CN109475026B - Digital studio surface light source circuit - Google Patents
Digital studio surface light source circuit Download PDFInfo
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- CN109475026B CN109475026B CN201811324025.1A CN201811324025A CN109475026B CN 109475026 B CN109475026 B CN 109475026B CN 201811324025 A CN201811324025 A CN 201811324025A CN 109475026 B CN109475026 B CN 109475026B
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/10—Controlling the intensity of the light
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
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Abstract
A digital shadow mask light source circuit, comprising: the LED lamp comprises a DC power supply for providing direct current, at least one DC-DC dimming device for receiving the direct current and performing asynchronous rectification on the direct current, and at least one group of light sources for receiving the direct current after the asynchronous rectification to emit light; the DC-DC dimming device is electrically connected with the DC power supply and the light source respectively. The surface light source circuit of the digital studio can realize transient highlight and non-stroboscopic light source control by adopting the DC power supply and the DC-DC dimming device with asynchronous rectification, so that the instantaneously highlighted LED light can be synchronously output when shooting is conducted in the shooting process of the digital studio.
Description
Technical Field
The invention relates to the field of photography, in particular to a digital shadow shed light source circuit.
Background
The existing digital studio system basically adopts canvas to match with the traditional lighting technology for shooting. Because the digital studio occupies a large area, has high height, dark environment and the like, a plurality of groups of high-power LED lamps need to be matched. However, prior art digital studios typically use existing common lighting LED lamp driver circuits to drive the multiple sets of high power LED lamps. Therefore, the requirement that the instantaneously highlighted LED light needs to be synchronously output when shooting lightning in the digital studio shooting process cannot be met.
Disclosure of Invention
The present invention is directed to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a digital studio light source circuit, which can synchronously output instantly highlighted LED lights during flash triggering during shooting in a digital studio.
The technical scheme adopted by the invention for solving the technical problems is as follows: a digital shadow mask light source circuit is constructed, comprising: the LED lamp comprises a DC power supply for providing direct current, at least one DC-DC dimming device for receiving the direct current and performing asynchronous rectification on the direct current, and at least one group of light sources for receiving the direct current after the asynchronous rectification to emit light; the DC-DC dimming device is electrically connected with the DC power supply and the light source respectively.
In the digital studio surface light source circuit of the present invention, the DC-DC dimming device includes a step-down DC-DC module electrically connected to the DC power supply to receive the direct current and perform step-down conversion on the direct current, and a first transient dimming control module electrically connected to the step-down DC-DC module to perform transient dimming control on the direct current after the step-down conversion.
In the area light source circuit of the digital studio, the buck DC-DC module includes a first buck DC-DC chip, a second buck DC-DC chip, a first MOS transistor and a first inductor, an input end of the first buck DC-DC chip is connected to the DC power supply, an output end of the first buck DC-DC chip is connected to a first input end of the second buck DC-DC chip, a first output end of the second buck DC-DC chip is connected to an input end of the first transient dimming control module, a second input end of the second buck DC-DC chip is connected to a feedback end of the first transient dimming control module, a second output end of the second buck DC-DC chip is connected to a gate of the first MOS transistor, a source of the first MOS transistor is connected to the light source via the first inductor, and a drain of the second buck DC-DC chip is connected to the DC power supply.
In the digital studio surface light source circuit of the present invention, the first transient dimming control module includes: the first constant-voltage transient dimming control unit is electrically connected with the first output end of the second buck DC-DC chip and the light source respectively, the first constant-current transient dimming control unit is electrically connected with the first output end of the second buck DC-DC chip and the light source respectively, and the first RC integral feedback unit is electrically connected with the second input end of the second buck DC-DC chip and the light source respectively.
In the area light source circuit of the digital studio, the first constant voltage transient dimming control unit comprises a first diode, a first constant voltage operational amplifier, a first rectifier diode, a first resistor and a second resistor, wherein the anode of the first diode is connected with the first input end of the second buck DC-DC chip, the cathode of the first diode is connected with the output end of the first constant voltage operational amplifier, the positive input end of the first constant voltage operational amplifier is connected with the first constant current transient dimming control unit and the cathode of the first rectifier diode, the anode of the first rectifier diode is grounded, and the reverse input end of the first constant voltage operational amplifier is grounded through the first resistor and connected with the light source through the second resistor respectively; the first constant-current transient dimming control unit comprises a second diode, a first constant-current operational amplifier, a third resistor and a fourth resistor, wherein the anode of the second diode is connected with the first input end of the second buck DC-DC chip, the cathode of the second diode is connected with the output end of the first constant-current operational amplifier, the reverse input end of the first constant-current operational amplifier is connected with the light source through the third resistor, and the forward input end of the first constant-current operational amplifier is connected with the first constant-voltage transient dimming control unit through the fourth resistor.
