases until the preset voltage VREF at the input end of the operational amplifier SU1B is smaller than the preset voltage VREF at the input end of the operational amplifier Yu Zhengxiang, the output end of the operational amplifier SU1B outputs a high level (driving signal), at this time, the second opto-coupler switch SU2B receives +12V voltage to conduct, and the backlight device is driven to work according to the driving signal.
In the above embodiment, the power supply time sequence control circuit can provide voltages for the backlight device and the PFC circuit at the same time, and has less circuit elements and low cost compared with the existing power supply time sequence control circuit; the backlight device is driven to work through judging the relation between the preset voltage and the driving voltage in the soft start circuit, namely, the backlight device does not work when the driving voltage is larger than the preset voltage, the backlight control module drives the backlight device to work when the driving voltage is smaller than the preset voltage, the starting time of the backlight device is accurately controlled through the relation between the preset voltage and the driving voltage, soft start is provided for the backlight device, the requirements of the PFC circuit for working first and then the backlight device are met, current overshoot is avoided, and reliability is high.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (8)
1. A backlight start-up circuit, including power supply timing control circuit and soft start-up circuit, power supply timing control circuit with soft start-up circuit all is suitable for being connected with external control equipment and backlight unit, power supply timing control circuit still is suitable for being connected with power factor correction PFC circuit, its characterized in that, power supply timing control circuit includes: a power control module and a power supply module;
the power supply control module is connected with the power supply module and is used for sending a power supply conduction signal to the power supply module when receiving a driving signal of the external control equipment;
the power supply module is used for supplying power to the backlight device and the PFC circuit when receiving the power supply on signal so as to enable the PFC circuit to work;
the soft start circuit includes: a delay module and a backlight control module;
the delay module is connected with the backlight control module and is used for outputting driving voltage to the backlight control module when receiving the driving signal;
the backlight control module is suitable for being connected with a preset reference power supply and used for receiving preset voltage input by the preset reference power supply and driving the backlight device to work when the driving voltage is smaller than the preset voltage;
the delay module comprises: the device comprises an input end, an output end, a delay unit, an isolation unit and a discharge unit;
the input end of the delay module is connected with the external control equipment, and the output end of the delay module is connected with the backlight control module;
the input end of the delay unit is connected with the input end of the delay module, the output end of the delay unit is connected with the input end of the isolation unit and the input end of the discharge unit, and the delay unit is used for charging according to the driving signal and outputting a first voltage to the isolation unit;
the output end of the isolation unit is connected with the output end of the delay module and is used for isolating the first voltage and outputting the driving voltage to the backlight control module;
the output end of the bleeder unit is connected with the input end of the isolation unit and is used for bleeder the voltage stored by the delay unit when the driving signal is at a low level;
when the delay unit receives the driving signal, the voltage output to the isolation unit is relatively large, and the voltage at two ends can be increased due to the fact that the delay unit is charged, the voltage output to the isolation unit can be reduced, when the reduced voltage is smaller than the preset voltage, the backlight control module drives the backlight device to work, delay is achieved, and the delay time can be determined by the charging time of the delay unit.
2. The backlight start-up circuit of claim 1, wherein the power control module comprises: the input end, the output end, the first resistor, the second resistor, the third resistor, the first capacitor, the first triode and the first optocoupler switch;
the input end of the power supply control module is connected with the external control equipment, and the output end of the power supply control module is connected with the power supply module;
the base electrode of the first triode is connected with the input end of the power supply control module through the first resistor, the base electrode of the first triode is also connected with the emitting electrode of the first triode through the second resistor, the emitting electrode of the first triode is grounded, the collecting electrode of the first triode is connected with the primary side output end of the first opto-coupler switch, and the first capacitor is connected with the second resistor in parallel;
the primary side input end of the first optical coupler switch is connected with a first power supply through the third resistor, and the secondary side input end and the secondary side output end of the first optical coupler switch are both connected with the output end of the power supply control module.
3. The backlight start-up circuit of claim 2, wherein the power supply module comprises: the input end, the output end, the fourth resistor, the fifth resistor, the sixth resistor, the second capacitor, the second triode, the first diode and the zener diode;
the input end of the power supply module is connected with the output end of the power supply control module, and the output end of the power supply module is respectively connected with the backlight device and the PFC circuit;
the base electrode of the second triode is respectively connected with the secondary side output end of the first opto-coupler switch, the cathode of the voltage stabilizing diode, the first end of the fifth resistor and the first end of the second capacitor, the emitter electrode of the second triode is connected with the anode of the first diode, and the collector electrode of the second triode is respectively connected with an external power supply, the cathode of the first diode and the first end of the fourth resistor;
the second end of the fourth resistor is connected with the secondary side input end of the first optocoupler switch; the anode of the voltage stabilizing diode, the second end of the fifth resistor and the second end of the second capacitor are grounded;
the anode of the first diode is suitable for being connected with the PFC circuit and is also suitable for being connected with the backlight device through the sixth resistor.
