CN112135388A - Drive circuit of LED projection lamp and control method thereof - Google Patents
Drive circuit of LED projection lamp and control method thereof Download PDFInfo
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- CN112135388A CN112135388A CN202010947533.6A CN202010947533A CN112135388A CN 112135388 A CN112135388 A CN 112135388A CN 202010947533 A CN202010947533 A CN 202010947533A CN 112135388 A CN112135388 A CN 112135388A
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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]
- H05B45/30—Driver circuits
- H05B45/32—Pulse-control circuits
- H05B45/325—Pulse-width modulation [PWM]
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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
- H05B45/12—Controlling the intensity of the light using optical feedback
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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]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
Abstract
A driving circuit of an LED projection lamp and a control method thereof are provided. The projection lamp light source array formed by m groups of n LED light-emitting elements in each group is provided with two driving units which are respectively used for driving LED light-emitting elements in each row and each column. Before working, the invention firstly collects the driving current used for checking the working state of the circuit under different driving states and the illumination intensity output by each LED luminous element. Therefore, the LED driving circuit can obtain all selectable driving states in a table look-up mode, and then screen the driving states according to whether the LED light-emitting elements required by each driving state can work normally, and after screening, the LED driving circuit can realize the output of the illumination intensity meeting the requirements by setting the corresponding duty ratio of the driving signals. The invention can judge whether each LED luminous element works normally by checking the magnitude of the driving current, thereby avoiding the damaged LED luminous element, ensuring the output of the illumination intensity and simultaneously reducing the overall power consumption of the circuit.
Description
Technical Field
The invention relates to an LED projection lamp, in particular to a driving circuit of the LED projection lamp and a control method thereof.
Background
The LED projection lamp is commonly used for lighting of building outer walls, building bodies, corridor columns, squares and gardens. Outdoor night light is limited, so the LED projection lamp is generally required to be set as a high-power and high-lumen light source. Therefore, it is often necessary to arrange an array of LEDs within an LED projector to provide sufficient illumination intensity.
However, due to its own characteristics, LED devices can collect a large amount of heat in their package structures during long-term high-power light emission. The high-power LED requires a larger driving current, and thus a large amount of heat is generated in the driving circuit and the current stabilizing circuit connected thereto. Because the LED projector typically needs to be lit overnight, long-term high-power operation can significantly shorten the life of the projector.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a driving circuit of an LED projection lamp and a control method thereof, and the driving circuit can intermittently light different LED elements by designing an LED array driving circuit, so as to realize dynamic and stable light source output, thereby reducing the power consumption of the whole projection lamp and reducing the working current of the LED projection lamp. The invention specifically adopts the following technical scheme.
Firstly, in order to achieve the above purpose, a driving circuit of an LED projection lamp is provided, where LED light emitting elements connected to the driving circuit include m groups, each group includes n LED light emitting elements, the n LED light emitting elements in each group are connected in series, and m and n are integers greater than 1;
the drive circuit of LED projecting lamp includes: the output ends of the first driving units are respectively connected with the anodes of the m groups of LED light-emitting elements and are used for respectively providing driving voltage or turn-off voltage for the groups of LED light-emitting elements; each output end of the second driving unit is respectively and simultaneously connected with the cathodes of the m LED light-emitting elements which are arranged in the same order in the m groups of LED light-emitting elements, and the second driving unit is used for respectively providing turn-off voltage or driving voltage for each group of LED light-emitting elements; the input end of the detection circuit is simultaneously connected with the cathodes of the m groups of LED light-emitting elements and is used for receiving the driving current of each group of LED light-emitting elements and sampling the driving current; the sampling port of the control unit is connected with the output end of the detection circuit and is used for receiving sampling signals of the detection circuit for the driving current of each group of LED light-emitting elements, and the output port of the control unit is respectively connected with the input end of the first driving unit and the input end of the second driving unit and is used for respectively controlling the driving voltage or the turn-off voltage output by the output ends of the first driving unit and the second driving unit; the control unit is also provided with a checking module which is used for checking whether a sampling signal of the driving current of each group of LED light-emitting elements corresponds to the driving voltage or not according to the driving voltage output by the output ends of the first driving unit and the second driving unit, triggering the control unit to output a control signal to scan the m × n LED light-emitting elements when the sampling signal does not correspond to the driving voltage, updating the driving state of the fault LED light-emitting elements obtained in the scanning process, setting the control unit to avoid the fault LED light-emitting elements when the control unit resumes outputting the driving voltage to each LED light-emitting element after the scanning is finished, and compensating the illumination intensity provided by the fault LED light-emitting elements by using the LED light-emitting elements which normally work around the fault LED light-emitting elements.