In the digital studio surface light source circuit of the present invention, the DC-DC dimming device includes a boost DC-DC module electrically connected to the DC power supply to receive the direct current and perform boost conversion on the direct current, and a second transient dimming control module electrically connected to the boost DC-DC module to perform transient dimming control on the direct current after the boost conversion.
In the area light source circuit of digital studio of the present invention, the boost DC-DC module includes a third buck DC-DC chip, a boost DC-DC chip, a second MOS transistor, a second inductor, a third MOS transistor, a third diode, and a switching transistor, wherein an input terminal of the third buck DC-DC chip is connected to the DC power supply, an output terminal thereof is connected to the first input terminal of the boost DC-DC chip, a gate of the second MOS transistor is connected to a collector of the switching transistor, an emitter of the switching transistor is grounded, a source thereof is connected to the feedback terminal of the second transient dimming control module, a drain thereof is connected to the DC power supply, a source thereof is connected to the anode of the third diode via the second inductor, a second input terminal of the boost DC-DC chip is connected to the feedback terminal of the second transient dimming control module, and a second output terminal of the boost DC-DC chip is connected to the source and the gate thereof, the drain electrode of the third MOS tube is connected with the anode of the third diode, and the cathode of the third diode is connected with the light source.
In the above-described circuit for a planar light source of a digital studio, the second transient dimming control module comprises: the second constant-voltage transient dimming control unit is electrically connected with the first input end of the boost DC-DC chip and the light source respectively, the second constant-current transient dimming control unit is electrically connected with the first output end of the boost DC-DC chip and the light source respectively, and the second RC integral feedback unit is electrically connected with the second input end of the boost DC-DC chip and the light source respectively.
In the area light source circuit of the digital studio, the second constant voltage transient dimming control unit comprises a fourth diode, a second constant voltage operational amplifier, a third rectifier diode, a fifth resistor and a sixth resistor, wherein the anode of the fourth diode is connected with the second input end of the boost DC-DC chip, the cathode of the fourth diode is connected with the output end of the second constant voltage operational amplifier, the positive input end of the second constant voltage operational amplifier is connected with the constant current transient dimming control unit and the cathode of the third rectifier diode, the anode of the third rectifier diode is grounded, and the reverse input end of the second constant voltage operational amplifier is grounded through the fifth resistor and connected with the light source through the sixth resistor respectively; the constant-current transient dimming control unit comprises a fifth diode, a second constant-current operational amplifier, a seventh resistor and an eighth resistor, wherein the anode of the fifth diode is connected with the second input end of the boosting DC-DC chip, the cathode of the fifth diode is connected with the output end of the second constant-current operational amplifier, the reverse input end of the second constant-current operational amplifier is connected with the light source through the seventh resistor, and the forward input end of the second constant-current operational amplifier is connected with the second constant-voltage transient dimming control unit through the eighth resistor.
In the area light source circuit of the digital studio, the DC-DC dimming device further includes a boost overcurrent protection module and/or a buck overcurrent protection module connected to the boost DC-DC module and/or the buck DC-DC module.
