CN212851136U - Power supply and light source system - Google Patents
Power supply and light source system Download PDFInfo
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- CN212851136U CN212851136U CN202021077984.0U CN202021077984U CN212851136U CN 212851136 U CN212851136 U CN 212851136U CN 202021077984 U CN202021077984 U CN 202021077984U CN 212851136 U CN212851136 U CN 212851136U
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Abstract
The application discloses a power supply and a light source system, wherein the power supply comprises a control circuit and at least one constant current circuit, and the control circuit is used for generating a control signal according to a current instruction; the voltage reduction circuit in the constant current circuit is used for receiving a power supply signal and a control signal and converting the power supply signal into a constant current signal according to the control signal; the average current detection circuit is used for detecting the average current of the signal input to the constant current circuit and generating a voltage feedback signal; the peak current detection circuit is used for detecting the peak current of the signal output by the constant current circuit; the feedback compensation circuit is used for receiving the voltage feedback signal and compensating the signal input to the control circuit according to the voltage feedback signal, so that the control circuit dynamically adjusts the magnitude of the current signal output by the voltage reduction circuit according to the voltage feedback signal and the peak current. Through the mode, the output current can be dynamically adjusted, and the control circuit is simplified.
Description
Technical Field
The application relates to the technical field of circuits, in particular to a power supply and a light source system.
Background
With the rapid development of LED (Light Emitting Diode) and laser technology, LEDs and lasers are widely used in many fields; at present, a multi-output chip adopts a low-current LED, the corresponding chip is generally a built-in current detection and driving switching tube, the power consumption and the energy are both small, and the multi-output chip is not suitable for an application scene with large current; for a light source used for a laser projector, the driving current ratio is large, the existing driving mode connects lasers in series and then drives the lasers, so that each laser is inconvenient to adjust independently, and if each laser is provided with one driving, the volume and the cost of a driving circuit are high, so that the driving circuit is not suitable for a Local Dimming laser projector; the problem that independent adjustment cannot be carried out is solved by adopting a multi-channel linear constant current mode, but the analog quantity of each path of current is uniformly adjusted, so that the Local Dimming is inconvenient to be respectively adjusted, and the usability in the Local Dimming is not high.
Disclosure of Invention
The application provides a power supply and a light source system, which can dynamically adjust output current and simplify a control circuit.
In order to solve the technical problem, the technical scheme adopted by the application is as follows: providing a power supply, the power supply comprising: the control circuit is used for receiving a current instruction and generating a control signal according to the current instruction, wherein the current instruction comprises at least one current value; the constant current circuit includes: the device comprises a voltage reduction circuit, an average current detection circuit, a peak current detection circuit and a feedback compensation circuit; the voltage reduction circuit is used for receiving the power supply signal and the control signal and converting the power supply signal into a constant current signal according to the control signal; the average current detection circuit is connected with the voltage reduction circuit and used for detecting the average current of the signal input to the constant current circuit and generating a voltage feedback signal; the peak current detection circuit is connected with the voltage reduction circuit and is used for detecting the peak current of the signal output by the constant current circuit; the feedback compensation circuit is connected with the average current detection circuit and used for receiving the voltage feedback signal and compensating the signal input to the control circuit according to the voltage feedback signal, so that the control circuit dynamically adjusts the magnitude of the current signal output by the voltage reduction circuit according to the voltage feedback signal and the peak current; the current value in the current command is the same as the current value of the constant current signal output by the voltage reduction circuit.
In order to solve the above technical problem, another technical solution adopted by the present application is: there is provided a light source system comprising: the processing circuit is used for receiving the image signals, processing the image signals to obtain corresponding current values, and generating current instructions according to the current values; the power supply is connected with the processing circuit and used for receiving the current instruction and outputting a constant current value corresponding to the current instruction; the light source is connected with the power supply and used for receiving the current value output by the power supply and emitting light with corresponding brightness; wherein, the power supply is the power supply.
