CN111683437B

CN111683437B - LED drive circuit and projector

Info

Publication number: CN111683437B
Application number: CN202010804177.2A
Authority: CN
Inventors: 刘林; 吴鹏军; 王鑫
Original assignee: Chengdu Jimi Technology Co Ltd
Current assignee: Chengdu Jimi Technology Co Ltd
Priority date: 2020-08-12
Filing date: 2020-08-12
Publication date: 2020-11-10
Anticipated expiration: 2040-08-12
Also published as: CN111683437A

Abstract

The application discloses an LED drive circuit and a projector, belonging to the technical field of LEDs, wherein the LED drive circuit is applied to a multi-lamp system, wherein an LED drive chip and RGB three-way LED lamps are arranged in the multi-lamp system, and one or more LED lamps are connected in series on a target circuit of the RGB three-way LED lamps; the method comprises the following steps: the three-way LED lamp comprises three capacitors, three sampling units, a first switch unit, a second switch unit and a third switch unit, wherein the first switch unit, the second switch unit and the third switch unit are respectively used for controlling the RGB three-way LED lamp to be independently switched on or switched off. Obviously, because the voltages at the two ends of the capacitors of the three capacitors cannot change suddenly, when the switch unit receives a target control signal, the switch unit can control the first capacitor, the second capacitor and the third capacitor to quickly release the voltage difference generated when the multi-lamp system is switched on, so that the current overshoot phenomenon generated when the LED driving chip drives the multi-lamp system can be avoided.

Description

LED drive circuit and projector

Technical Field

The invention relates to the technical field of LEDs, in particular to an LED driving circuit and a projector.

Background

A projector is a common electronic device in daily life and study, and in the prior art, an RGB three-way LED lamp is usually used as a light source of the projector, and an LED (light Emitting Diode) driving chip is used to drive the light source of the projector. However, sometimes, in order to increase the display effect of the projector light source, one or more LED lamps are additionally connected in series to the RGB three-way LED lamps to adjust the brightness, hue and saturation of the projector light source, that is, the multi-lamp system is used as the light source to adjust the display effect of the projector light source. The breakover voltage of the RGB three-way LED lamp is about 3-4.5V, the overshoot current is within 1A, the series breakover voltage of the multi-lamp system is generally more than 7V, the overshoot current during switching of the multi-lamp system can reach more than 10A and far exceeds the upper limit of the current which can be borne by the LED lamp, and therefore the LED driving chip has great potential safety hazards. At present, no effective solution exists for the technical problem.

Therefore, how to avoid the current overshoot phenomenon generated by the LED driving chip in the driving process of the multi-lamp system is a technical problem to be solved urgently by those skilled in the art.

Disclosure of Invention

In view of the above, the present invention provides an LED driving circuit and a projector to avoid current overshoot generated by an LED driving chip during driving a multi-lamp system. The specific scheme is as follows:

an LED drive circuit is applied to a multi-lamp system, wherein an LED drive chip and RGB three-way LED lamps are arranged in the multi-lamp system, and one or more LED lamps are connected in series on a target circuit of the RGB three-way LED lamps; the method comprises the following steps: the RGB three-way LED lamp driving circuit comprises a first capacitor, a second capacitor, a third capacitor, a first sampling unit, a second sampling unit, a third sampling unit, a first switch unit, a second switch unit and a third switch unit, wherein the first switch unit, the second switch unit and the third switch unit are respectively used for controlling the RGB three-way LED lamp to be independently switched on or switched off according to a target control signal;

the first end of the first capacitor, the first end of the second capacitor and the first end of the third capacitor are respectively connected with the LED driving chip, and the second end of the first capacitor is respectively connected with the first sampling unit and the first switch unit; a second end of the second capacitor is connected with the second sampling unit and the second switch unit respectively, and a second end of the third capacitor is connected with the third sampling unit and the third switch unit respectively; the first sampling unit, the second sampling unit and the third sampling unit are used for sampling minimum voltage values in the first capacitor, the second capacitor and the third capacitor and feeding the minimum voltage values back to the LED driving chip, so that the LED driving chip sends the target control signals for controlling the multi-lamp system to operate to the first switch unit, the second switch unit and the third switch unit according to the minimum voltage values.

