Lighting drive circuit and range hood

Abstract

This application relates to a lighting drive circuit and a range hood. When lighting is needed, a switching circuit connects the power supply to the light source. As the smoke guide plate gradually opens and the light source is powered on, the current flowing through the push rod motor of the smoke guide plate gradually increases, and the voltage parameter sampled by the sampling circuit also gradually increases. The output voltage of the voltage follower circuit decreases as the voltage parameter increases, causing the pull-down circuit to receive the gradually decreasing voltage parameter, thereby gradually reducing the current flowing through the light source, and thus reducing the brightness of the light source. This solution allows for a gradual reduction in the brightness of the light source as the push rod motor drives the smoke guide plate to open. In this way, by reducing the brightness of the light source during the opening of the smoke guide plate, the intensity of light emitted from the smoke guide plate to the human eye is reduced, thereby alleviating the problem of glare.

Description

Technical Field

[0001] This application relates to the field of home appliance technology, and in particular to a lighting drive circuit and a range hood. Background Technology

[0002] With the development of science and technology and the improvement of people's living standards, range hoods have become an indispensable kitchen appliance. Currently, range hoods are generally equipped with lights and smoke guides. The lights provide illumination during cooking, while the smoke guides open and close automatically according to the user's needs to remove smoke.

[0003] However, smoke deflectors usually have strong reflective properties. When the smoke deflector is open, the light emitted by the lighting will be reflected into the user's eyes, resulting in glare. Utility Model Content

[0004] Therefore, it is necessary to propose a lighting drive circuit and a range hood to address the problem of glare from the light when the smoke guide plate of a range hood is opened. This solution reduces the brightness of the light during the opening of the smoke guide plate, thereby alleviating the glare problem.

[0005] This application provides a lighting driving circuit, including: a switching circuit, a lighting lamp, a first resistor, a sampling circuit, a voltage follower circuit, and a pull-down circuit. The switching circuit is connected to a power supply; the lighting lamp is connected to the switching circuit; a first terminal of the first resistor is connected to the lighting lamp, and a second terminal of the first resistor is grounded; the sampling circuit is connected in series with the push rod motor of a range hood, and the sampling circuit is used to collect voltage parameters during the start-up and operation of the push rod motor; the voltage follower circuit is connected to the sampling circuit, and the output voltage of the voltage follower circuit decreases as the voltage parameters increase; the pull-down circuit is connected to the voltage follower circuit, the switching circuit, and the first terminal of the first resistor, and the pull-down circuit is used to reduce the current flowing through the lighting lamp as the output voltage decreases.

[0006] In the aforementioned lighting drive circuit, the power supply, switching circuit, lighting lamp, and first resistor are sequentially connected to form a closed loop. When lighting is required, the switching circuit is activated to connect the power supply and the lighting lamp. A sampling circuit, a voltage follower circuit, and a pull-down circuit are also included. As the smoke guide plate gradually opens and the lighting lamp is powered on, the current flowing through the push rod motor of the smoke guide plate gradually increases, and the voltage parameter sampled by the sampling circuit also gradually increases. The output voltage of the voltage follower circuit decreases as the voltage parameter increases, causing the pull-down circuit to receive the gradually decreasing voltage parameter, thereby gradually reducing the current flowing through the lighting lamp, and thus reducing the brightness of the lighting lamp. This design allows for a gradual reduction in the brightness of the lighting lamp as the push rod motor drives the smoke guide plate to open. In this way, by reducing the brightness of the lighting lamp during the opening of the smoke guide plate, the intensity of light emitted from the smoke guide plate to the human eye is reduced, thereby alleviating the problem of glare.

[0007] In one embodiment, the lighting driving circuit further includes a controller, the switching circuit and the sampling circuit are respectively connected to the controller, and the controller is used to control the start and stop of the switching circuit and the sampling circuit.

[0008] The above scheme configures the sampling circuit and the switching circuit as controllable circuits, and controls the start and stop of both through the controller, thereby improving the automation level of the driving lighting circuit.

[0009] In one embodiment, the sampling circuit includes a first switching device and a second resistor. The input terminal of the first switching device is connected to the push rod motor, the output terminal of the first switching device is connected to the first terminal of the second resistor, the second terminal of the second resistor is grounded, the control terminal of the first switching device is connected to the controller, and the first terminal of the second resistor is also connected to the voltage follower circuit.