Through the scheme, the beneficial effects of the application are that: the power supply in this application includes constant current circuit and control circuit, and this constant current circuit includes: the device comprises a voltage reduction circuit, an average current detection circuit, a peak current detection circuit and a feedback compensation circuit; the voltage reduction circuit can receive the power supply signal and the control signal generated by the control circuit and convert the power supply signal into a constant current signal; the average current detection circuit can output a voltage feedback signal and input the voltage feedback signal to the control circuit through the feedback compensation circuit; the feedback compensation circuit can compensate the signal input to the control circuit according to the voltage feedback signal, the control circuit can judge whether the current value output by the constant current circuit is the same as the corresponding current value in the current instruction or not through the voltage feedback signal, and if not, the control circuit can dynamically adjust the current output by the constant current circuit by controlling the voltage reduction circuit; in addition, the peak current detection circuit can be used for detecting whether the peak current of the signal output by the constant current circuit meets the requirement or not and feeding back the peak current to the control circuit, so that the control circuit can dynamically adjust the size of the output signal; when the power supply is applied to a light source system, one constant current circuit can simultaneously control a plurality of constant current circuits, so that the light source is driven by the constant current circuits, the control circuit can be simplified, the integration level of the control circuit is improved, the circuit size is reduced, and the cost is saved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. Wherein:
FIG. 1 is a schematic diagram of an embodiment of a power supply provided herein;
FIG. 2 is a schematic diagram of another embodiment of a power supply provided herein;
FIG. 3 is a schematic diagram of the control circuit, the first amplifying circuit and the feedback compensation circuit in the embodiment shown in FIG. 2;
FIG. 4 is a schematic diagram of the driving circuit in the embodiment shown in FIG. 2;
FIG. 5 is a schematic structural diagram of an embodiment of a light source system provided in the present application;
FIG. 6 is a schematic structural diagram of another embodiment of a light source system provided herein;
FIG. 7 is a schematic structural diagram of a light emitting assembly in the embodiment shown in FIG. 6;
fig. 8 is another arrangement of the light source system in the embodiment shown in fig. 6.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
According to the continuous innovation breakthrough of the current projection technology and the lower and lower realization cost, especially the gradual popularization of the laser projector, part of the large-screen traditional television used for families is slowly replaced by the laser projector, however, the matched driving power supply and the chip scheme are in a lagging state, so that the application requirements are met by combining the traditional chip and adding a proper conversion circuit design.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an embodiment of a power supply provided in the present application, and a power supply 10 includes: a control circuit 11 and at least one constant current circuit 12.
The control circuit 11 is configured to receive a current command and generate a control signal according to the current command, and specifically, the control circuit 11 may be an MCU (micro controller Unit), and the current command includes at least one current value.
The constant current circuit 12 is connected to the control circuit 11, the constant current circuit 12 includes a voltage step-down circuit 121, an average current detection circuit 122, a peak current detection circuit 123, and a feedback compensation circuit 124, which are connected to each other, the constant current circuit 12 can output a plurality of constant current values each corresponding to a current value in a current command under the control of the control circuit 11, for example, the power source 10 is connected to one light emitting element, the light emitting assembly comprises a red light source, a green light source and a blue light source, wherein the light source can be an LED or a laser, at least one current value in the current command comprises three current values I1-I3, the control circuit 11 can output a constant current value I1 to the red light source after receiving the current command, then outputting a constant current value I2 to the green light source, and finally outputting a constant current value I3 to the blue light source, so that the light-emitting component emits light with corresponding brightness; or the current values I1-I3 can be output to the red light source, the green light source and the blue light source respectively at the same time, and the magnitudes of the current values I1-I3 can be adjusted respectively.
The voltage reduction circuit 121 is configured to receive a power supply signal and a control signal, and convert the power supply signal into a constant current signal according to the control signal; specifically, the current value in the current command is the same as the current value of the constant current signal output by the voltage-reducing circuit 121, the power supply signal is a dc signal, such as 12V, and the voltage-reducing circuit 121 may be a BUCK circuit, and can process the input power supply signal and output a current signal.
The average current detection circuit 122 is connected to the step-down circuit 121, and the average current detection circuit 122 detects an average current of a signal input to the constant current circuit 12, generates a voltage feedback signal, and inputs the voltage feedback signal to the feedback compensation circuit 124.
The peak current detection circuit 123 is connected to the voltage reduction circuit 121, and is configured to detect a peak current of a signal output from the constant current circuit 12, and can accurately detect the peak current cycle by cycle so as to prevent erroneous detection or malfunction.
The feedback compensation circuit 124 is connected to the average current detection circuit 122, and is configured to receive the voltage feedback signal and compensate the signal input to the control circuit 11 according to the voltage feedback signal, so that the control circuit 11 can dynamically adjust the magnitude of the current signal output by the voltage reduction circuit 121 according to the voltage feedback signal and the peak current. Specifically, the control circuit 11 may receive the voltage feedback signal through the feedback compensation circuit 124, and after receiving the voltage feedback signal, control the voltage reduction circuit 121 to dynamically adjust the magnitude of the current signal output by the voltage reduction circuit 121.