Preferably, the first sampling unit and/or the second sampling unit and/or the third sampling unit are arranged in the same or different manners.

Preferably, the first sampling unit comprises a first diode and a second diode;

the cathode of the first diode is connected with the second end of the first capacitor, the anode of the first diode is connected with the anode of the second diode, and the cathode of the second diode is grounded.

Preferably, the first capacitor, the second capacitor and the third capacitor are arranged in the same manner.

Preferably, the first capacitor is specifically an electrolytic capacitor or a tantalum capacitor or a solid capacitor.

Preferably, the first switch unit, the second switch unit and the third switch unit are arranged in the same manner.

Preferably, the first switch unit comprises a first switch tube and a second switch tube;

the source electrode of the first switch tube is connected with the second end of the first capacitor, the drain electrode of the first switch tube is connected with the drain electrode of the second switch tube, the grid electrode of the first switch tube is connected with the grid electrode of the second switch tube, and the source electrode of the second switch tube is grounded.

Preferably, the first switch tube and the second switch tube are NMOS tubes.

Correspondingly, the invention also discloses a projector which comprises the LED driving circuit disclosed in the foregoing.

Therefore, in the LED driving circuit provided by the present invention, because the electric charges stored in the first capacitor, the second capacitor, and the third capacitor respectively correspond to the branches corresponding to the RGB three-way LED lamps in the multi-lamp system, when the multi-lamp system starts to operate, the first sampling unit, the second sampling unit, and the third sampling unit respectively sample the voltage values of the first capacitor, the second capacitor, and the third capacitor, and feed the minimum voltage value obtained by sampling back to the LED driving chip, in this case, the LED driving chip can send corresponding target control signals to the first switch unit, the second switch unit, and the third switch unit according to the minimum voltage value to control the operation of the multi-lamp system. Obviously, when the LED driving circuit is used to control a multi-lamp system to operate, because the voltages at the two ends of the first capacitor, the second capacitor and the third capacitor cannot change suddenly, when the first switch unit, the second switch unit and the third switch unit receive a target control signal, the first capacitor, the second capacitor and the third capacitor can be controlled by the target control signal to rapidly release the voltage difference generated when the multi-lamp system is switched on, so that the current overshoot phenomenon generated when the LED driving chip drives the multi-lamp system can be avoided. Accordingly, the projector provided by the invention also has the beneficial effects.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a structural diagram of an LED driving circuit according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an operation result of an LED driving circuit when an LED lamp is additionally connected in series to a green light branch of an RGB three-way LED lamp;

FIG. 3 is a block diagram of another LED driving circuit according to an embodiment of the present invention;

fig. 4 is a peripheral circuit connected between the LED driving chip DLPA3005 and the multi-lamp system.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of 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 invention.

Referring to fig. 1, fig. 1 is a structural diagram of an LED driving circuit according to an embodiment of the present invention, where the LED driving circuit is applied to a multi-lamp system, where the multi-lamp system is provided with an LED driving chip and RGB three-way LED lamps, and a target circuit of the RGB three-way LED lamps is connected in series with one or more LED lamps; the method comprises the following steps: the RGB LED lamp driving circuit comprises a first capacitor C1, a second capacitor C2, a third capacitor C3, a first sampling unit, a second sampling unit, a third sampling unit, a first switching unit, a second switching unit and a third switching unit, wherein the first switching unit, the second switching unit and the third switching unit are respectively used for controlling the RGB three-way LED lamp to be independently switched on or switched off according to a target control signal;