Optionally, as to any one of the above driving circuits of the LED projection lamp, each output terminal of the first driving unit and the second driving unit is respectively connected to a BUCK circuit that is independent of each other, and each BUCK circuit respectively includes: the input end of the switching tube T1 is connected with the driving power supply, and the control end of the switching tube T1 is connected with the output port of the control unit; a follow current tube Q1 connected between the output end of the switch tube T1 and the ground level; an energy storage inductor L, one end of which is connected between the output end of the switch tube T1 and the common end of the follow current tube Q1; and the filter capacitor C is connected between the other end of the energy storage inductor L and the ground level, and is connected between the positive electrode and the negative electrode of the n LED light-emitting elements in one group in parallel.
Optionally, as to any one of the above driving circuits for an LED projection lamp, a current follower circuit is further connected between the input terminal of the detection circuit and the negative electrode of each group of LED light emitting elements, and the current follower circuit includes: the current follower Q2 has a grounded base, an emitter connected to the cathode of one set of the LED light emitting elements through an emitter resistor Re, and a collector connected to the cathode of the other set of the LED light emitting elements through a collector capacitor Cc or to the input terminal of the detection circuit.
Optionally, as mentioned in any one of the above, the driving circuit of the LED projector, wherein the detection circuit includes: a second input end of the optical coupling isolation device U1 is connected with a ground level; the first resistor R1 is connected between the optocoupler power supply signal V1 and a first output end of the optocoupler isolation device U1; a second resistor R2, which is connected between the first input end of the light coupling isolation device U1 and the collector capacitor Cc of the detection circuit, or which is connected between the first input end of the light coupling isolation device U1 and the cathode of the group of LED light emitting elements; a third resistor R3, a first end of which is connected to the common end of the second resistor R2 and the detection circuit, or a first end of which is connected between the second resistor R2 and the cathode of the group of LED light-emitting elements, and a second end of which is connected to the second input end of the optocoupler isolation device U1; and the fourth resistor R4 is connected between the first output end and the second output end of the optical coupling isolation device U1, and the common end of the fourth resistor R4 and the first resistor R1 is connected to the sampling port of the control unit.
Meanwhile, in order to achieve the above object, the present invention further provides a method for controlling a driving circuit of an LED projector, which is applied to the driving circuit of the LED projector, and includes the steps of:
the first step, initialization, the control unit outputs control signals to control the output ends of the first driving unit and the second driving unit to output corresponding driving voltage or turn-off voltage, scanning the M x N LED luminous elements, recording the drive current and the whole illumination intensity of the LED luminous elements respectively corresponding to each drive state obtained by the detection circuit in the scanning process, establishing a state matrix T [ l, s, M, N ] of the LED projection lamp, wherein, M is a first voltage output vector corresponding to the driving state of each output end of the first driving unit, N is a second voltage output vector corresponding to the driving state of each output end of the second driving unit, s is a sampling signal corresponding to the driving voltage output by each output end of the first and second driving units, and l is the illumination brightness corresponding to the driving voltage output by each output end of the first and second driving units;
secondly, detecting the current ambient light intensity as L, and calculating the illumination brightness of the target according to the current ambient light intensity L
Thirdly, according to the illumination brightness of the targetL 'finds that the lighting brightness L in the state matrix T reaches L' elements of the brightness respectively as [ L1，s1，M1，N1]，...，[li，si，Mi，Ni]，...，[ll′，sl′，Ml′，Nl′]Setting the duty ratio of the PWM wave corresponding to the driving state as L according to the ratio relation between the illumination brightness L and the target illumination brightness L' in the state matrix TiL ', where i denotes the number of the element whose illumination luminance reaches the target illumination luminance L ', i ∈ [1, L ']；
Fourthly, controlling the driving states of each output end of the first driving unit and each output end of the second driving unit to be [ l1，s1，M1，N1]，...，[li，si，Mi，Ni]，...，[ll′，sl′，Ml′，Nl′]Skipping between the driving states, controlling the duty ratio of the corresponding PWM wave under each driving state to be respectively corresponding to liand/L', simultaneously checking whether the sampling signals in each driving state are consistent with the sampling signals s correspondingly recorded in the state matrix T or not by the detection circuit, triggering the control unit to output control signals to scan the m × n LED light-emitting elements when the sampling signals are not consistent with the sampling signals s correspondingly recorded in the state matrix T, updating the driving state of the fault LED light-emitting element obtained in the scanning process, setting the control unit to avoid the fault LED light-emitting element when the control unit resumes outputting the driving voltage to each LED light-emitting element after the scanning is finished, and compensating the illumination intensity provided by the fault LED light-emitting element by using the normally working LED light-emitting elements around the fault LED light-emitting element.