[0010] The above scheme uses a first switching device and a second resistor to build the sampling circuit. The start and stop of the sampling circuit are controlled by switching the first switching device on and off. The circuit structure is simple and effectively saves circuit costs.

[0011] In one embodiment, the voltage follower circuit includes a third resistor, a fourth resistor, and a differential amplifier. The first end of the third resistor is connected to the sampling circuit, the second end of the third resistor is connected to the inverting input of the differential amplifier, the non-inverting input of the differential amplifier is connected to a reference source, the output of the differential amplifier is connected to the first end of the fourth resistor and the pull-down circuit, and the second end of the fourth resistor is connected to the inverting input of the differential amplifier.

[0012] The above solution uses the differential amplifier as a subtractor by controlling its gain to 1. This eliminates the need for common-mode rejection, allowing the output voltage to decrease as the voltage parameter increases, thus effectively reducing the circuit size.

[0013] In one embodiment, the voltage follower circuit further includes a fifth resistor and a sixth resistor, the first end of the fifth resistor and the first end of the sixth resistor being connected to the positive input terminal of the differential amplifier, the second end of the fifth resistor being connected to the reference source, and the second end of the sixth resistor being grounded.

[0014] The above scheme connects a fifth resistor and a sixth resistor between the positive input terminal of the differential amplifier and the reference source, thereby providing a suitable reference voltage for the positive input terminal of the differential amplifier and improving the operational reliability of the voltage follower circuit.

[0015] In one embodiment, the pull-down circuit includes an error amplifier and a second switching device. The inverting input of the error amplifier is connected to the voltage follower circuit, the non-inverting input of the error amplifier is connected to the first terminal of the first resistor, the output of the error amplifier is connected to the control terminal of the second switching device, the input of the second switching device is connected to the switching circuit, and the output of the second switching device is grounded.

[0016] The above scheme controls the error amplifier to operate in a negative feedback closed-loop system, making the voltage at its positive input terminal consistent with the voltage at its inverting input terminal. In this way, as the output voltage decreases, the voltage across the first resistor also decreases synchronously, ultimately reducing the current flowing through the first resistor and the lighting lamp. This has good voltage following characteristics and improves the voltage pull-down effect.

[0017] In one embodiment, the pull-down circuit further includes a current limiting circuit, and the inverting input of the error amplifier is connected to the voltage follower circuit through the current limiting circuit.

[0018] The above scheme also includes a current-limiting resistor between the error amplifier and the voltage follower circuit to ensure the safe operation of the error amplifier.

[0019] In one embodiment, the switching circuit includes a third switching device, a fourth switching device, a seventh resistor, and an eighth resistor. The input terminal of the third switching device is connected to a power supply. The output terminal of the third switching device is connected to the first terminal of the seventh resistor and the first terminal of the eighth resistor. The second terminal of the seventh resistor is connected to the input terminal of the fourth switching device. The output terminal of the fourth switching device is connected to the lighting lamp. The second terminal of the eighth resistor is connected to the control terminal of the fourth switching device and the pull-down circuit. The control terminal of the third switching device is connected to the controller.

[0020] The above scheme uses a third switching device, a fourth switching device, a seventh resistor, and an eighth resistor to build a switching circuit, so that when there is a need for lighting, the controller can realize the start and stop control of lighting, which has a high degree of lighting controllability.

[0021] In one embodiment, the lighting lamp is a light-emitting diode.

[0022] The above solution, which uses light-emitting diodes as the lighting for the range hood, has the advantages of high luminous efficiency and energy saving and environmental protection.

[0023] A range hood includes a smoke guide plate, a push rod motor, and the aforementioned lighting drive circuit, wherein the push rod motor is connected to the smoke guide plate. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the lighting driving circuit structure in one embodiment of this application;

[0026] Figure 2 This is a schematic diagram of the lighting drive circuit structure in another embodiment of this application;

[0027] Figure 3 This is a schematic diagram of the lighting driving circuit structure in another embodiment of this application;

[0028] Figure 4 This is a schematic diagram of the lighting driving circuit structure in another embodiment of this application;

[0029] Figure 5 This is a schematic diagram of the lighting drive circuit structure in another embodiment of this application;

[0030] Figure 6 This is a schematic diagram of the lighting drive circuit structure in another embodiment of this application.