In the embodiment, the average current detection circuit 122 is used to generate a voltage feedback signal, and the voltage feedback signal is input to the feedback compensation circuit 124, the feedback compensation circuit 124 can compensate the signal input to the control circuit 11 according to the voltage feedback signal, so that the control circuit 11 can determine whether the current value output by the constant current circuit 12 is the same as the corresponding current value in the current command according to the voltage feedback signal, if not, the control circuit 11 dynamically adjusts the current output by the constant current circuit 12 by controlling the voltage reduction circuit 121, so that the constant current circuit 12 outputs a constant current value that is the same as the corresponding current value in the current command, and can detect whether the peak value of the output current is appropriate by the peak current detection circuit 123 and feed back the peak value to the control circuit 11 for real-time adjustment, and the magnitude of the output current of the constant current circuit 12 is not limited by the control circuit 11, the method can be applied to the application scene of large current.
Referring to fig. 2 to 4, fig. 2 is a schematic structural diagram of another embodiment of a power supply provided in the present application, fig. 3 is a schematic structural diagram of a control circuit, a first amplifying circuit and a feedback compensation circuit, fig. 4 is a schematic structural diagram of a driving circuit, in this embodiment, a power supply 10 further includes a fuse 13 and a common mode coil 14, and a constant current circuit further includes: a driving circuit 125, a first amplifying circuit 126, a second amplifying circuit 127, and an overvoltage protection circuit 128.
In order to prevent the circuit from short-circuiting due to excessive current or voltage, a fuse 13 is provided, one end of the fuse 13 is used for receiving a power supply signal, the other end of the fuse 13 is connected with the average current detection circuit 122, and when the amplitude of the power supply signal is greater than a second preset voltage value, the fuse 13 can prevent the power supply signal from flowing into the voltage reduction circuit 121; specifically, the second preset voltage value is a safe voltage of the voltage-reducing circuit 121, and when the voltage of the power supply signal is greater than the second preset voltage value, the fuse 13 cuts off a path with the voltage-reducing circuit 121, so that the power supply signal cannot flow into the voltage-reducing circuit 121.
The voltage-reducing circuit 121 includes: the power supply circuit comprises a storage capacitor C1, an inductor L, a diode D1 and a first switching tube T1, wherein one end of the storage capacitor C1 is used for receiving a power supply signal transmitted through a fuse 13, the other end of the storage capacitor C1 is connected with one end of the inductor L, the storage capacitor C1 can comprise a plurality of capacitors connected in parallel, and the other end of the inductor L is connected with a first end of the first switching tube T1; one end of a diode D1 is connected with one end of a storage capacitor C1, and the other end of a diode D1 is connected with the other end of an inductor L; the second end of the first switch tube T1 is connected to the driving circuit 125, and the third end of the first switch tube T1 is grounded; specifically, the first switch transistor T1 is an N-type Metal Oxide Semiconductor (nmos), and the first end, the second end, and the third end are a drain, a gate, and a source, respectively.
The common mode coil 14 is used for filtering interference signals, a first end of the common mode coil 14 is connected to the average current detection circuit 122, a second end of the common mode coil 14 is connected to the other end of the storage capacitor C1, a third end of the common mode coil 14 serves as a positive electrode LD + of the power supply 10 and outputs a constant current signal, and a fourth end of the common mode coil 14 serves as a negative electrode LD-of the power supply 10.
In a specific embodiment, as shown in fig. 2, the average current detection circuit 122 includes a first resistor R1 and a differential operational amplifier circuit 1221 connected to each other, the differential operational amplifier circuit 1221 is connected to the first resistor R1, and is configured to receive the first differential signal and the second differential signal at two sides of the first resistor R1 and output the differential amplified signal to the feedback compensation circuit 124; one end of the first resistor R1 is connected to the other end of the fuse 13, the other end of the first resistor R1 is connected to the first end of the common mode coil 14, and the first resistor R1 is connectable to the control circuit 11, so that the average current detection can be realized by detecting the current flowing into the first resistor R1.