Optionally, the method for controlling a driving circuit of an LED projection lamp as described in any of the above, wherein the step of triggering the control unit to output the control signal to scan the m × n LED light emitting elements when the driving states of the faulty LED light emitting elements obtained in the scanning process are not consistent specifically includes:
and according to the sequence of the first step, the control unit outputs control signals, respectively controls each output end of the first driving unit and each output end of the second driving unit to output corresponding driving voltage or turn-off voltage, scans the M x N LED light-emitting elements, verifies whether the driving current which respectively corresponds to each LED light-emitting element in each driving state and is obtained by the detection circuit in the scanning process is consistent with the data recorded in the state matrix T [ l, s, M, N ] obtained by initialization, and deletes the element corresponding to the driving state from the state matrix T [ l, s, M, N ] when the driving current is inconsistent.
Optionally, the method for controlling the driving circuit of the LED projector as described above, wherein the controlling unit is configured to avoid the faulty LED lighting element when the controlling unit resumes outputting the driving voltage to each LED lighting element after the scanning is finished, and compensate the illumination intensity provided by the faulty LED lighting element by using the LED lighting elements that normally operate around the faulty LED lighting element, and the method specifically includes the following steps:
controlling a state matrix T [ l, s, M, N of the deleted driving states of the output terminals of the first driving unit and the second driving unit]Skipping between elements with the medium corresponding illumination brightness L reaching the target illumination brightness L', and controlling the duty ratio of the corresponding PWM wave to be L respectively under each driving statei/L′。
Optionally, the method for controlling the driving circuit of the LED projector as described in any of the above, wherein in the fourth step, the driving states of the output terminals of the first driving unit and the second driving unit are controlled to be [ l ] every K clock cycles of the control unit1，s1，M1，N1]，...，[li，si，Mi，Ni]，...，[ll′，sl′，Mc，Nl′]Jump between them once, K is more than 10.
Optionally, the method for controlling the driving circuit of the LED projector as described in any of the above, wherein the PWM wave duty ratios are uniformly distributed in K clock cycles of the control unit.
Advantageous effects
The projection lamp light source array formed by m groups of n LED light-emitting elements in each group is provided with two driving units which are respectively used for driving LED light-emitting elements in each row and each column in the array. Before working, the invention firstly collects the driving current used for checking the working state of the circuit under different driving states and the illumination intensity output by each LED light-emitting element combination. Therefore, when the LED driving circuit works, all selectable driving states can be obtained directly in a table look-up mode, then the driving states are screened according to whether the LED light-emitting elements required by all the driving states can work normally, and after screening, the LED driving circuit can achieve the illumination intensity output meeting the requirements by setting the corresponding duty ratio of the driving signals. The invention can judge whether each LED luminous element works normally by checking the magnitude of the driving current, thereby avoiding the damaged LED luminous element by screening the driving state, ensuring the output of the illumination intensity and reducing the overall power consumption of the circuit.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic circuit diagram of a driving circuit of an LED projector according to the present invention in one implementation;
fig. 2 is a schematic circuit diagram of a driving circuit of the LED projector according to a second implementation manner;
fig. 3 is a schematic diagram of a BUCK circuit used in a driving unit of the driving circuit of the LED projector according to the present invention.