The surface light source circuit of the digital studio can realize transient highlight and non-stroboscopic light source control by adopting the DC power supply and the DC-DC dimming device with asynchronous rectification, so that the instantaneously highlighted LED light can be synchronously output when shooting is conducted in the shooting process of the digital studio.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
fig. 1 is a schematic block diagram of a first embodiment of a digital studio plane light source circuit of the present invention;
fig. 2 is a functional block diagram of a second embodiment of the digital studio plane light source circuit of the present invention;
fig. 3 is a partial circuit schematic diagram of a third embodiment of the DC-DC dimming device of the digital studio plane light source circuit of the present invention;
fig. 4 is a partial circuit schematic diagram of a fourth embodiment of the DC-DC dimming device of the digital studio plane light source circuit of the present invention;
fig. 5 is a partial circuit schematic diagram of a fourth embodiment of the DC-DC dimming device of the digital studio surface light source circuit of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention relates to a digital shadow shed light source circuit, comprising: the LED lamp comprises a DC power supply for providing direct current, at least one DC-DC dimming device for receiving the direct current and performing asynchronous rectification on the direct current, and at least one group of light sources for receiving the direct current after the asynchronous rectification to emit light; the DC-DC dimming device is electrically connected with the DC power supply and the light source respectively. The surface light source circuit of the digital studio can realize transient highlight and non-stroboscopic light source control by adopting the DC power supply and the DC-DC dimming device with asynchronous rectification, so that the instantaneously highlighted LED light can be synchronously output when shooting is conducted in the shooting process of the digital studio.
Fig. 1 is a schematic block diagram of a first embodiment of a digital studio plane light source circuit of the present invention. As shown in fig. 1, the digital studio surface light source circuit of the present invention includes a DC power supply 100 for supplying a direct current, at least one DC-DC dimming device 200 for receiving the direct current and performing asynchronous rectification on the direct current, and at least one set of light sources 300 for receiving the asynchronous rectified direct current to emit light; the DC-DC dimming device 200 is electrically connected to the DC power source 100 and the light source 300, respectively.
In a preferred embodiment of the present invention, the DC power supply 100 may be a high resolution (or stepless) DC-DC adjustable constant current and voltage power supply using a buck (boost) mode. In another preferred embodiment of the invention, the DC power supply 100 may comprise an AC-DC converter for receiving an alternating mains current and converting the received alternating mains current into a direct current.
In a preferred embodiment of the present invention, the DC-DC dimming device 200 can be constructed using any DC-DC dimming device known in the art. For example, the controller may include a buck DC-DC module and/or a boost DC-DC module, and a transient dimming control module electrically connected to the buck DC-DC module and/or the boost DC-DC module, respectively. Of course, in other preferred embodiments of the present invention, other light source dimming devices or circuits may be used to construct the DC-DC dimming device 200. In a preferred embodiment of the present invention, a plurality of DC-DC dimming devices 200 may be included, and different DC-DC dimming devices 200 may be the same or different, and may for example include a buck or boost DC-DC module, respectively.
In a preferred embodiment of the present invention, the light source 300 may include at least one group of LED light sources, for example, may include a plurality of groups of LED light sources. Each group of LED light sources corresponds to one DC-DC dimming device 200.
The surface light source circuit of the digital studio can realize transient highlight and non-stroboscopic light source control by adopting the DC power supply and the DC-DC dimming device with asynchronous rectification, so that the instantaneously highlighted LED light can be synchronously output when shooting is conducted in the shooting process of the digital studio.
Fig. 2 is a schematic block diagram of a second embodiment of the digital studio plane light source circuit of the present invention. As shown in fig. 2, the digital studio surface light source circuit of the present invention includes a DC power supply 100 for supplying a direct current, at least one DC-DC dimming device 200 for receiving the direct current and performing asynchronous rectification on the direct current, and at least one set of light sources 300 for receiving the asynchronous rectified direct current to emit light; the DC-DC dimming device 200 is electrically connected to the DC power source 100 and the light source 300, respectively.
Further, the DC power supply 100 may be a high resolution (or stepless) DC-DC adjustable constant current and voltage power supply using a buck (boost) mode. In another preferred embodiment of the invention, the DC power supply 100 may comprise an AC-DC converter for receiving an alternating mains current and converting the received alternating mains current into a direct current.