a first end of the first capacitor C1, a first end of the second capacitor C2 and a first end of the third capacitor C3 are respectively connected with the LED driving chip, and a second end of the first capacitor C1 is respectively connected with the first sampling unit and the first switching unit; a second end of the second capacitor C2 is connected with the second sampling unit and the second switch unit respectively, and a second end of the third capacitor C3 is connected with the third sampling unit and the third switch unit respectively; the first sampling unit, the second sampling unit and the third sampling unit are used for sampling the minimum voltage value in the first capacitor C1, the second capacitor C2 and the third capacitor C3, and feeding the minimum voltage value back to the LED driving chip, so that the LED driving chip sends a target control signal for controlling the operation of the multi-lamp system to the first switch unit, the second switch unit and the third switch unit according to the minimum voltage value.

In this embodiment, an LED driving circuit is provided, by which a current overshoot phenomenon generated during driving of a multi-lamp system by an LED driving chip can be avoided. It should be noted that the LED driving circuit provided in this embodiment is applied to a multi-lamp system, where an LED driving chip and three RGB LED lamps are provided in the multi-lamp system, and one or more LED lamps are connected in series to a target circuit of the three RGB LED lamps, where the LED lamps connected in series may be monochromatic LED lamps, or LED lamps with different colors from the original LED lamp circuit, as long as the light emitting color of the lamp circuit of the series LED lamps is consistent with the light emitting color of the original LED lamp circuit. Moreover, the target circuit of the RGB three-way LED lamp may be one of the RGB three-way LED lamps, or may be two of the RGB three-way LED lamps or three of the RGB three-way LED lamps, which is not specifically limited herein.

The LED driving circuit is provided with a first capacitor C1, a second capacitor C2, a third capacitor C3, a first sampling unit, a second sampling unit, a third sampling unit, a first switch unit, a second switch unit and a third switch unit, wherein the first switch unit, the second switch unit and the third switch unit respectively control the independent on and off of the RGB three-way LED lamp.

When the LED driving circuit starts to operate, the first sampling circuit, the second sampling circuit and the third sampling circuit can acquire minimum voltage values in the first capacitor C1, the second capacitor C2 and the third capacitor C3 and feed the acquired minimum voltage values back to the LED driving chip, and when the LED driving chip receives the minimum voltage values in the first capacitor C1, the second capacitor C2 and the third capacitor C3 fed back by the sampling circuits, the LED driving chip can send corresponding target control signals to the first switch unit, the second switch unit and the third switch unit according to the minimum voltage values to control the multi-lamp system to operate. The minimum voltage value of the first capacitor C1, the second capacitor C2 and the third capacitor C3 determines the on-state voltage of the target control signal when controlling the first switch unit and/or the second switch unit and/or the third switch unit. It is conceivable that, in the process of controlling the first, second and third switching units to be turned on or off by the target control signal, since the capacitor voltages of the first, second and third capacitors C1, C2 and C3 cannot be abruptly changed, in this case, the first, second and third capacitors C1, C2 and C3 can be controlled to be turned on or off by the respective switching units to rapidly release the voltage difference generated when the multi-lamp system is switched to be turned on. Obviously, by the arrangement mode, the phenomenon of current overshoot generated by the LED driving chip in the process of driving the multi-lamp system can be avoided.

In this embodiment, a specific example is used for explaining, assuming that when a green light branch of an RGB three-way LED lamp is additionally connected in series with a single LED lamp, when the red light branch is turned on, the voltage across the first capacitor C1 is 4V to 0V, and when the green light branch is switched on, the voltage across the second capacitor C2 becomes +4V to-4V, at this time, the second switch unit is turned on to rapidly release the voltage across the second capacitor C2, and then the voltage across the second capacitor C2 becomes 8V to 0V, so that the current overshoot phenomenon generated by the LED driving chip in the driving process of the multi-lamp system can be avoided. Referring to fig. 2, fig. 2 is a schematic diagram of an operation result of an LED driving circuit when a path of LED lamp is additionally connected in series to a green light branch of an RGB three-path LED lamp.