Detailed Description
In order to make the purpose and technical solution of the embodiments of the present invention clearer, the technical solution of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Fig. 1 is a driving circuit of an LED projection lamp according to the present invention, the LED light emitting elements connected to the driving circuit include m groups, each group includes n LED light emitting elements, and the n LED light emitting elements in each group are connected in series to form an m × n LED light emitting element array. Wherein m and n are integers more than 1;
the invention provides m columns and n rows of the m x n LED light-emitting element array with the following driving circuits capable of providing enough illumination intensity for the projection lamp:
the first output end of the first driving unit is connected with the anodes of the first group of LED light-emitting elements corresponding to the first row, the second output end of the first driving unit is connected with the anodes of the second group of LED light-emitting elements corresponding to the second row, and so on, and the mth output end of the first driving unit is connected with the anodes of the mth group of LED light-emitting elements corresponding to the mth row, and is used for respectively providing driving voltage or turn-off voltage for each group of LED light-emitting elements;
the first output end of the second driving unit is simultaneously connected with the cathodes of the m LED light-emitting elements which are arranged in the first order in the m groups of LED light-emitting elements, the second output end of the second driving unit is simultaneously connected with the cathodes of the m LED light-emitting elements which are arranged in the second order in the m groups of LED light-emitting elements, and so on, the nth output end of the second driving unit is simultaneously connected with the cathodes of the m LED light-emitting elements which are arranged in the nth order in the m groups of LED light-emitting elements and is used for respectively providing turn-off voltage or driving voltage for each group of LED light-emitting elements;
the input end of the detection circuit is simultaneously connected with the cathodes of the m groups of LED light-emitting elements and is used for receiving all the driving currents of the groups of LED light-emitting elements and sampling the driving currents;
a sampling port of the control unit is connected with the output end of the detection circuit and is used for receiving a sampling signal C1 of the detection circuit for the driving current of each group of LED light-emitting elements, and an output port of the control unit is respectively connected with the input end of the first driving unit and the input end of the second driving unit and is used for respectively controlling the driving voltage or the turn-off voltage output by the output ends of the first driving unit and the second driving unit and switching the driving state of each LED light-emitting element;
the control unit is also provided with a checking module which is used for checking whether the comparison between the sampling signals of the driving current of each group of LED luminous elements and the pre-recorded normal values by the detection circuit is corresponding to the values in the driving voltage state output by each driving unit or not according to the driving voltage output by the output ends of the first driving unit and the second driving unit, triggering the control unit to output a control signal to scan the m x n LED light-emitting elements when the LED light-emitting elements do not correspond to each other, updating the driving state of the failed LED light-emitting element obtained in the scanning process, setting the control unit to avoid the failed LED light-emitting element when the control unit resumes outputting the driving voltage to each LED light-emitting element after the scanning is finished, and the driving state corresponding to the LED luminous element which can normally work around the fault LED luminous element is utilized to compensate the illumination intensity which is originally required to be provided by the fault LED luminous element.
Referring to fig. 2, in the driving circuit of the LED projector, a current follower circuit shown in the lower part of fig. 2 may be further disposed between the input terminal of the detection circuit and the negative electrode of each group of LED light-emitting elements. The current follower circuit can be sequentially cascaded between the cathodes of the LED light-emitting elements of each group, and the transmission of the driving current of each group is realized through a current follower tube Q2 formed by BJT triodes. Taking any one of the current follower circuits as an example, the current follower Q2 has a grounded base, an emitter connected to the cathode of a group of LED light emitting elements located at the nth position through an emitter resistor Re, and a collector connected to the cathode of another group of LED light emitting elements through a collector capacitor Cc or connected to the input terminal of the detection circuit. The direct current gain of the current follower circuit is close to 1 and is always less than 1, namely no current gain exists, so that the output current is approximately equal to the input current, the output voltage is equal to the input voltage, the driving current passed by each sequential LED light-emitting element in each group of LED light-emitting elements can be gradually converged from the last group to the negative electrode of the nth sequential LED light-emitting element with the first group m being 1, and therefore the whole driving current of each group of LED light-emitting elements is sampled through the input end of the detection circuit and fed back to the control unit for identifying the driving state of the LED light-emitting elements in the array. The current follower circuit has the characteristics of small input resistance and large output resistance. Therefore, although the common base circuit current follower does not have a voltage amplification effect, the input and the output of the common base circuit current follower are in the same phase, and the common base circuit current follower has good frequency characteristics, so that the common base circuit current follower can be used in a driving circuit which is driven based on a PWM wave and switches the state of an LED circuit at a higher frequency. Because the output resistance is very high, the influence of Early effect is basically avoided, and the input signal of the detection circuit can be ensured to be correct, so that the driving current for marking the driving state of the circuit can be accurately acquired.