As shown in fig. 2, the DC-DC dimming device 200 may include a step-down DC-DC module 210 electrically connected to the DC power supply 100 to receive the direct current and perform step-down conversion on the direct current, and a first transient dimming control module 220 electrically connected to the step-down DC-DC module 210 to perform transient dimming control on the direct current after the step-down conversion; a boost DC-DC module 240 electrically connected to the DC power supply 100 for receiving the direct current and performing boost conversion on the direct current, and a second transient dimming control module 250 electrically connected to the boost DC-DC module 240 for performing transient dimming control on the direct current after the boost conversion. As will be appreciated by those skilled in the art, in a simplified embodiment of the present invention, the DC-DC dimming device 200 may further include a buck DC-DC module 210 and a first transient dimming control module 220, or only include a boost DC-DC module 240 and a second transient dimming control module 250. In a further preferred embodiment of the present invention, a plurality of DC-DC dimming devices 200 may be provided, one of which includes the step-down DC-DC module 210 and the first transient dimming control module 220, and the other of which includes the step-up DC-DC module 240 and the second transient dimming control module 250. Of course, in a further preferred embodiment of the present invention, a plurality of DC-DC dimming devices 200 may be provided, and each DC-DC dimming device 200 may include a step-down DC-DC module 210 and a first transient dimming control module 220, a step-up DC-DC module 240 and a second transient dimming control module 250.
In the preferred embodiment shown in fig. 2, the first transient dimming control module 220 includes: a first constant voltage transient dimming control unit 221 electrically connected to the step-down DC-DC module 210 and the light source 300, respectively, a first constant current transient dimming control unit 222 electrically connected to the step-down DC-DC module 210 and the light source 300, respectively, and a first RC integral feedback unit 223 electrically connected to the step-down DC-DC module 210 and the light source 300, respectively. The second transient dimming control module 250 includes: a second constant voltage transient dimming control unit 251 electrically connected to the step-up DC-DC module 240 and the light source 300, respectively, a second constant current transient dimming control unit 252 electrically connected to the step-up DC-DC module 240 and the light source 300, respectively, and a second RC integral feedback unit 253 electrically connected to the step-up DC-DC module 240 and the light source 300, respectively.
Those skilled in the art will appreciate that the buck DC-DC module 210 and the boost DC-DC module 240 may be constructed using any buck and boost chip known in the art. The first constant current transient dimming control unit 222 and the second constant current transient dimming control unit 252 may be constructed using any transient dimming control circuit known in the art. The first RC integrating feedback unit 223 and the second RC integrating feedback unit 253 can also be constructed using any RC integrating circuit known in the art.
In the preferred embodiment shown in fig. 2, the DC-DC dimming device 200 further comprises a boost overcurrent protection module 260 and/or a buck overcurrent protection module 230 connected to the boost DC-DC module 240 and/or the buck DC-DC module 210. It will be appreciated by those skilled in the art that the boost overcurrent protection module 260 and/or the buck overcurrent protection module 230 may be implemented using any overcurrent protection circuit known in the art.
In the preferred embodiment shown in FIG. 2, the light source 300 may include multiple sets of LED light sources 310 … 3N 0. Each group of LED light sources corresponds to one group of buck DC-DC module 210, first transient dimming control module 220, and buck overcurrent protection module 230 in the DC-DC dimming device 200, or corresponds to one group of boost DC-DC module 240, second transient dimming control module 250, and boost overcurrent protection module 260 in the DC-DC dimming device 200 according to actual needs thereof.
The surface light source circuit of the digital studio can realize transient highlight and non-stroboscopic light source control by adopting the DC power supply and the DC-DC dimming device with asynchronous rectification, so that the instantaneously highlighted LED light can be synchronously output when shooting is conducted in the shooting process of the digital studio.
Fig. 3 is a partial circuit schematic diagram of a third embodiment of the DC-DC dimming device of the digital studio surface light source circuit of the present invention. In the embodiment shown in fig. 3, the DC-DC dimming device preferably includes a buck DC-DC module 210, a first transient dimming control module 220, and a buck overcurrent protection module 230. The first transient dimming control module 220 includes: a first constant voltage transient dimming control unit 221 electrically connected to the step-down DC-DC module 210 and the light source 300, respectively, a first constant current transient dimming control unit 222 electrically connected to the step-down DC-DC module 210 and the light source 300, respectively, and a first RC integral feedback unit 223 electrically connected to the step-down DC-DC module 210 and the light source 300, respectively.