The peak current detection circuit 123 includes a second resistor R2, a third resistor R3 and a capacitor C2, one end of the second resistor R2 is connected to the third end of the first switch transistor T1, the other end of the second resistor R2 is grounded, and the second resistor R2 is connectable to the control circuit 11; one end of the third resistor R3 is connected with one end of the second resistor R2, and the other end of the third resistor R3 is connected with the overvoltage protection circuit 128; one end of the capacitor C2 is connected with one end of the third resistor R3, and the other end of the capacitor C2 is grounded; peak current detection may be achieved by detecting the current flowing through the second resistor R2.
With reference to fig. 2 and fig. 3, the constant current circuit further includes a first amplifying circuit 126 and a second amplifying circuit 127, the first amplifying circuit 126 is connected to the average current detecting circuit 122, and is configured to amplify the voltage feedback signal and input the amplified signal to the feedback compensating circuit 124; the second amplification circuit 127 is connected to the peak current detection circuit 123, and amplifies the peak current, and inputs the amplified signal to the current comparator 111 in the control circuit 11.
Further, the peak current may be amplified by the second amplifying circuit 127 and then input to the control circuit 11, and when the peak current is too large or the second resistor R2 is open, the peak current will enter an overvoltage protection point through the diode D2, and the first switching tube T1 is turned off for protection; specifically, when the peak current is too large, the voltage at the point a is also large, the peak current is sent to the first pin of the control circuit 11 through the diode D2 for detection, when the control circuit 11 detects that the voltage is too large, the output of a PWM (Pulse Width Modulation) signal is stopped, and the first switching tube T1 is turned off, so that protection is realized.
The driving circuit 125 is connected to the control circuit 11 and the voltage-decreasing circuit 121, and is configured to provide a driving signal to the voltage-decreasing circuit 121 so as to operate the voltage-decreasing circuit 121; specifically, with reference to fig. 2 and 4, the driving circuit 125 includes a driving chip 1251 and a peripheral circuit, the peripheral circuit is used for supplying power to the driving chip 1251, limiting the magnitude of a signal input to the driving chip 1251 or limiting the magnitude of a signal input to the first switching tube T1, and includes a fourth resistor R4 to an eighth resistor R8 and a capacitor C3, one end of the fourth resistor R4 receives a power supply signal, the other end of the fourth resistor R4 is connected to one end of a capacitor C3 and a power supply terminal VDD of the driving chip 1251, and the other end of the capacitor C3 is grounded; one end of the fifth resistor R5 is connected to the control circuit 11, the other end of the fifth resistor R5 is connected to one end of the sixth resistor R6 and the signal input end Vin of the driving chip 1251, the other end of the sixth resistor R6 is connected to the ground GND of the driving chip 1251 and is grounded, one end of the seventh resistor R7 is connected to the signal output end Vout of the driving chip 1251, the other end of the seventh resistor R7 is connected to one end of the eighth resistor R8 and the second end of the first switch tube T1, and the other end of the eighth resistor R8 is grounded.
As shown in fig. 3, the control circuit 11 includes an operational amplifier 112, the feedback compensation circuit 124 includes a feedback circuit 1241 and a compensation circuit 1242 connected to each other, the feedback circuit 1241 is configured to receive a voltage feedback signal and input the voltage feedback signal to an inverting input terminal of the operational amplifier 112; the feedback circuit 1241 is configured to receive a signal output by the operational amplifier 112 to compensate a signal input to the inverting input terminal of the operational amplifier 112, and the compensation circuit 1242 is connected between the second pin of the control circuit 11 and the third pin of the control circuit 11, and configured to control a zero and a pole fed back by the operational amplifier 112.
The differential operational amplifier circuit 1221 includes a differential operational amplifier chip 12211, after the average current signal is amplified by the differential operational amplifier chip 12211, a voltage is generated across a ninth resistor R9, and the voltage passes through the first amplifier circuit 126 and then enters the feedback compensation circuit 124, and then enters the operational amplifier 112 through a third pin of the control circuit 11 for comparison, so as to change the current amplitude; specifically, one image needs three colors of red, green and blue to be combined, and one constant current circuit can drive light emitting elements of the three colors of red, green and blue in a time-sharing manner corresponding to 3 current values, so that the output current values can be controlled in a segmented manner according to the red, green and blue.