The first driving unit and the second driving unit can be realized by a plurality of sets of BUCK circuits shown in fig. 3. Each output end of the first driving unit and each output end of the second driving unit are respectively connected with a BUCK circuit which is independent of each other, wherein a unit which is formed by each BUCK circuit and used for outputting a driving signal respectively comprises:
the input end of the switching tube T1 is connected with the driving power supply, and the control end of the switching tube T1 is connected with the output port of the control unit;
a follow current tube Q1 connected between the output end of the switch tube T1 and the ground level;
an energy storage inductor L, one end of which is connected between the output end of the switch tube T1 and the common end of the follow current tube Q1;
and the filter capacitor C is connected between the other end of the energy storage inductor L and the ground level, and is connected between the positive electrode and the negative electrode of the n LED light-emitting elements in one group in parallel.
The on-off of the switch tube T1 in the BUCK circuit is controlled by the driving pulse output by the control unit: when the control unit outputs a high level, the T1 is turned on, the voltage of the positive electrode of the follow current tube Q1 is 0, the voltage of the negative electrode of the follow current tube Q1 is the voltage of the driving power supply, and the current flowing when the T1 is turned on charges the energy storage inductor L and supplies power to the group of LED light-emitting elements connected to the other end of the energy storage inductor L. When the control unit outputs a low level, the self-inductance potential of the energy storage inductor L prevents the current from dropping, so that the follow current tube Q1 is conducted in the forward direction, and the electric energy stored in the energy storage inductor L supplies power to the LED light-emitting element for a short time. And the filter capacitor C in the BUCK circuit can reduce the fluctuation of the output voltage. From this, this BUCK circuit can switch LED light emitting component's drive state with comparatively steady mode, and the luminous intensity obviously changes when avoiding PWM ripples drive state to change, guarantees that projecting lamp output light intensity does not hop, guarantees illuminating effect.
In order to avoid the influence of the variation of the driving current on the sampling of the control unit, the detection circuit used in the invention can be specifically configured to include:
a second input end of the optical coupling isolation device U1 is connected with a ground level;
the first resistor R1 is connected between the optocoupler power supply signal V1 and a first output end of the optocoupler isolation device U1;
a second resistor R2, which is connected between the first input end of the light coupling isolation device U1 and the collector capacitor Cc of the detection circuit, or which is connected between the first input end of the light coupling isolation device U1 and the cathode of the group of LED light emitting elements;
a third resistor R3, a first end of which is connected to the common end of the second resistor R2 and the detection circuit, or a first end of which is connected between the second resistor R2 and the cathode of the group of LED light-emitting elements, and a second end of which is connected to the second input end of the optocoupler isolation device U1;
and the fourth resistor R4 is connected between the first output end and the second output end of the optical coupling isolation device U1, and the common end of the fourth resistor R4 and the first resistor R1 is connected to the sampling port of the control unit.
Therefore, the detection circuit can shunt all the driving currents of all the groups of LED light-emitting elements at the input end of the optical coupling isolation device U1 according to a fixed proportion through the second resistor R2 and the third resistor R3, and the driving currents are sampled through the optical coupling isolation device U1 realized by TLP2160, so that the phenomenon that the sampling receiving end of the control unit is abnormal due to the change of the driving currents is avoided.