As shown in fig. 3, the buck DC-DC module 210 includes a buck DC-DC chip T1, a buck DC-DC chip T2, a MOS transistor Q1, and an inductor L1, wherein an input terminal of the buck DC-DC chip T1 is connected to the DC power supply 100, and an output terminal of the buck DC-DC chip T2 is connected to a first input terminal of the buck DC-DC chip. A first output terminal of the buck DC-DC chip T2 is connected to an input terminal of the first transient dimming control module 220. A second input terminal of the buck DC-DC chip T2 is connected to the feedback terminal of the first transient dimming control module 220, a second output terminal of the buck DC-DC chip T2 is connected to the gate of the MOS transistor Q1, the source of the MOS transistor Q1 is connected to the light source 300 through the inductor L1, and the drain is connected to the DC power supply 100. In the embodiment shown in fig. 3, an inductor C1 is further disposed between the DC power supply 100 and the ground, a diode DS1 is further disposed between the source of the MOS transistor Q1 and the ground, the anode of the diode DS1 is grounded, and the cathode is connected to the source of the MOS transistor Q1. The step-down DC-DC chip T2 may operate in a constant current or constant voltage mode and receive a control command from the memory OTP. Each control port of the voltage reduction DC-DC chip T2 can be externally connected with an overvoltage protection circuit, a short-circuit protection circuit, an over-temperature protection circuit and a switch signal circuit.
As further shown in fig. 3, the first constant-voltage transient dimming control unit 221 includes a diode DS2, a constant-voltage operational amplifier CV, a rectifier diode CS, a resistor R11, and a resistor R15, an anode of the diode DS2 is connected to the first input terminal of the step-down DC-DC chip T2, a cathode of the diode is connected to the output terminal of the constant-voltage operational amplifier CV, and a forward input terminal of the constant-voltage operational amplifier CV is connected to the forward input terminal of the constant-current operational amplifier CC of the first constant-current transient dimming control unit 222 and the cathode of the rectifier diode CS. The anode of the rectifier diode CS is grounded. The inverting input terminal of the constant voltage operational amplifier CV is connected to the ground through a resistor R11 and to the light source 300 through a resistor R15, respectively.
As further shown in fig. 3, the first constant-current transient dimming control unit 222 includes a diode DS3, a constant-current operational amplifier CC, a resistor R12, and a resistor R13, wherein an anode of the diode DS3 is connected to the first input terminal of the step-down DC-DC chip T2, and a cathode of the diode DS3 is connected to the output terminal of the constant-current operational amplifier CC. The reverse input end of the constant current operational amplifier CC is connected to the light source 300 through the resistor R12, and the forward input end thereof is connected to the first constant voltage transient dimming control unit 221 through the resistor R13.
As further shown in fig. 3, the first RC integrating feedback unit 223 includes inductors C2, C4, and C6, resistors R4, R5, R6, and R14. The boost overcurrent protection module 260 includes a feedback operational amplifier F1, resistors R8, and R10. The resistors R4, R5, R6 and R14 are connected in series between the ground and the PWM dimming control signal input end, the inductor C2 is connected between the connection point of the resistors R4 and R5 and the ground, the inductor C4 is connected between the connection point of the resistors R5 and R6 and the ground, and the inductor C6 is connected between the connection point of the resistors R6 and R14 and the ground. The output end of the feedback operational amplifier F1 is connected with the second input end of the voltage-reducing DC-DC chip T2, the positive input end is connected with the reference voltage through a resistor R8, and the negative input end is connected with the negative input end of the constant current operational amplifier CC through a resistor R10.
By adopting asynchronous rectification for high-power voltage reduction constant-current constant-voltage DC-DC drive, the phenomenon of circuit break of a synchronous rectification MOS is avoided, so that the direct current can be obtained by adopting conventional common-ground voltage reduction and increase with fast transient response and high stability, and ripple and stroboflash are also prevented. In this embodiment, the light source 300 is easily damaged by outputting a large current after the transient highlight is out of control or the DC power fails, and the boost overcurrent protection module 260 is specially designed to effectively protect the light source. When the detected voltage signal exceeds the set reference voltage, the comparator outputs high level to turn off the DC controller and turn off the whole digital studio surface light source circuit to protect the light source from being damaged,
fig. 4 is a partial circuit schematic diagram of a fourth embodiment of the DC-DC dimming device of the digital studio surface light source circuit of the present invention. Fig. 5 is a partial circuit schematic diagram of a fourth embodiment of the DC-DC dimming device of the digital studio surface light source circuit of the present invention. In the embodiment shown in fig. 4, the DC-DC dimming device preferably includes a boost DC-DC module 240, a second transient dimming control module 250, and a boost overcurrent protection module 260. The second transient dimming control module 250 includes: a second constant voltage transient dimming control unit 251 electrically connected to the step-up DC-DC module 240 and the light source 300, respectively, a second constant current transient dimming control unit 252 electrically connected to the step-up DC-DC module 240 and the light source 300, respectively, and a second RC integral feedback unit 253 electrically connected to the step-up DC-DC module 240 and the light source 300, respectively.