As shown in fig. 2, the power supply 10 further includes an overvoltage protection circuit 128, and the overvoltage protection circuit 128 is connected to the voltage reduction circuit 121, and is configured to convert the dynamic voltages of the positive electrode of the power supply 10 and the negative electrode of the power supply 10 into static voltages, and feed back the static voltages to the control circuit 11, so that the control circuit 11 stops outputting the pulse width modulation signal after detecting that the voltage output by the constant current circuit is greater than the preset voltage threshold; specifically, the tenth resistor R10 and the eleventh resistor R11 convert the voltage difference between the positive electrode and the negative electrode of the floating power supply 10 into a static voltage across the twelfth resistor R12 through the transistor Q and the twelfth resistor R12, and the static voltage is transmitted to the first pin of the control circuit 11 through the thirteenth resistor R13, so that the control circuit 11 performs an overvoltage protection operation.
The control circuit 11 is further configured to compare the voltage feedback signal with a first preset voltage value after receiving the voltage feedback signal output by the first amplifying circuit 126, and output a control signal to the driving circuit 125 according to the comparison result, so as to adjust the duty ratio of the first switching tube T1.
In a specific embodiment, as shown in fig. 3, the control circuit 11 further includes: a voltage comparator 113, a digital-to-analog converter 114, a slope compensator 115, a complementary output generator 116, a pulse width modulation circuit 117, and a digital signal modulator 118.
The voltage comparator 113 is connected to the constant current circuit, and is configured to compare a voltage output by the constant current circuit with a preset voltage threshold, and output a first voltage comparison result; specifically, the non-inverting input terminal of the voltage comparator 113 may receive a predetermined voltage threshold, where the predetermined voltage threshold may be a voltage output by a Digital to Analog Converter (DAC), the inverting input terminal of the voltage comparator 113 is connected to the constant current circuit, and outputs a high level to the complementary output generator 116 when the voltage output by the constant current circuit is greater than the predetermined voltage threshold, and outputs a low level to the complementary output generator 116 when the voltage output by the constant current circuit is less than or equal to the predetermined voltage threshold.
The digital-to-analog converter 114 is configured to perform digital-to-analog conversion on a corresponding current value in the current instruction to obtain an analog voltage, where the voltage output by the digital-to-analog converter 114 is not fixed and changes with the brightness of each frame of picture.
The operational amplifier 112 is connected to the digital-to-analog converter 114, and is configured to receive the analog voltage output by the digital-to-analog converter 114, and compare the analog voltage with a fed-back average voltage to obtain a second voltage comparison result, where the fed-back average voltage corresponds to the average current; specifically, the non-inverting input terminal of the operational amplifier 112 is connected to the digital-to-analog converter 114, and the inverting input terminal of the operational amplifier 112 is connected to the feedback compensation circuit 124.
The slope compensator 115 is connected to the operational amplifier 112, and is used for correcting the signal output by the operational amplifier 112; the current comparator 111 is connected to the slope compensator 115, and is configured to receive the peak current, compare the peak current with a preset current threshold, and output a current comparison result; specifically, the inverting input terminal of the current comparator 111 is connected to the slope compensator 115, and the non-inverting input terminal of the current comparator 111 can receive the peak current fed back by the peak current detection circuit 123, and output a high level to the complementary output generator 116 when the peak current is greater than the preset current threshold, and output a low level to the complementary output generator 116 when the peak current is less than or equal to the preset current threshold.
The pulse width modulation circuit 117 is connected to the complementary output generator 116, and is configured to generate a pulse signal, which may be a high frequency pulse signal, and output the pulse signal to the complementary output generator 116.
The digital signal modulator 118 is connected to the complementary output generator 116, and is configured to output the digital modulation signal to the complementary output generator 116, so that the complementary output generator 116 adjusts the output pulse width modulation signal according to the digital modulation signal, the pulse signal and the signal output by the current comparator 111.
The configurable logic unit 119 is connected to the digital signal modulator 118, and is configured to process the input enable signal to control the complementary output generator 116 through the digital signal modulator 118; specifically, as shown in fig. 3, the enable signals include a RED enable signal RED _ EN, a green enable signal GRE _ EN, and a blue enable signal BLU _ EN, and the RED enable signal RED _ EN, the green enable signal GRE _ EN, and the blue enable signal BLU _ EN generate a low-frequency envelope by performing an or logic through the configurable logic unit 119, and the complementary output generator 116 is compositely controlled by the digital signal modulator 118, so that the overshoot and ramp-up problems during switching are optimized, and the optimization can be performed by program control according to an actual application scenario.