4. The backlight start-up circuit of claim 1, wherein the delay unit comprises: a first delay capacitor;
the positive electrode of the first delay capacitor is connected with the input end of the delay unit, and the negative electrode of the first delay capacitor is connected with the output end of the delay unit.
5. The backlight start-up circuit of claim 1, wherein the isolation unit comprises: a first isolation diode;
the positive pole of the first isolation diode is connected with the input end of the isolation unit, and the negative pole of the first isolation diode is connected with the output end of the isolation unit.
6. The backlight start-up circuit of claim 1, wherein the bleed unit comprises: the first bleeder resistor, the second bleeder resistor and the second isolation diode;
the first end of the first bleeder resistor is connected with the input end of the bleeder unit, and the second end of the first bleeder resistor is connected with the first end of the second bleeder resistor;
the second end of the second bleeder resistor is connected with the anode of the second isolation diode;
the negative pole of the second isolation diode is connected with the output end of the discharge unit.
7. The backlight start-up circuit of any one of claims 1 to 6, wherein the backlight control module comprises: the input end, the output end, the judging unit, the second optocoupler switch, the seventh resistor, the eighth resistor and the ninth resistor;
the input end of the backlight control module is connected with the delay module, the output end of the backlight control module is connected with the backlight device, the input end of the judging unit is connected with the input end of the backlight control module, the first voltage end of the judging unit is connected with an external power supply, the second voltage end of the judging unit is connected with the preset reference power supply, and the output end of the judging unit is connected with the primary side output end of the second optocoupler switch through the ninth resistor; the judging unit is used for comparing the driving voltage with the preset voltage;
the primary side input end of the second optical coupler switch is connected with an external power supply through the seventh resistor, and the eighth resistor is connected with the primary side of the second optical coupler switch in parallel; and the secondary side input end and the secondary side output end of the second optocoupler switch are connected with the output end of the backlight control module.
8. The backlight start-up circuit according to claim 7, wherein the judging unit comprises: the operational amplifier, the tenth resistor, the third capacitor and the fourth capacitor;
the positive phase input end of the operational amplifier is connected with the second voltage end of the judging unit, the negative phase input end of the operational amplifier is connected with the input end of the judging unit, the output end of the operational amplifier is connected with the output end of the judging unit, the positive power end of the operational amplifier is connected with the first voltage end of the judging unit, and the negative power end of the operational amplifier is grounded;
the first end of the third capacitor is connected with the negative phase input end of the operational amplifier, and the second end of the third capacitor is connected with the output end of the operational amplifier; the first end of the tenth resistor is connected with the negative phase input end of the operational amplifier, and the second end of the tenth resistor is connected with the output end of the operational amplifier through the fourth capacitor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811140339.6A CN109587423B (en) | 2018-09-28 | 2018-09-28 | Backlight starting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811140339.6A CN109587423B (en) | 2018-09-28 | 2018-09-28 | Backlight starting circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109587423A CN109587423A (en) | 2019-04-05 |
| CN109587423B true CN109587423B (en) | 2023-11-21 |
Family
ID=65919958
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811140339.6A Active CN109587423B (en) | 2018-09-28 | 2018-09-28 | Backlight starting circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109587423B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112185305B (en) * | 2019-07-04 | 2022-04-12 | 京东方科技集团股份有限公司 | Backlight control device, backlight control method and display device |
| CN115225071A (en) * | 2022-09-15 | 2022-10-21 | 荣耀终端有限公司 | Power supply circuit and electronic equipment |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110072064A (en) * | 2009-12-22 | 2011-06-29 | 엘지디스플레이 주식회사 | Back light unit and liquid crystal display device using the same |
| KR20110138524A (en) * | 2010-06-21 | 2011-12-28 | 엘지디스플레이 주식회사 | Liquid crystal display device and driving method thereof |
| WO2014180054A1 (en) * | 2013-05-08 | 2014-11-13 | 深圳市华星光电技术有限公司 | Led backlight driving circuit and driving method therefor, and liquid crystal display apparatus |
| JP2014240854A (en) * | 2013-06-11 | 2014-12-25 | シャープ株式会社 | Liquid crystal display device and television device |
| JP2015191809A (en) * | 2014-03-28 | 2015-11-02 | 船井電機株式会社 | Backlight device and display device |