[0031] Explanation of reference numerals in the attached figures:

[0032] 11-Switching circuit, 12-Sampling circuit, 13-Voltage follower circuit, 14-Pull-down circuit, 15-Controller; R1-First resistor, R2-Second resistor, R3-Third resistor, R4-Fourth resistor, R5-Fifth resistor, R6-Sixth resistor, R7-Seventh resistor, R8-Eighth resistor; Q1-First switching device, Q2-Second switching device, Q3-Third switching device, Q4-Fourth switching device; D-Lighting lamp, 20-Follow rod motor, 141-Current limiting circuit; B1-Differential amplifier, B2-Error amplifier. Detailed Implementation

[0033] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0036] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0037] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0038] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0039] Please see Figure 1 This application provides a lighting driving circuit, including: a switching circuit 11, a lighting lamp D, a first resistor R1, a sampling circuit 12, a voltage follower circuit 13, and a pull-down circuit 14. The switching circuit 11 is connected to a power supply (i.e., VCC2 shown in the figure); the lighting lamp D is connected to the switching circuit 11; the first end of the first resistor R1 is connected to the lighting lamp D, and the second end of the first resistor R1 is grounded; the sampling circuit 12 is connected in series with the push rod motor 20 of the range hood (connected to the power supply VCC1), and the sampling circuit 12 is used to collect the voltage parameters during the start-up and operation of the push rod motor 20; the voltage follower circuit 13 is connected to the sampling circuit 12, and the output voltage of the voltage follower circuit 13 decreases as the voltage parameters increase; the pull-down circuit 14 is connected to the voltage follower circuit 13, the switching circuit 11, and the first end of the first resistor R1, and the pull-down circuit 14 is used to reduce the current flowing through the lighting lamp D as the output voltage decreases.

[0040] Specifically, the switching circuit 11 controls the connection or disconnection of the power supply and the lighting lamp D by turning them on and off; the lighting lamp D is the device that provides illumination; the sampling circuit 12 is the circuit that collects the voltage of the push rod motor 20; the push rod motor 20 is the motor device that can convert rotary motion into linear reciprocating motion to drive the smoke guide plate to open and close. The voltage follower circuit 13 is the circuit whose output voltage can change with the change of input voltage; the pull-down circuit 14 is the circuit that can reduce the current flowing through the lighting lamp D according to the change of its internal voltage.

[0041] It should be noted that the type of switch circuit 11 is not unique. It can be a manual switch circuit 11, that is, a circuit that realizes the switching function through user operation, or an automatic switch circuit 11, that is, a circuit that realizes the switching function under the action of a driving device. The specific type is not limited.

[0042] For example, in one embodiment, the switch circuit 11 includes a mechanical switch, which the user manually presses to control the on / off state of the switch circuit 11; in another embodiment, the switch circuit 11 may also include a touch switch, which the user touches to control the on / off state.

[0043] The type of sampling circuit 12 is not unique; it only needs to convert the current change of the push rod motor 20 into a voltage change and transmit it to the voltage follower circuit 13. No specific limitation is made. The line between the sampling circuit 12 and the push rod motor 20 can be normally closed, or it can be controlled to be on or off according to actual needs. The specific choice depends on the actual requirements. The structure of the sampling circuit 12 will also differ under different functional requirements, and no limitation is made here.

[0044] In practical scenarios, if lighting is needed, the required current can be supplied to the lighting lamp D by turning on the switch circuit 11 to activate the lighting function; if there is no lighting need, the switch circuit 11 can be turned off. If lighting is needed during the operation of the smoke guide plate, the light can easily shine into people's eyes due to the change in the angle of the smoke guide plate, so brightness adjustment is required. Specifically, at this time, the push rod motor 20 starts running, and the sampling circuit 12 will collect the changing voltage parameters based on the current change of the push rod motor 20. As the smoke guide plate gradually opens, the current of the push rod motor 20 gradually increases, and the collected voltage parameters also gradually increase. The output voltage of the voltage follower circuit 13 decreases as the voltage parameters increase, and this gradually decreasing output voltage is sent to the pull-down circuit 14. The pull-down circuit 14 responds to the decrease in output voltage by pulling down the voltage across the first resistor R1, thereby reducing the current flowing through the first resistor R1. Since the lighting lamp D is connected in series with the first resistor R1, the current flowing through the lighting lamp D will decrease accordingly, eventually causing the brightness of the lighting lamp D to gradually weaken. When the smoke guide plate is fully open, the lighting lamp D operates at the lowest brightness.