It can be seen that, in the LED driving circuit provided in this embodiment, because the electric charges stored in the first capacitor, the second capacitor, and the third capacitor respectively correspond to the branches corresponding to the RGB three-way LED lamps in the multi-lamp system, when the multi-lamp system starts to operate, the first sampling unit, the second sampling unit, and the third sampling unit respectively sample the voltage values of the first capacitor, the second capacitor, and the third capacitor, and feed the minimum voltage value obtained by sampling back to the LED driving chip, in this case, the LED driving chip can send corresponding target control signals to the first switch unit, the second switch unit, and the third switch unit according to the minimum voltage value to control the operation of the multi-lamp system. Obviously, when the LED driving circuit is used to control a multi-lamp system to operate, because the voltages at the two ends of the first capacitor, the second capacitor and the third capacitor cannot change suddenly, when the first switch unit, the second switch unit and the third switch unit receive a target control signal, the first capacitor, the second capacitor and the third capacitor can be controlled by the target control signal to rapidly release the voltage difference generated when the multi-lamp system is switched on, so that the current overshoot phenomenon generated when the LED driving chip drives the multi-lamp system can be avoided.

Based on the above embodiments, this embodiment further describes and optimizes the technical solution, and as a preferred implementation, the first sampling unit and/or the second sampling unit and/or the third sampling unit are arranged in the same or different manners.

In practical application, the first sampling unit, the second sampling unit and the third sampling unit may be set as sampling units with the same circuit structure, or the first sampling unit, the second sampling unit and the third sampling unit may be set as sampling units with different circuit structures. That is, the first sampling unit, the second sampling unit, and the third sampling unit may be configured to sample the voltage values at the two ends of the capacitor.

Obviously, the technical solution provided by this embodiment can make the arrangement of the first sampling unit, the second sampling unit and the third sampling unit more flexible and various.

Based on the above embodiments, the present embodiment further describes and optimizes the technical solution, please refer to fig. 3, and fig. 3 is a structural diagram of another LED driving circuit provided by the embodiment of the present invention. As a preferred embodiment, the first sampling unit includes a first diode D1 and a second diode D2;

the cathode of the first diode D1 is connected to the second terminal of the first capacitor C1, the anode of the first diode D1 is connected to the anode of the second diode D2, and the cathode of the second diode D2 is grounded.

In the present embodiment, a specific arrangement of the sampling units is provided, that is, the first sampling unit is built by using the first diode D1 and the second diode D2. It is conceivable that, by such an arrangement, the building process of the first sampling unit is made simpler and easier. Accordingly, in practical applications, the second sampling unit and the third sampling unit can be constructed by using the diode D3 and the diode D4, respectively.

Based on the above embodiments, the present embodiment further describes and optimizes the technical solution, and as a preferred implementation, the first capacitor C1, the second capacitor C2 and the third capacitor C3 are arranged in the same manner.

Specifically, in the actual operation process, the first capacitor C1, the second capacitor C2 and the third capacitor C3 can be set to be the same type of capacitor, because when the first capacitor C1, the second capacitor C2 and the third capacitor C3 are set to be the same type of capacitor, not only can the difficulty in building the LED driving circuit be reduced, but also the operating condition of the LED driving circuit can be more stable.

As a preferred embodiment, the first capacitor C1 is embodied as an electrolytic capacitor or a tantalum capacitor or a solid state capacitor.

In practical applications, the first capacitor C1 can be configured as an electrolytic capacitor, because the capacitance of the electrolytic capacitor is relatively large and the cost of configuring the electrolytic capacitor is relatively low, when the first capacitor C1 is configured as an electrolytic capacitor, the manufacturing cost required by the LED driving circuit can be relatively reduced.