The following describes in detail a driving circuit control method of an LED projector according to the present invention, taking an LED light emitting element array with n being 4 and m being 3 as an example:
the first step, initialization, the control unit outputs control signals to control the 3 output ends of the first driving unit and the 4 output ends of the second driving unit to output corresponding driving voltages or turn-off voltages respectively, and traverse all 23×24In the drive state, 3 × 4 LED light emitting elements are scanned. In the scanning process, the first driving unit can be kept in a driving state, the driving state of the second driving unit is sequentially changed, the driving current and the integral illumination intensity of each LED light-emitting element under each driving state obtained by the detection circuit in the scanning process are recorded, and a state matrix T [ l, s, M, N ] of the LED projection lamp is established]Then, all the driving states of the first driving unit are gradually traversed, and the state matrix T is updated. In the state matrix T, M is a first voltage output vector corresponding to the driving state of each output terminal of the first driving unit, and the elements of the first voltage output vector are the driving voltages or turn-off voltages of 3 output terminals of the first driving unit respectively; n is a second voltage output vector corresponding to the driving state of each output end of the second driving unit, and the elements of the second voltage output vector are respectively the driving voltage or the turn-off voltage of 4 output ends of the second driving unit; s is a sampling signal corresponding to the driving voltage output by each output end of the first and second driving units, and l is the illumination brightness corresponding to the driving voltage output by each output end of the first and second driving units;
secondly, detecting that the current environment light intensity is L through a light sensor integrated on the LED projection lamp, and calculating the illumination brightness of the target according to the current environment light intensity L
Thirdly, searching for L 'elements [ L ] when the illumination brightness L reaches the brightness (1 is larger than or equal to L') in the state matrix T according to the target illumination brightness L1，s1，M1，N1]，...，[li，si，Mi，Ni]，...，[ll′，sl′，Ml′，Nl′]Respectively setting any one of the driving states (M) in the elements of the matrix according to the ratio between the illumination brightness L and the target illumination brightness L' in the matrix Ti，Ni) Has a duty ratio of a PWM wave driving signal of liL ', where i denotes the number of the element whose illumination luminance reaches the target illumination luminance L ', i ∈ [1, L ']；
Fourthly, controlling the driving states of each output end of the first driving unit and each output end of the second driving unit to be [ l1，si，M1，N1]，...，[li，si，Mi，Ni]，...，[ll′，sl′，Ml′，Nl′]Jumping between the corresponding l' driving states, controlling the duty ratio of the PWM wave of the driving signal under each driving state to be liL' and, at the same time, checks whether the sampling signal of each driving state by the detection circuit coincides with the sampling signal s recorded in the state matrix T corresponding to the driving state in the high level duration period of the PWM driving signal, triggering the control unit to output a control signal to scan all the driving states of the m x n LED light-emitting elements when the driving states are inconsistent, updating the sampling signal obtained in the scanning process and the driving state of the failed LED light-emitting element recorded in the state matrix T which is inconsistent, setting the control unit to avoid the failed LED light-emitting element when the control unit resumes outputting the driving voltage to each LED light-emitting element after the scanning is finished, and replacing the driving state containing the fault LED light-emitting element with other driving states, and compensating the illumination intensity provided by the fault LED light-emitting element by using the LED light-emitting elements which normally work around the fault LED light-emitting element.
Therefore, the invention can automatically and timely acquire the abnormal condition of the LED light-emitting element in a mode of recording and verifying the sampling signal according to the circuit characteristics and trigger the updating of the state matrix T. In order to avoid that the fault LED light emitting element affects the illumination intensity output by the projector, the invention can specifically perform the following operations in the fourth step of scanning 3 × 4 LED light emitting elements and updating the driving state of the fault LED light emitting element obtained in the scanning process:
according to the sequence of the first step, the control unit outputs control signals, the output ends of the first driving unit and the output ends of the second driving unit are respectively controlled to output corresponding driving voltage or turn-off voltage, all trigger states of all LED light-emitting elements are scanned, whether the driving current obtained by the detection circuit in the scanning process corresponding to each driving state is consistent with the data s recorded in the state matrix T [ l, s, M, N ] obtained by initialization or not is verified, and when the driving current is inconsistent with the data s, the elements corresponding to the driving states are deleted from the state matrix T [ l, s, M, N ], so that the influence of a fault LED light-emitting element on a circuit to correctly respond to the trigger state is avoided.
Therefore, by deleting each trigger state related to the fault LED light-emitting element in the state matrix T, the invention can ensure that the control unit completely avoids the fault LED light-emitting element when the control unit resumes outputting the driving voltage to each LED light-emitting element after scanning is finished, and the LED light-emitting elements which normally work around the fault LED light-emitting element are used for compensating the illumination intensity provided by the fault LED light-emitting element through other driving states. This process may be specifically performed according to the following steps:
controlling a state matrix T [ l, s, M, N of the driving states of the output terminals of the first driving unit and the output terminals of the second driving unit after deleting corresponding elements]And skipping once every K clock cycles of the interval control unit between elements of which the corresponding illumination brightness L reaches the target illumination brightness L'. Under each driving state obtained by jumping, each driving unit is controlled according to liThe duty ratio output of/L' corresponds to the PWM wave in the driving state, so that the corresponding LED luminous element can provide illumination output with proper brightness. In order to ensure that the illumination brightness cannot be suddenly changed, the invention can further specifically set the duty ratio of the PWM wave to be uniformly distributed in K clock cycles of the control unit.
Therefore, the invention can control the working time of each LED luminous element through the adjustment of the PWM wave duty ratio, reduce the heat loss of the device, reduce the power loss, control the heat output of the circuit device and ensure the service life of the circuit.