[0045] In the aforementioned lighting drive circuit, the power supply, switching circuit 11, lighting lamp D, and first resistor R1 are sequentially connected to form a closed loop. When lighting is required, the switching circuit 11 is turned on to connect the power supply to the lighting lamp D. A sampling circuit 12, a voltage follower circuit 13, and a pull-down circuit 14 are also included. As the smoke guide plate gradually opens and the lighting lamp D is powered on, the current flowing through the push rod motor 20 of the smoke guide plate gradually increases, and the voltage parameter sampled by the sampling circuit 12 also gradually increases. The output voltage of the voltage follower circuit 13 decreases as the voltage parameter increases, causing the pull-down circuit 14 to receive the gradually decreasing voltage parameter, thereby gradually reducing the current flowing through the lighting lamp D, and thus reducing the brightness of the lighting lamp D. Through this scheme, the brightness of the lighting lamp D can be gradually reduced as the push rod motor 20 drives the smoke guide plate to open. In this way, by reducing the brightness of the lighting lamp D during the opening of the smoke guide plate, the intensity of light emitted from the smoke guide plate to the human eye is reduced, thereby alleviating the problem of glare.

[0046] Please see Figure 2In one embodiment, the lighting driving circuit further includes a controller 15, with the switching circuit 11 and the sampling circuit 12 respectively connected to the controller 15. The controller 15 is used to control the start and stop of the switching circuit 11 and the sampling circuit 12.

[0047] Specifically, in this embodiment, the switching circuit 11 is a controllable switching circuit 11, and the sampling circuit 12 is also a circuit with controllable sampling operation. Therefore, a controller 15 is also provided in the lighting drive circuit to control the start and stop of the switching circuit 11 and the sampling circuit 12.

[0048] Specifically, when controller 15 detects a lighting requirement (e.g., receiving a user-sent command or detecting insufficient ambient light in the range hood's operating environment), it sends a control signal to switch circuit 11 to activate the lighting. If no lighting requirement is detected, no control signal is sent, and switch circuit 11 remains off. If the smoke guide plate is activated and the lighting D needs to be turned on, both sampling circuit 12 and switch circuit 11 are activated simultaneously. If only the smoke guide plate is activated, neither sampling circuit 12 nor switch circuit 11 needs to be activated.

[0049] It should be noted that the type of switching device is not unique. It can be any device with control function inside the range hood, or it can be an independently set controller. There is no specific limitation.

[0050] The above scheme configures the sampling circuit 12 and the switching circuit 11 as controllable circuits, and controls their start and stop through the controller 15, thereby improving the automation level of the driving lighting circuit.

[0051] Please see Figure 3 In one embodiment, the sampling circuit 12 includes a first switching device Q1 and a second resistor R2. The input terminal of the first switching device Q1 is connected to the push rod motor 20, the output terminal of the first switching device Q1 is connected to the first terminal of the second resistor R2, the second terminal of the second resistor R2 is grounded, the control terminal of the first switching device Q1 (through the port P1 shown in the figure) is connected to the controller 15 (not shown in the figure), and the first terminal of the second resistor R2 is also connected to the voltage follower circuit 13.

[0052] Specifically, in this embodiment, the sampling circuit 12 includes a first switching device Q1 and a second resistor R2 connected in series with the push rod motor 20. The control terminal of the second switching device is connected to the controller 15, and the switching is realized under the control of the controller 15. The type of the first switching device Q1 is not unique; it can be a MOSFET (Metal-O-Semiconductor Field-Effect Transistor), a transistor, or an insulated-gate bipolar transistor, etc., and is not specifically limited.