As shown in fig. 4, the boost DC-DC module 240 includes a buck DC-DC chip T3, a boost DC-DC chip T4, a MOS transistor Q2, an inductor L2, a MOS transistor Q4, a diode DS6, and a switch Q3, wherein an input terminal of the buck DC-DC chip T3 is connected to the DC power supply 100, and an output terminal thereof is connected to a first input terminal of the boost DC-DC chip T4. The gate of the MOS transistor Q2 is connected to the collector of the switching transistor Q3, the emitter of the switching transistor Q3 is grounded, and the source is connected to the feedback terminal of the second transient dimming control module 250. The drain of the MOS transistor Q2 is connected to the DC power supply 100, the source is connected to the anode of the diode DS6 through the inductor L2, the second input terminal of the boost DC-DC chip T4 is connected to the feedback terminal of the second transient dimming control module 250, the second output terminal of the boost DC-DC chip T4 is connected to the source and the gate of the MOS transistor Q4, the drain of the MOS transistor Q4 is connected to the anode of the diode DS6, and the cathode of the diode DS6 is connected to the light source 300.
In the embodiment shown in fig. 4, an inductor C7 is further disposed between the DC power supply 100 and ground, a capacitor C10 is disposed between the cathode of the diode DS6 and ground, and a resistor R19 is disposed between the source of the MOS transistor Q4 and ground. The source of the switching transistor Q3 and the feedback terminal of the second transient dimming control module 250 may further be provided with a resistor R17. The boost DC-DC chip T4 may operate in a constant current or constant voltage mode and receive a control command from the memory OTP. Each control port of the boosting DC-DC chip T4 can be externally connected with an overvoltage protection circuit, a short-circuit protection circuit, an over-temperature protection circuit and a switch signal circuit.
In the embodiment shown in fig. 4, the second constant voltage transient dimming control unit 251 includes a diode DS4, a constant voltage operational amplifier CV, a rectifier diode C11, a resistor R26 and a resistor R30, an anode of the diode DS4 is connected to the second input terminal of the boost DC-DC chip T4, a cathode of the diode DS4 is connected to the output terminal of the constant voltage operational amplifier CV, a forward input terminal of the constant voltage operational amplifier CV is connected to the forward input terminal of the constant current operational amplifier CC of the constant current transient dimming control unit and the cathode of the rectifier diode C11, and an anode of the rectifier diode C11 is grounded. The inverting input terminal of the constant voltage operational amplifier CV is connected to the ground through a resistor R26 and to the light source 300 through a resistor R30, respectively.
As further shown in fig. 4, the constant-current transient dimming control unit includes a diode DS5, a constant-current operational amplifier CC, a resistor R27, and a resistor R28, an anode of the diode DS5 is connected to the second input terminal of the boost DC-DC chip T4, a cathode of the diode DS5 is connected to the output terminal of the constant-current operational amplifier CC, a reverse input terminal of the constant-current operational amplifier CC is connected to the light source 300 through the resistor R27, and a forward input terminal of the constant-current operational amplifier CC is connected to the forward input terminal of the constant-voltage operational amplifier CV of the second constant-voltage transient dimming control unit 251 through the resistor R28.
As further shown in fig. 4, the second RC integrating feedback unit 253 includes inductors C8, C9, and C12, and resistors R18, R20, R21, and R29. The buck over-current protection module 230 comprises a feedback operational amplifier F2, resistors R23 and R25, wherein the resistors R18, R20, R21 and R29 are connected between the ground and the PWM dimming control signal input end in series, an inductor C8 is connected between the connection point of the resistors R18 and R20 and the ground, the inductor C9 is connected between the connection point of the resistors R20 and R21 and the ground, and the inductor C12 is connected between the connection point of the resistors R21 and R29 and the ground. The output end of the feedback operational amplifier F2 is connected with the second input end of the boosting DC-DC chip T4, the positive input end is connected with the reference voltage through a resistor R23, and the negative input end is connected with the negative input end of the constant current operational amplifier CC through a resistor R25.