The complementary output generator 116 is connected to the current comparator 111, the voltage comparator 113, and the pulse width modulation circuit 117, and is configured to adjust a duty ratio of the output pulse width modulation signal according to the second voltage comparison result fed back by the operational amplifier 112; specifically, the signal output by the feedback compensation circuit 124 is sent to the operational amplifier 112, the operational amplifier 112 compares the signal with the signal output by the digital-to-analog converter 114, and outputs the second voltage comparison result to the slope compensator 115, since the slope compensator 115 is connected to the inverting input terminal of the current comparator 111, the output of the current comparator 111 changes, and the current comparator 111 outputs the signal to the complementary output generator 116, thereby adjusting the duty ratio of the signal output by the complementary output generator 116.
The complementary output generator 116 is further configured to receive the first voltage comparison result/current comparison result, and determine whether to stop outputting the pwm signal according to the first voltage comparison result/current comparison result; specifically, the complementary output generator 116 is configured to stop outputting the pulse width modulation signal to the constant current circuit when the voltage output by the constant current circuit is greater than the preset voltage threshold; or when the peak current is larger than the preset current threshold, stopping outputting the pulse width modulation signal to the constant current circuit.
The power supply 10 may be connected to a load, which may be an LED or a laser, to drive the load to operate; specifically, when the power supply 10 is connected to a load, and the driving circuit 125 drives the first switching tube T1 to be turned on, the power supply signal sequentially passes through the first resistor R1 and the common mode coil 14, is input to the load from the third end of the common mode coil 14, flows into the inductor L through the load, and then flows into the ground through the first switching tube T1 and the second resistor R2, so as to complete energy storage, and the load enters a working state; when the first switch transistor T1 is turned off, the inductor L charges the storage capacitor C1 through the diode D1, and the load is not operated.
In this embodiment, the constant current circuit can complete the conversion and protection of power energy, the control circuit 11 can configure control logic through software according to the topology structure of the constant current circuit, and can receive a control instruction in real time by using a communication circuit connected with the control logic, and turn on output, turn off output or adjust an output current value at any time; when the amplitude of the output current is adjusted in a fast sectional manner, a control mode that an external detection and control circuit is combined with an internal micro-circuit of the control circuit 11 is adopted; when the circuit is in an overcurrent or open circuit, the diode D2 is used for protection, and the pin can be shared with the overvoltage protection circuit 128, so that the pin occupation amount of the control circuit 11 is reduced.
Referring to fig. 5, fig. 5 is a schematic structural diagram of an embodiment of a light source system provided in the present application, the light source system including: a power supply 10, a processing circuit 20 and a light source 30.
The processing circuit 20 is configured to receive an image signal, process the image signal to obtain a corresponding current value, and generate a current instruction according to the current value; specifically, the image signal may be a digital image signal, and the processing circuit 20 may be an FPGA (Field Programmable Gate Array).
Further, the processing circuit 20 is configured to analyze the image signal to obtain a brightness value corresponding to each pixel in the image, convert the brightness value into a current value, and issue a current instruction through a Serial Peripheral Interface (SPI); specifically, for a color image, the luminance value corresponding to each pixel includes a red luminance value, a green luminance value, and a blue luminance value.
The power supply 10 is connected to the processing circuit 20, and is configured to receive a current instruction issued by the processing circuit 20 and output a constant current value corresponding to the current instruction, where the power supply 10 is the power supply 10 in the foregoing embodiment; specifically, the power supply 10 includes at least one control circuit 11 and at least one constant current circuit 12, the control circuit 11 is configured to adjust an output signal after receiving a current instruction and a frame synchronization signal, so that a current value received by the Light source 30 matches a brightness value of an image, the control circuit 11 may be a Digital control chip, the frame synchronization signal may be a signal output by a Digital Light Processing (DLP) chip or a video signal chip, and the Digital control chip, after receiving the current instruction, rapidly changes the output current value when the frame synchronization signal appears, so as to achieve rapid change of currents of three colors, namely red, green, and blue; the amplitude of the current output by each constant current circuit 12 can be dynamically adjusted between 0.5 and 5A, and when the current value of each constant current circuit 12 is rapidly refreshed, the refreshing rate can reach 120 Hz.
The light source 30 is connected to the power source 10, and is configured to receive a current value output by the power source 10 and emit light with a corresponding brightness.
In a specific embodiment, referring to fig. 5 and fig. 6, the light source 30 includes a plurality of light emitting elements 31 arranged in an array, each light emitting element 31 includes a red light emitting element 311, a green light emitting element 312, and a blue light emitting element 313, and the light emitting elements (including the red light emitting element 311, the green light emitting element 312, or the blue light emitting element 313) may be LEDs or lasers; for example, each power supply 10 includes two control circuits 11, each control circuit 11 can control 4 constant current circuits 12, and since each light emitting element 31 includes 3 light emitting elements, each constant current circuit 12 can alternately drive 3 light emitting elements, and thus 24 light emitting elements can be driven to operate.