[0053] In the above scheme, the sampling circuit 12 is built using the first switching device Q1 and the second resistor R2. The start and stop control of the sampling circuit 12 is realized by switching the first switching device Q1 on and off. The circuit structure is simple and effectively saves circuit costs.

[0054] Please see Figure 4 In one embodiment, the voltage follower circuit 13 includes a third resistor R3, a fourth resistor R4, and a differential amplifier B1. The first end of the third resistor R3 is connected to the sampling circuit 12, the second end of the third resistor R3 is connected to the inverting input of the differential amplifier B1, the non-inverting input of the differential amplifier B1 is connected to the reference source (i.e., the +5V power supply shown in the figure), the output of the differential amplifier B1 is connected to the first end of the fourth resistor R4 and the pull-down circuit 14, and the second end of the fourth resistor R4 is connected to the inverting input of the differential amplifier B1.

[0055] Specifically, in this embodiment, a subtractor is constructed using a differential amplifier B1, causing its output voltage to decrease as the input voltage increases, thus achieving a voltage follower function. Specifically, the gain of the differential amplifier B1 is configured to 1. The positive input terminal of the differential amplifier B1 is connected to a reference source with a fixed input voltage, while the inverting input terminal of the differential amplifier B1 is connected to the sampling circuit 12. The output voltage of the differential amplifier B1 is the difference between the two input voltages. As the voltage parameter output by the sampling circuit 12 increases, the output voltage of the differential amplifier B1 gradually decreases.

[0056] It is understood that in other embodiments, other types of circuits or devices may be used as voltage follower circuit 13, such as a subtractor, as long as the output voltage can decrease as the input voltage increases.

[0057] The above solution uses differential amplifier B1 as a subtractor by controlling its gain to 1. This eliminates the need for common-mode rejection, allowing the output voltage to decrease as the voltage parameter increases, thus effectively reducing the circuit size.

[0058] Please continue reading. Figure 4 In one embodiment, the voltage follower circuit 13 further includes a fifth resistor R5 and a sixth resistor R6. The first end of the fifth resistor R5 and the first end of the sixth resistor R6 are respectively connected to the positive input terminal of the differential amplifier B1, the second end of the fifth resistor R5 is connected to the reference source, and the second end of the sixth resistor R6 is grounded.

[0059] Specifically, in this embodiment, a voltage divider circuit consisting of a fifth resistor R5 and a sixth resistor R6 is configured at the positive input terminal of the differential amplifier B1 to enable the connection of a reference source and ensure the stability of the input voltage at the positive input terminal of the differential amplifier B1.

[0060] The above scheme connects a fifth resistor R5 and a sixth resistor R6 between the positive input terminal of the differential amplifier B1 and the reference source, thereby providing a suitable reference voltage for the positive input terminal of the differential amplifier B1 and improving the operational reliability of the voltage follower circuit 13.

[0061] Please see Figure 5 In one embodiment, the pull-down circuit 14 includes an error amplifier B2 and a second switching device Q2. The inverting input of the error amplifier B2 is connected to the voltage follower circuit 13, the non-inverting input of the error amplifier B2 is connected to the first end of the first resistor R1, the output of the error amplifier B2 is connected to the control terminal of the second switching device Q2, the input of the second switching device Q2 is connected to the switching circuit 11, and the output of the second switching device Q2 is grounded.

[0062] Specifically, in this embodiment, a pull-down circuit 14 is constructed using error amplifier B2. Utilizing the discontinuous characteristic of error amplifier B2, a negative feedback adjustment mechanism is configured to ensure that the input voltage at its positive input terminal is the same as the input voltage at its inverting input terminal. Thus, when the output voltage is connected to the inverting input terminal of error amplifier B2, as the output voltage decreases, the voltage at the inverting input terminal of error amplifier B2 also decreases, consequently causing a decrease in the voltage at the positive input terminal of error amplifier B2. This results in a decrease in the voltage across the first resistor R1. With the resistance of the first resistor R1 remaining constant, the current flowing through it also decreases, thereby reducing the brightness of the lighting lamp D. The second switching device Q2 is activated under the output control of error amplifier B2, forming a closed loop and ensuring the stable operation of the lighting drive circuit.