By adopting asynchronous rectification for high-power voltage reduction constant-current constant-voltage DC-DC drive, the phenomenon of circuit break of a synchronous rectification MOS is avoided, so that the direct current can be obtained by adopting conventional common-ground voltage reduction and increase with fast transient response and high stability, and ripple and stroboflash are also prevented. In this embodiment, the light source 300 is easily damaged by outputting a large current after the transient highlight is out of control or the DC power fails, and the step-down overcurrent protection module 230 is specially designed to effectively protect the light source. When the detected voltage signal exceeds the set reference voltage, the comparator outputs high level to turn off the DC controller and turn off the whole digital studio surface light source circuit to protect the light source from being damaged,
the surface light source circuit of the digital studio can realize transient highlight and non-stroboscopic light source control by adopting the DC power supply and the DC-DC dimming device with asynchronous rectification, so that the instantaneously highlighted LED light can be synchronously output when shooting is conducted in the shooting process of the digital studio. By adopting asynchronous rectification for high-power voltage reduction constant-current constant-voltage DC-DC drive, the phenomenon of circuit break of a synchronous rectification MOS is avoided, so that the direct current can be obtained by adopting conventional common-ground voltage reduction and increase with fast transient response and high stability, and ripple and stroboflash are also prevented.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (6)
1. A digital shadow shed light source circuit, comprising: the LED lamp comprises a DC power supply for providing direct current, at least one DC-DC dimming device for receiving the direct current and performing asynchronous rectification on the direct current, and at least one group of light sources for receiving the direct current after the asynchronous rectification to emit light; the DC-DC dimming device is electrically connected with the DC power supply and the light source respectively; the DC-DC dimming device comprises a voltage reduction DC-DC module and a first transient dimming control module, wherein the voltage reduction DC-DC module is electrically connected with the DC power supply to receive the direct current and perform voltage reduction conversion on the direct current, and the first transient dimming control module is electrically connected with the voltage reduction DC-DC module to perform transient dimming control on the direct current after voltage reduction conversion;
the DC-DC dimming device comprises a boost DC-DC module electrically connected with the DC power supply to receive the direct current and perform boost conversion on the direct current, and a second transient dimming control module electrically connected with the boost DC-DC module to perform transient dimming control on the direct current after the boost conversion;
the first transient dimming control module comprises: the first constant-voltage transient dimming control unit is electrically connected with the step-down DC-DC module and the light source respectively, the first constant-current transient dimming control unit is electrically connected with the step-down DC-DC module and the light source respectively, and the first RC integral feedback unit is electrically connected with the step-down DC-DC module and the light source respectively;
the second transient dimming control module comprises: the second constant-voltage transient dimming control unit is electrically connected with the boost DC-DC module and the light source respectively, the second constant-current transient dimming control unit is electrically connected with the boost DC-DC module and the light source respectively, and the second RC integral feedback unit is electrically connected with the boost DC-DC module and the light source respectively.
2. The circuit of a surface light source of a digital studio according to claim 1, wherein the step-down DC-DC module comprises a first step-down DC-DC chip, a second step-down DC-DC chip, a first MOS transistor and a first inductor, the input end of the first step-down DC-DC chip is connected with the DC power supply, the output end of the first step-down DC-DC chip is connected with the first input end of the second step-down DC-DC chip, the first output end of the second buck DC-DC chip is connected with the input end of the first transient dimming control module, the second input end of the second buck DC-DC chip is connected with the feedback end of the first transient dimming control module, the second output end of the second step-down DC-DC chip is connected with the grid electrode of the first MOS tube, the source electrode of the first MOS tube is connected with the light source through the first inductor, and the drain electrode of the first MOS tube is connected with the DC power supply.