The above are merely embodiments of the present invention, which are described in detail and with particularity, and therefore should not be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the present invention, and these changes and modifications are within the scope of the present invention.
Claims (9)
1. A drive circuit of an LED projection lamp is characterized in that,
the LED light-emitting elements connected with the driving circuit comprise m groups, each group comprises n LED light-emitting elements, the n LED light-emitting elements in each group are connected in series, and m and n are integers more than 1; the drive circuit of LED projecting lamp includes:
the output ends of the first driving units are respectively connected with the anodes of the m groups of LED light-emitting elements and are used for respectively providing driving voltage or turn-off voltage for the groups of LED light-emitting elements;
each output end of the second driving unit is respectively and simultaneously connected with the cathodes of the m LED light-emitting elements which are arranged in the same order in the m groups of LED light-emitting elements, and the second driving unit is used for respectively providing turn-off voltage or driving voltage for each group of LED light-emitting elements;
the input end of the detection circuit is simultaneously connected with the cathodes of the m groups of LED light-emitting elements and is used for receiving the driving current of each group of LED light-emitting elements and sampling the driving current;
the sampling port of the control unit is connected with the output end of the detection circuit and is used for receiving sampling signals of the detection circuit for the driving current of each group of LED light-emitting elements, and the output port of the control unit is respectively connected with the input end of the first driving unit and the input end of the second driving unit and is used for respectively controlling the driving voltage or the turn-off voltage output by the output ends of the first driving unit and the second driving unit;
the control unit is also provided with a checking module which is used for checking whether a sampling signal of the driving current of each group of LED light-emitting elements corresponds to the driving voltage or not according to the driving voltage output by the output ends of the first driving unit and the second driving unit, triggering the control unit to output a control signal to scan the m × n LED light-emitting elements when the sampling signal does not correspond to the driving voltage, updating the driving state of the fault LED light-emitting elements obtained in the scanning process, setting the control unit to avoid the fault LED light-emitting elements when the control unit resumes outputting the driving voltage to each LED light-emitting element after the scanning is finished, and compensating the illumination intensity provided by the fault LED light-emitting elements by using the LED light-emitting elements which normally work around the fault LED light-emitting elements.
2. The driving circuit of the LED spot light of claim 1, wherein each output terminal of the first driving unit and the second driving unit is connected to a BUCK circuit, and each BUCK circuit comprises:
a switch tube (T1), the input end of which is connected with the driving power supply, and the control end of which is connected with the output port of the control unit;
a follow current tube (Q1) connected between the output end of the switch tube (T1) and the ground level;
an energy storage inductor (L) with one end connected between the output end of the switch tube (T1) and the common end of the follow current tube (Q1);
and the filter capacitor (C) is connected between the other end of the energy storage inductor (L) and the ground level, and is connected between the positive pole and the negative pole of the n LED light-emitting elements in one group in parallel.
3. The driving circuit of the LED light projector according to claim 1, wherein a current follower circuit is further connected between the input terminal of the detection circuit and the negative electrode of each group of LED light emitting elements, and the current follower circuit comprises:
and the base of the current follower tube (Q2) is grounded, the emitter of the current follower tube is connected to the cathode of one group of LED luminous elements through an emitter resistor (Re), and the collector of the current follower tube is connected to the cathode of the other group of LED luminous elements through a collector capacitor (Cc) or connected to the input end of the detection circuit.
4. The driving circuit of an LED floodlight of claim 3, wherein the detection circuit comprises:
the second input end of the optical coupling isolation device (U1) is connected with the ground level;
a first resistor (R1) connected between the optocoupler supply signal (V1) and a first output of the optocoupler isolation device (U1);
a second resistor (R2) connected between the first input end of the light coupling isolation device (U1) and the collector capacitance (Cc) of the detection circuit, or connected between the first input end of the light coupling isolation device (U1) and the cathode of the group of LED light-emitting elements;
a third resistor (R3), the first end of which is connected with the common end of the second resistor (R2) and the detection circuit, or the first end of which is connected between the second resistor (R2) and the cathode of the group of LED luminous elements, and the second end of which is connected with the second input end of the optical coupling isolation device (U1);
and the fourth resistor (R4) is connected between the first output end and the second output end of the optical coupling isolation device (U1), and the common end of the fourth resistor and the first resistor (R1) is connected to the sampling port of the control unit.