As shown in fig. 7, the cathodes of the red light emitting device 311, the green light emitting device 312, and the blue light emitting device 313 are all connected to the cathode LD-of the power supply 10, the anodes of the red light emitting device 311, the green light emitting device 312, and the blue light emitting device 313 are respectively connected to the anode LD + of the power supply 10 through the second switching tubes T21-T23, the control ends of the second switching tubes are connected to the control circuit 11, and the control circuit 11 is configured to output an enable signal to the control ends of the second switching tubes, so that the second switching tubes T21-T23 corresponding to the red light emitting device 311, the green light emitting device 312, and the blue light emitting device 313 are turned on in turn, thereby achieving alternate light emission.
Further, the control circuit 11 generates a RED light enable signal RED _ EN, a green light enable signal GRE _ EN, and a blue light enable signal BLU _ EN, respectively, when the RED light enable signal RED _ EN is at a high level, and the green light enable signal GRE _ EN and the blue light enable signal BLU _ EN are at a low level, the second switch tube T21 corresponding to the RED light emitting element 311 is turned on, and the constant current circuit 12 outputs a signal to the RED light emitting element 311 through the second switch tube T21, so that the RED light emitting element 311 emits RED light; when the green enable signal GRE _ EN is at a high level, and the RED enable signal RED _ EN and the blue enable signal BLU _ EN are both at a low level, the second switch tube T22 corresponding to the green light emitting element 312 is turned on, and the constant current circuit 12 sends a signal to the green light emitting element 312 through the second switch tube T22, so that the green light emitting element 312 emits green light; when the blue enable signal BLU _ EN is at a high level and the RED enable signal RED _ EN and the green enable signal GRE _ EN are both at a low level, the second switch tube T23 corresponding to the blue light emitting element 313 is turned on, and the constant current circuit 12 sends a signal to the blue light emitting element 313 through the second switch tube T23, so that the blue light emitting element 313 emits blue light.
In order to avoid the mutual interference between the power supply line (i.e., the power channel) and the output line (i.e., the control channel) of the constant current circuit 12, and to make the control channel and the power channel staggered, as shown in fig. 8, the processing circuit 20 may be disposed at an upper middle position of the circuit board, the processing circuit 20 is respectively in communication with the two control circuits 11, the power supply interface 40 is disposed at a lower middle position of the circuit board, and the power supply interface 40 is used for receiving a power supply signal.
The embodiment provides a scheme suitable for local dimming of a projector, wherein a digital control chip is adopted to control four constant current circuits 12, each constant current circuit 12 can drive a red light emitting element 311, a green light emitting element 312 and a blue light emitting element 313 in a time-sharing manner by combining a frame synchronization signal, the control is accurate, and the local dimming of the projector can be realized after a plurality of circuits are cascaded; because a plurality of constant current circuits 12 can share one digital control chip, the number of the digital control chips can be effectively reduced, the simplification of a control circuit is facilitated, the circuit size can be reduced, and the cost is saved.
The above embodiments are merely examples, and not intended to limit the scope of the present application, and all modifications, equivalents, and flow charts using the contents of the specification and drawings of the present application, or those directly or indirectly applied to other related arts, are included in the scope of the present application.
Claims (10)
1. A power supply, comprising:
the control circuit is used for receiving a current instruction and generating a control signal according to the current instruction, wherein the current instruction comprises at least one current value;
at least one constant current circuit connected to the control circuit, each of the constant current circuits including:
the voltage reduction circuit is used for receiving a power supply signal and the control signal and converting the power supply signal into a constant current signal according to the control signal;
the average current detection circuit is connected with the voltage reduction circuit and is used for detecting the average current of the signal input to the constant current circuit and generating a voltage feedback signal;
the peak current detection circuit is connected with the voltage reduction circuit and is used for detecting the peak current of the signal output by the constant current circuit;
the feedback compensation circuit is connected with the average current detection circuit and used for receiving the voltage feedback signal and compensating the signal input to the control circuit according to the voltage feedback signal, so that the control circuit dynamically adjusts the magnitude of the current signal output by the voltage reduction circuit according to the voltage feedback signal and the peak current;
wherein a current value in the current command is the same as a current value of the constant current signal output by the voltage-reducing circuit.