[0063] The above scheme controls the error amplifier B2 to operate in a negative feedback closed-loop system, making the voltage at its positive input terminal consistent with the voltage at its inverting input terminal. In this way, as the output voltage decreases, the voltage across the first resistor R1 also decreases synchronously, ultimately reducing the current flowing through the first resistor R1 and the lighting lamp D. This scheme has good voltage following characteristics and improves the voltage pull-down effect.

[0064] Please continue reading. Figure 5 In one embodiment, the pull-down circuit 14 further includes a current limiting circuit 141, through which the inverting input of the error amplifier B2 is connected to the voltage follower circuit 13.

[0065] Specifically, the current limiting circuit 141, which limits the magnitude of the current flowing through it, is not unique in type. It can be a current limiting resistor or other types, such as a diode current limiting circuit 141, etc., without limitation. For ease of understanding, the current limiting circuit 141 in the following embodiments can be considered to include a current limiting resistor. Specifically, it can be a single resistor or a component formed by multiple resistors connected in series and / or in parallel, without limitation.

[0066] In the above scheme, a current-limiting resistor is also set between the error amplifier B2 and the voltage follower circuit 13 to ensure the safe operation of the error amplifier B2.

[0067] Please see Figure 6 In one embodiment, the switching circuit 11 includes a third switching device Q3, a fourth switching device Q4, a seventh resistor R7, and an eighth resistor R8. The input terminal of the third switching device Q3 is connected to the power supply, and the output terminal of the third switching device Q3 is connected to the first terminal of the seventh resistor R7 and the first terminal of the eighth resistor R8. The second terminal of the seventh resistor R7 is connected to the input terminal of the fourth switching device Q4, and the output terminal of the fourth switching device Q4 is connected to the lighting lamp D. The second terminal of the eighth resistor R8 is connected to the control terminal of the fourth switching device Q4 and the pull-down circuit 14. The control terminal of the third switching device Q3 (through the illustrated P2 port) is connected to the controller 15 (not shown).

[0068] Specifically, the switching circuit 11 in this embodiment includes a cascaded third switching device Q3 and a fourth switching device Q4, and resistors are respectively configured at the input terminal and the control terminal of the fourth switching device Q4 to ensure the operational safety of the switching circuit 11.

[0069] It should be noted that the types of the third switching device Q3 and the fourth switching device Q4 are not unique; they can be transistors or MOSFETs, etc., and are not limited here.

[0070] The above scheme uses a third switching device Q3, a fourth switching device Q4, a seventh resistor R7, and an eighth resistor R8 to build a switching circuit 11, so that when there is a lighting demand, the controller 15 can realize the lighting start and stop control, which has a high degree of lighting controllability.

[0071] In one embodiment, the lighting lamp D is a light-emitting diode (LED). A light-emitting diode (LED) is a device that emits light through the recombination of electrons and holes, converting electrical energy into light energy. In other embodiments, organic light-emitting diodes (OLEDs), fluorescent lamps, incandescent lamps, etc., can also be used as the lighting lamp D; the specific method is not limited.

[0072] The above solution, which uses LEDs as the lighting lamp D of the range hood, has the advantages of high luminous efficiency and energy saving and environmental protection.

[0073] This application also provides a range hood, including a smoke guide plate, a push rod motor 20 and the above-mentioned lighting drive circuit, wherein the push rod motor 20 is connected to the smoke guide plate.

[0074] Specifically, the structure and operating principle of the lighting drive circuit are as shown in the above embodiments and accompanying drawings, and will not be repeated here. In the above-mentioned range hood, the power supply, switch circuit 11, lighting lamp D, and first resistor R1 are sequentially connected to form a closed loop. When lighting is required, the switch circuit 11 is turned on to connect the power supply to the lighting lamp D. A sampling circuit 12, a voltage follower circuit 13, and a pull-down circuit 14 are also provided. As the smoke guide plate gradually opens and the lighting lamp D is powered on, the current flowing through the push rod motor 20 of the smoke guide plate gradually increases, and the voltage parameter sampled by the sampling circuit 12 also gradually increases. The output voltage of the voltage follower circuit 13 decreases as the voltage parameter increases, causing the pull-down circuit 14 to receive the gradually decreasing voltage parameter, thereby gradually reducing the current flowing through the lighting lamp D, i.e., reducing the brightness of the lighting lamp D. Through this scheme, the brightness of the lighting lamp D can be gradually reduced as the push rod motor 20 drives the smoke guide plate to open. In this way, by reducing the brightness of the light lamp D during the opening of the smoke guide plate, the intensity of light emitted from the smoke guide plate to the human eye is reduced, thereby alleviating the problem of glare.