Or, the first capacitor C1 is set as a tantalum capacitor, because the tantalum capacitor not only has a large capacitance, but also has a small volume, a long service life, high temperature resistance and a good filtering effect, when the first capacitor C1 is set as the tantalum capacitor, the safety of the LED driving circuit in the using process can be relatively improved. In addition, the first capacitor C1 can be set as a solid capacitor, because the solid capacitor can continuously and stably operate under high temperature conditions compared with a general capacitor, and therefore, when the first capacitor C1 is set as a solid capacitor, the stability of the LED driving circuit during operation can be further improved.

Based on the above embodiments, this embodiment further describes and optimizes the technical solution, and as a preferred embodiment, the first switch unit, the second switch unit and the third switch unit are arranged in the same manner.

In this embodiment, the first switch unit, the second switch unit and the third switch unit are provided with the same structural form, because when the first switch unit, the second switch unit and the third switch unit are provided with the same structural form, not only the functional modules of the LED driving circuit can be more orderly, but also the overall stability of the LED driving circuit in the operation process can be improved.

As a preferred embodiment, the first switch unit comprises a first switch tube and a second switch tube;

In this embodiment, a specific setting manner of the first switch unit is provided, that is, in this embodiment, two switch tubes are used to control on or off of one of the RGB three-way LED lamps.

In a preferred embodiment, the first switching tube and the second switching tube are NMOS tubes.

It can be understood that, because the NMOS transistor has low power consumption, strong anti-interference capability, and light weight, when the first switch unit is configured in such a structural form, not only the amount of energy consumption required by the first switch unit in the using process can be reduced, but also the stability of the first switch unit in the operating process can be improved.

Referring to fig. 3, in this embodiment, a first switch unit is built by using a first NOMS transistor N1 and a second NMOS transistor N2, a second switch unit is built by using a third NOMS transistor N3 and a fourth NMOS transistor N4, and a third switch unit is built by using a fifth NOMS transistor N5 and a sixth NMOS transistor N6. Of course, in practical applications, the first switch tube and the second switch tube may also be configured as PMOS tubes or other types of switch tubes, and are not limited herein.

As a preferred embodiment, the LED driving circuit further includes: a first resistor R1 and a fourth capacitor C4;

the first end of the first resistor R1 is configured to receive a target control signal, the second end of the first resistor R1 is respectively connected to the first end of the fourth capacitor C4 and the gate of the second NMOS transistor N2, and the second end of the fourth capacitor C4 is grounded.

In this embodiment, a filter circuit is further disposed at the front end of the first switch unit, that is, the first resistor R1 and the fourth capacitor C4 are used to filter the target control signal received by the first switch unit. Obviously, by such an arrangement, the first switch unit can receive a more stable and reliable target control signal.

In addition, in practical application, a filter circuit may be further disposed at front ends of the second switch unit and the third switch unit, respectively, to filter the target control signals received by the second switch unit and the third switch unit, specifically, see fig. 3. In fig. 3, the second resistor R2 and the fifth capacitor C5 are used for filtering the target control signal received by the second switch unit, and the third resistor R3 and the sixth capacitor C6 are used for filtering the target control signal received by the third switch unit.

In order to make the implementation principle of the LED driving circuit provided by the present invention more clear and obvious to those skilled in the art, the present embodiment is specifically described by an application scenario embodiment. In the present embodiment, the LED driving chip is used as the DLPA3005 for explanation, please refer to fig. 3 and fig. 4, and fig. 4 is a peripheral circuit connected between the LED driving chip DLPA3005 and the multi-lamp system.