3. The planar light source circuit of claim 2, wherein the first constant voltage transient dimming control unit comprises a first diode, a first constant voltage operational amplifier, a first rectifying diode, a first resistor and a second resistor, wherein an anode of the first diode is connected to the first input terminal of the second buck DC-DC chip, and a cathode of the first diode is connected to the output terminal of the first constant voltage operational amplifier, a forward input terminal of the first constant voltage operational amplifier is connected to the first constant current transient dimming control unit and the cathode of the first rectifying diode, an anode of the first rectifying diode is grounded, and a reverse input terminal of the first constant voltage operational amplifier is grounded via the first resistor and connected to the light source via the second resistor; the first constant-current transient dimming control unit comprises a second diode, a first constant-current operational amplifier, a third resistor and a fourth resistor, wherein the anode of the second diode is connected with the first input end of the second buck DC-DC chip, the cathode of the second diode is connected with the output end of the first constant-current operational amplifier, the reverse input end of the first constant-current operational amplifier is connected with the light source through the third resistor, and the forward input end of the first constant-current operational amplifier is connected with the first constant-voltage transient dimming control unit through the fourth resistor.
4. The planar light source circuit for digital studio of claim 1, wherein the boost DC-DC module comprises a third buck DC-DC chip, a boost DC-DC chip, a second MOS transistor, a second inductor, a third MOS transistor, a third diode, and a switch transistor, wherein the input terminal of the third buck DC-DC chip is connected to the DC power supply, the output terminal thereof is connected to the first input terminal of the boost DC-DC chip, the gate of the second MOS transistor is connected to the collector of the switch transistor, the emitter of the switch transistor is grounded, the source thereof is connected to the feedback terminal of the second transient dimming control module, the drain of the second MOS transistor is connected to the DC power supply, the source thereof is connected to the anode of the third diode via the second inductor, the second input terminal of the boost DC-DC chip is connected to the feedback terminal of the second transient dimming control module, the second output end of the boosting DC-DC chip is connected with the source electrode and the grid electrode of the third MOS tube, the drain electrode of the third MOS tube is connected with the anode of the third diode, and the cathode of the third diode is connected with the light source.
5. The planar light source circuit of claim 4, wherein the second constant voltage transient dimming control unit comprises a fourth diode, a second constant voltage operational amplifier, a third rectifying diode, a fifth resistor and a sixth resistor, wherein an anode of the fourth diode is connected to the second input terminal of the boost DC-DC chip, and a cathode of the fourth diode is connected to the output terminal of the second constant voltage operational amplifier, a forward input terminal of the second constant voltage operational amplifier is connected to the cathodes of the constant current transient dimming control unit and the third rectifying diode, an anode of the third rectifying diode is grounded, and a reverse input terminal of the second constant voltage operational amplifier is grounded via the fifth resistor and connected to the light source via the sixth resistor, respectively; the constant-current transient dimming control unit comprises a fifth diode, a second constant-current operational amplifier, a seventh resistor and an eighth resistor, wherein the anode of the fifth diode is connected with the second input end of the boosting DC-DC chip, the cathode of the fifth diode is connected with the output end of the second constant-current operational amplifier, the reverse input end of the second constant-current operational amplifier is connected with the light source through the seventh resistor, and the forward input end of the second constant-current operational amplifier is connected with the second constant-voltage transient dimming control unit through the eighth resistor.
6. The circuit of claim 1, wherein the DC-DC dimming device further comprises a boost overcurrent protection module and/or a buck overcurrent protection module connected to the boost DC-DC module and/or the buck DC-DC module.
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| CN101355840A (en) * | 2007-07-24 | 2009-01-28 | 通嘉科技股份有限公司 | Light emitting assembly driving circuit |
| CN202721869U (en) * | 2012-07-30 | 2013-02-06 | 西北工业大学 | An Embedded Intelligent Constant Current Driver |
| CN107006107A (en) * | 2014-12-12 | 2017-08-01 | 罗姆股份有限公司 | Lighting device |
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| US9429965B2 (en) * | 2009-11-03 | 2016-08-30 | Advanced Analogic Technologies Incorporated | Multiple chip voltage feedback technique for driving LED's |
| US9684326B2 (en) * | 2013-02-01 | 2017-06-20 | Alpha And Omega Semiconductor Incorporated | Method and circuit for detecting short circuit in an asynchronous DC-DC boost converter |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101355840A (en) * | 2007-07-24 | 2009-01-28 | 通嘉科技股份有限公司 | Light emitting assembly driving circuit |
| CN202721869U (en) * | 2012-07-30 | 2013-02-06 | 西北工业大学 | An Embedded Intelligent Constant Current Driver |
| CN107006107A (en) * | 2014-12-12 | 2017-08-01 | 罗姆股份有限公司 | Lighting device |
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