[0075] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0076] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An illumination drive circuit, characterized by, include: Switching circuit, connected to power supply; Lighting lamp, connected to the switching circuit; A first resistor, with its first end connected to the lighting lamp and its second end grounded; A sampling circuit is connected in series with the push rod motor of the range hood. The sampling circuit is used to collect voltage parameters during the start-up and operation of the push rod motor. A voltage follower circuit is connected to the sampling circuit, and the output voltage of the voltage follower circuit decreases as the voltage parameter increases; A pull-down circuit is connected to the voltage follower circuit, the switching circuit, and the first terminal of the first resistor. The pull-down circuit is used to follow the decrease of the output voltage and pull down the current flowing through the lighting lamp.

2. The lighting drive circuit of claim 1, wherein, The lighting drive circuit also includes a controller, and the switching circuit and the sampling circuit are respectively connected to the controller. The controller is used to control the start and stop of the switching circuit and the sampling circuit.

3. The lighting drive circuit of claim 2, wherein, The sampling circuit includes a first switching device and a second resistor. The input terminal of the first switching device is connected to the push rod motor, the output terminal of the first switching device is connected to the first terminal of the second resistor, the second terminal of the second resistor is grounded, the control terminal of the first switching device is connected to the controller, and the first terminal of the second resistor is also connected to the voltage follower circuit.

4. The lighting driving circuit according to any one of claims 1 to 3, characterized by The voltage follower circuit includes a third resistor, a fourth resistor, and a differential amplifier. The first end of the third resistor is connected to the sampling circuit, the second end of the third resistor is connected to the inverting input of the differential amplifier, the non-inverting input of the differential amplifier is connected to a reference source, the output of the differential amplifier is connected to the first end of the fourth resistor and the pull-down circuit, and the second end of the fourth resistor is connected to the inverting input of the differential amplifier.

5. The lighting driving circuit according to claim 4, characterized in that, The voltage follower circuit further includes a fifth resistor and a sixth resistor. The first end of the fifth resistor and the first end of the sixth resistor are respectively connected to the positive input terminal of the differential amplifier. The second end of the fifth resistor is connected to the reference source, and the second end of the sixth resistor is grounded.

6. The lighting driving circuit according to any one of claims 1 to 3, characterized by The pull-down circuit includes an error amplifier and a second switching device. The inverting input of the error amplifier is connected to the voltage follower circuit, the non-inverting input of the error amplifier is connected to the first end of the first resistor, the output of the error amplifier is connected to the control terminal of the second switching device, the input of the second switching device is connected to the switching circuit, and the output of the second switching device is grounded.

7. The lighting driving circuit according to claim 6, characterized in that, The pull-down circuit also includes a current limiting circuit, and the inverting input of the error amplifier is connected to the voltage follower circuit through the current limiting circuit.

8. The lighting driving circuit according to claim 2 or 3, characterized in that, The switching circuit includes a third switching device, a fourth switching device, a seventh resistor, and an eighth resistor. The input terminal of the third switching device is connected to the power supply. The output terminal of the third switching device is connected to the first terminal of the seventh resistor and the first terminal of the eighth resistor. The second terminal of the seventh resistor is connected to the input terminal of the fourth switching device. The output terminal of the fourth switching device is connected to the lighting lamp. The second terminal of the eighth resistor is connected to the control terminal of the fourth switching device and the pull-down circuit. The control terminal of the third switching device is connected to the controller.

9. The lighting driving circuit according to any one of claims 1 to 3, characterized by The lighting is a light-emitting diode (LED).

10. A range hood characterized by, It includes a smoke guide plate, a push rod motor, and a lighting drive circuit as described in any one of claims 1-9, wherein the push rod motor is connected to the smoke guide plate.

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