In fig. 3, a first end of a first capacitor C1, a first end of a second capacitor C2, and a first end of a third capacitor C3 are respectively connected to a BOOST pin on an LED driver chip DLPA3005, and a second end of the first capacitor C1, a second end of the second capacitor C2, and a second end of the third capacitor C3 are also respectively connected to (i), (ii), and (iii) in fig. 4; in fig. 4, the first, second and third lamps respectively control the red LED lamp, the green LED lamp and the blue LED lamp of the RGB three-way LED lamp of the multi-lamp system. The anode of the first diode D1 and the anode of the third diode D3 in fig. 3 are respectively connected to the VF _ NEG pin of the LED driving chip DLPA3005, and the first end of the first resistor R1, the first end of the second resistor R2 and the first end of the third resistor R3 in fig. 3 are respectively connected to the PWM _ OUT1, PWM _ OUT2 and PWM _ OUT3 pins of the LED driving chip DLPA 3005. PWM _ OUT1, PWM _ OUT2, and PWM _ OUT3 in fig. 4 are connected to the PWM _ OUT1, PWM _ OUT2, and PWM _ OUT3 pins, respectively, on the LED driver chip DLPA3005, and LED _ ISP and LED _ ISN in fig. 4 are connected to the LED _ ISP and LED _ ISN pins, respectively, on the LED driver chip DLPA 3005.

In fig. 4, K1, K2, and K3 are switching tubes, respectively, and the specific model is AON 6382. In practical application, for the display effect of the multi-lamp system, one or more LED lamps may be connected in series to any branch of the three RGB LED lamps to adjust the brightness, hue and saturation of the multi-lamp system. In addition, the LED driving chip may also be configured as TL3744, or other chips of the same type, which are not described herein in detail.

Obviously, when the LED driving chip DLPA3005 is used to control a multi-lamp system to operate, because the voltages at two ends of the first capacitor C1, the second capacitor C2 and the third capacitor C3 cannot change suddenly, when the NMOS transistor N1, N2, N3, N4, N5 and N6 receives a target control signal sent by the LED driving chip DLPA3005, the NMOS transistor N1, N2, N3, N4, N5 and N6 can control the first capacitor C1, the second capacitor C2 and the third capacitor C3 to quickly release the voltage difference generated when the multi-lamp system is switched on through the target control signal, so that the current overshoot phenomenon generated when the LED driving chip DLPA3005 drives the multi-lamp system can be avoided.

Correspondingly, the embodiment of the invention also discloses a projector which comprises the LED driving circuit disclosed in the foregoing.

The projector provided by the embodiment of the invention has the beneficial effects of the LED driving circuit disclosed above.

The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The LED driving circuit and the projector provided by the present invention are described in detail above, and the principle and the implementation of the present invention are explained herein by applying specific examples, and the description of the above examples is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. An LED drive circuit is characterized by being applied to a multi-lamp system, wherein an LED drive chip and RGB three-way LED lamps are arranged in the multi-lamp system, and one or more LED lamps are connected in series on a target circuit of the RGB three-way LED lamps; the method comprises the following steps: the RGB three-way LED lamp driving circuit comprises a first capacitor, a second capacitor, a third capacitor, a first sampling unit, a second sampling unit, a third sampling unit, a first switch unit, a second switch unit and a third switch unit, wherein the first switch unit, the second switch unit and the third switch unit are respectively used for controlling the RGB three-way LED lamp to be independently switched on or switched off according to a target control signal;

2. The LED driving circuit according to claim 1, wherein the first sampling unit and/or the second sampling unit and/or the third sampling unit are arranged in the same or different manners.

3. The LED driving circuit according to claim 1, wherein the first sampling unit comprises a first diode and a second diode;

4. The LED driving circuit according to claim 1, wherein the first capacitor, the second capacitor and the third capacitor are arranged in the same manner.

5. The LED driving circuit according to claim 4, wherein the first capacitor is in particular an electrolytic capacitor or a tantalum capacitor or a solid state capacitor.

6. The LED driving circuit according to claim 1, wherein the first switching unit, the second switching unit and the third switching unit are arranged in the same manner.

7. The LED driving circuit according to claim 6, wherein the first switching unit comprises a first switching tube and a second switching tube;

8. The LED driving circuit according to claim 7, wherein the first switching tube and the second switching tube are NMOS tubes.

9. A projector comprising an LED driving circuit according to any one of claims 1 to 8.