5. A method for controlling a driving circuit of an LED projector according to claims 1 to 4, wherein the method comprises the steps of:
the first step, initialization, the control unit outputs control signals to control the output ends of the first driving unit and the second driving unit to output corresponding driving voltage or turn-off voltage, scanning the M x N LED luminous elements, recording the drive current and the whole illumination intensity of the LED luminous elements respectively corresponding to each drive state obtained by the detection circuit in the scanning process, establishing a state matrix T [ l, s, M, N ] of the LED projection lamp, wherein, M is a first voltage output vector corresponding to the driving state of each output end of the first driving unit, N is a second voltage output vector corresponding to the driving state of each output end of the second driving unit, s is a sampling signal corresponding to the driving voltage output by each output end of the first and second driving units, and l is the illumination brightness corresponding to the driving voltage output by each output end of the first and second driving units;
secondly, detecting the current ambient light intensity as L, and calculating the illumination brightness of the target according to the current ambient light intensity L
Thirdly, searching the state matrix T according to the target illumination brightness L ', wherein the L' elements of the state matrix T when the illumination brightness L reaches the brightness are respectively [ L1,s1,M1,N1],...,[li,si,Mi,Ni],...,[ll',sl',Ml',Nl']Setting the duty ratio of the PWM wave corresponding to the driving state as L according to the ratio relation between the illumination brightness L and the target illumination brightness L' in the state matrix TiL ', where i denotes the number of the element whose illumination luminance reaches the target illumination luminance L ', i ∈ [1, L ']；
Fourthly, controlling the driving states of each output end of the first driving unit and each output end of the second driving unit to be [ l1,s1,M1,N1],...,[li,si,Mi,Ni],...,[ll',sl',Ml',Nl']Skipping between the driving states, controlling the duty ratio of the corresponding PWM wave under each driving state to be respectively corresponding to liL' and simultaneously checking whether the sampling signals in each driving state are consistent with the sampling signals s correspondingly recorded in the state matrix T or not by the detection circuit, triggering the control unit to output control signals to scan the m-n LED light-emitting elements when the sampling signals are not consistent with the sampling signals s correspondingly recorded in the state matrix T, updating the driving state of the fault LED light-emitting element obtained in the scanning process, setting the control unit to avoid the fault LED light-emitting element when the control unit recovers to output driving voltage to each LED light-emitting element after the scanning is finished, and compensating the fault LED light-emitting element by using the normally working LED light-emitting elements around the fault LED light-emitting elementThe intensity of the light provided by the element.
6. The method according to claim 5, wherein the step of triggering the control unit to output the control signal to scan the m × n LED light emitting elements when the driving states of the faulty LED light emitting elements obtained in the scanning process are not consistent includes:
and according to the sequence of the first step, the control unit outputs control signals, respectively controls each output end of the first driving unit and each output end of the second driving unit to output corresponding driving voltage or turn-off voltage, scans the M x N LED light-emitting elements, verifies whether the driving current which respectively corresponds to each LED light-emitting element in each driving state and is obtained by the detection circuit in the scanning process is consistent with the data recorded in the state matrix T [ l, s, M, N ] obtained by initialization, and deletes the element corresponding to the driving state from the state matrix T [ l, s, M, N ] when the driving current is inconsistent.
7. The method for controlling the driving circuit of the LED projector according to claim 6, wherein the control unit is configured to avoid the faulty LED lighting element when the control unit resumes outputting the driving voltage to the LED lighting elements after the scanning is finished, and compensate the illumination intensity provided by the faulty LED lighting element by using the LED lighting elements that normally operate around the faulty LED lighting element, and the method specifically comprises the following steps:
controlling a state matrix T [ l, s, M, N of the deleted driving states of the output terminals of the first driving unit and the second driving unit]Skipping between elements with the medium corresponding illumination brightness L reaching the target illumination brightness L', and controlling the duty ratio of the corresponding PWM wave to be L respectively under each driving statei/L'。
8. The method of claim 6, wherein in the fourth step, the driving states of the outputs of the first driving unit and the outputs of the second driving unit are controlled to [ l ] every K clock cycles of the control unit1,s1,M1,N1],...,[li,si,Mi,Ni],...,[ll',sl',Ml',Nl']Jump between once, K>10。
9. The method for controlling the driving circuit of the LED light projector according to claims 1 to 8, wherein the PWM wave duty ratio is uniformly distributed in K clock cycles of the control unit.
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