2. The power supply of claim 1, wherein the control circuit comprises:
the voltage comparator is connected with the constant current circuit and used for comparing the voltage output by the constant current circuit with a preset voltage threshold value and outputting a first voltage comparison result;
and the complementary output generator is connected with the voltage comparator and used for receiving the first voltage comparison result and judging whether to stop outputting the pulse width modulation signal according to the first voltage comparison result.
3. The power supply of claim 2, wherein the control circuit further comprises:
the digital-to-analog converter is used for performing digital-to-analog conversion on the corresponding current value in the current instruction to obtain analog voltage;
the operational amplifier and the digital-to-analog converter are used for receiving the analog voltage output by the digital-to-analog converter and comparing the analog voltage with the fed-back average voltage to obtain a second voltage comparison result;
the complementary output generator is further configured to adjust a duty ratio of the output pulse width modulation signal according to the second voltage comparison result fed back by the operational amplifier.
4. The power supply of claim 3, wherein the control circuit further comprises:
the slope compensator is connected with the operational amplifier and is used for correcting the signal output by the operational amplifier;
the current comparator is connected with the slope compensator and the complementary output generator and used for receiving the peak current, comparing the peak current with a preset current threshold and outputting a current comparison result;
and the complementary output generator is also used for receiving the current comparison result and judging whether to stop outputting the pulse width modulation signal according to the current comparison result.
5. The power supply of claim 4, wherein the constant current circuit further comprises:
the first amplifying circuit is connected with the average current detecting circuit and used for amplifying the voltage feedback signal and inputting the amplified signal to the feedback compensating circuit;
and the second amplifying circuit is connected with the peak current detecting circuit and used for amplifying the peak current and inputting the amplified signal to the current comparator.
6. The power supply of claim 3,
the feedback compensation circuit comprises a compensation circuit and a feedback circuit which are connected with each other, and the feedback circuit is used for receiving the voltage feedback signal and inputting the voltage feedback signal to the inverting input end of the operational amplifier; the feedback circuit is used for receiving the signal output by the operational amplifier so as to compensate the signal input to the inverting input end of the operational amplifier.
7. The power supply of claim 2, wherein the control circuit further comprises:
the complementary output generator is also used for stopping outputting the pulse width modulation signal to the constant current circuit when the voltage output by the constant current circuit is greater than the preset voltage threshold; or when the peak current is larger than the preset current threshold, stopping outputting the pulse width modulation signal to the constant current circuit.
8. The power supply of claim 2,
the constant current circuit further comprises an overvoltage protection circuit, wherein the overvoltage protection circuit is connected with the voltage reduction circuit and used for converting the dynamic voltage of the positive electrode of the power supply and the dynamic voltage of the negative electrode of the power supply into static voltage and feeding the static voltage back to the control circuit, so that the control circuit stops outputting the pulse width modulation signal after detecting that the voltage output by the constant current circuit is larger than the preset voltage threshold value.
9. The power supply of claim 4, wherein the control circuit further comprises:
the pulse width modulation circuit is connected with the complementary output generator and is used for generating a pulse signal and outputting the pulse signal to the complementary output generator;
a digital signal modulator connected to the complementary output generator for outputting a digital modulation signal to the complementary output generator, so that the complementary output generator adjusts the output pulse width modulation signal according to the digital modulation signal, the pulse signal and the signal output by the current comparator;
and the configurable logic unit is connected with the digital signal modulator and is used for processing the input enable signal so as to control the complementary output generator through the digital signal modulator.
10. A light source system, comprising:
the processing circuit is used for receiving an image signal, processing the image signal to obtain a corresponding current value, and generating a current instruction according to the current value;
the power supply is connected with the processing circuit and used for receiving the current instruction and outputting a constant current value corresponding to the current instruction;
the light source is connected with the power supply and is used for receiving the current value output by the power supply and emitting light with corresponding brightness;
wherein the power supply is the power supply of any one of claims 1-9.
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| CN202021077984.0U CN212851136U (en) | 2020-06-11 | 2020-06-11 | Power supply and light source system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115360888A (en) * | 2022-10-19 | 2022-11-18 | 深圳市联明电源有限公司 | Constant current driving circuit and driving method applied to laser pumping |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115360888A (en) * | 2022-10-19 | 2022-11-18 | 深圳市联明电源有限公司 | Constant current driving circuit and driving method applied to laser pumping |
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