| CN205069083U (en) * | 2015-10-22 | 2016-03-02 | 广州视源电子科技股份有限公司 | Prevent circuit that overshoots |
| CN106787739A (en) * | 2017-03-28 | 2017-05-31 | 深圳Tcl新技术有限公司 | Produce the power-supplying circuit and power circuit of sequential |
| CN207337882U (en) * | 2017-08-21 | 2018-05-08 | 深圳Tcl新技术有限公司 | Sequential control circuit and backlight electric power |
| CN207690477U (en) * | 2017-12-21 | 2018-08-03 | 广州龙之杰科技有限公司 | Integrated device a kind of while that there is backlight delay and backlight illumination control |
| CN108574260A (en) * | 2017-03-10 | 2018-09-25 | 厦门歌乐电子企业有限公司 | A kind of backlight module power protecting circuit and mobile unit |
| CN208724068U (en) * | 2018-09-28 | 2019-04-09 | 深圳市鼎盛光电有限公司 | Back-light starting circuit |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI441143B (en) * | 2007-06-13 | 2014-06-11 | Niko Semiconductor Co Ltd | The primary driving control inverter for backlight of lcd panel |
| CN102810299B (en) * | 2011-06-03 | 2015-06-03 | 乐金显示有限公司 | Backlight unit and method for driving the same |
| JP6091178B2 (en) * | 2012-01-31 | 2017-03-08 | キヤノン株式会社 | LIGHT SOURCE DEVICE, ELECTRONIC DEVICE, AND CONTROL METHOD THEREOF |
-
2018
- 2018-09-28 CN CN201811140339.6A patent/CN109587423B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110072064A (en) * | 2009-12-22 | 2011-06-29 | 엘지디스플레이 주식회사 | Back light unit and liquid crystal display device using the same |
| KR20110138524A (en) * | 2010-06-21 | 2011-12-28 | 엘지디스플레이 주식회사 | Liquid crystal display device and driving method thereof |
| WO2014180054A1 (en) * | 2013-05-08 | 2014-11-13 | 深圳市华星光电技术有限公司 | Led backlight driving circuit and driving method therefor, and liquid crystal display apparatus |
| JP2014240854A (en) * | 2013-06-11 | 2014-12-25 | シャープ株式会社 | Liquid crystal display device and television device |
| JP2015191809A (en) * | 2014-03-28 | 2015-11-02 | 船井電機株式会社 | Backlight device and display device |
| CN205069083U (en) * | 2015-10-22 | 2016-03-02 | 广州视源电子科技股份有限公司 | Prevent circuit that overshoots |
| CN108574260A (en) * | 2017-03-10 | 2018-09-25 | 厦门歌乐电子企业有限公司 | A kind of backlight module power protecting circuit and mobile unit |
| CN106787739A (en) * | 2017-03-28 | 2017-05-31 | 深圳Tcl新技术有限公司 | Produce the power-supplying circuit and power circuit of sequential |
| CN207337882U (en) * | 2017-08-21 | 2018-05-08 | 深圳Tcl新技术有限公司 | Sequential control circuit and backlight electric power |
| CN207690477U (en) * | 2017-12-21 | 2018-08-03 | 广州龙之杰科技有限公司 | Integrated device a kind of while that there is backlight delay and backlight illumination control |
| CN208724068U (en) * | 2018-09-28 | 2019-04-09 | 深圳市鼎盛光电有限公司 | Back-light starting circuit |
Non-Patent Citations (2)
| Title |
|---|
| Design rule and system parameters compare between multi-phase and multi-lamp PWM dimming control for backlight inverter;Chien-Yeh Ho 等;《IEEE》;全文 * |
| LED电视大尺寸多灯条高效背光驱动和电源一体化技术的设计与实现;刘广学;《中国优秀硕士学位论全文数据库电子期刊》;全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109587423A (en) | 2019-04-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11824396B2 (en) | Wireless charging method, electronic device and wireless charging apparatus | |
| US7586346B2 (en) | Power good signal generating circuit | |
| US10008944B2 (en) | Control method and control circuit for switching power supply | |
| CN109587423B (en) | Backlight starting circuit | |
| CN102076151A (en) | High-efficiency light emitting diode (LED) drive circuit and drive method | |
| US20170229051A1 (en) | High-power power supply for use with display devices and associated display device | |
| CN109597701A (en) | A kind of device that communication module is restarted automatically | |
| CN103683890A (en) | Flyback quick starting drive circuit and drive method | |
| US20140292202A1 (en) | LED Backlight Driving Circuit and Backlight Module | |
| US11071180B2 (en) | Lighting unit and driving method | |
| CN208724068U (en) | Back-light starting circuit | |
| WO2023246506A1 (en) | Starting control circuit and switching power source system | |
| US10212383B2 (en) | Standby control circuit and display device | |
| CN109459607B (en) | Isolated accurate zero-crossing detection circuit | |
| CN108594082B (en) | Power-down signal transmission circuit and method for commercial power | |
| CN109412436B (en) | Synchronous rectification control chip and circuit | |
| CN211606889U (en) | Overvoltage protection circuit, constant current drive circuit, drive integrated circuit board and electronic equipment | |
| CN103415118B (en) | Backlight drive circuit, electronic installation and backlight driving method | |
| CN209994594U (en) | Control circuit for fixing discharge time | |
| CN203072221U (en) | Primary side feedback constant current control circuit | |
| CN106932676B (en) | Transformer substation comprehensive test system based on ZYNQ platform | |
| CN206442360U (en) | A kind of triggers circuit of non-contact voltage stabilizer controllable silicon | |
| CN215268078U (en) | Flyback quasi-resonant circuit | |
| CN108572686B (en) | Constant current device applied to AC-DC system | |
| CN113110146B (en) | Driving power supply circuit and driving method thereof |
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 | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |