Adaptive control circuit and control chip of a lamp

Abstract

This application provides an adaptive control circuit and control chip for a lamp, wherein the lamp's resistance changes with temperature. The adaptive control circuit includes a control circuit and a switching circuit; the control circuit is connected to the switching circuit; the control circuit is used to output different adaptive switching frequencies; wherein the adaptive switching frequencies are used to heat the lamp's initial resistance to its operating resistance; the switching circuit is used to control the lamp's operating state. This application adaptively controls the lamp based on different target input voltages of the switching circuit, ensuring the lamp's safety.

Description

Technical Field

[0001] This application relates to the field of lighting control technology, and more specifically, to an adaptive control circuit and control chip for a lamp. Background Technology

[0002] Most current lamps use tungsten filaments as the light-emitting component. Due to the metallic properties of tungsten filaments, their resistance changes with temperature. Commonly used lamps include incandescent lamps and halogen lamps. This property of changing resistance presents new challenges for lamp control.

[0003] For example, current halogen lamp controls are based on fixed switching frequencies, which can easily cause the lamp to burn out during cold starts. Furthermore, the input voltage of a halogen lamp can change depending on the usage scenario. If only one overcurrent protection voltage is used, the lamp can also burn out when the input voltage changes. Utility Model Content

[0004] In view of this, the purpose of this application is to provide an adaptive control circuit and control chip for a lamp to overcome the problems in the prior art.

[0005] In a first aspect, embodiments of this application provide an adaptive control circuit for a lamp, wherein the resistance of the lamp changes with temperature, and the adaptive control circuit includes: a control circuit and a switching circuit; the control circuit is connected to the switching circuit. The control circuit is used to output different adaptive switching frequencies; wherein, the adaptive switching frequency is used to heat the initial resistance of the lamp to the working resistance. The switching circuit is used to control the working state of the lamp.

[0006] In some technical solutions of this application, the control circuit includes: a preheating circuit and a frequency modulation circuit; The frequency modulation circuit is used to output an adaptive switching frequency corresponding to the target input voltage of the switching circuit; The preheating circuit is used to heat the initial resistance of the lamp to the operating resistance when the voltage is not within the target voltage range.

[0007] In some technical solutions of this application, the above-mentioned frequency modulation circuit includes a first conversion unit, a second conversion unit, and a third conversion unit; The first conversion unit is used to receive the target input voltage of the switching circuit and output a controlled conversion current; The second conversion unit is used to receive the controlled conversion current and output the target voltage threshold. The third conversion unit is used to output an adaptive switching frequency corresponding to the target voltage threshold.

[0008] In some technical solutions of this application, the above-mentioned control circuit is used to increase the initial switching frequency of the switching circuit to an adaptive switching frequency. The switching circuit is used to control the lamp to heat its initial resistance to its operating resistance at the adaptive switching frequency.

[0009] In some technical solutions of this application, the aforementioned adaptive switching frequency includes a first switching frequency and a second switching frequency; the first switching frequency is different from the second switching frequency. The control circuit is used to receive the first input voltage of the switching circuit and output the first switching frequency; The control circuit is used to receive the second input voltage of the switching circuit and output the second switching frequency; the first input voltage is different from the second input voltage.

[0010] In some technical solutions of this application, the first conversion unit includes a first comparator, a first MOSFET, a second MOSFET, a fourth MOSFET, an eighth MOSFET, and a first resistor; The second conversion unit includes: a second comparator, a third MOSFET, a fifth MOSFET, a sixth MOSFET, and a second resistor; The third conversion unit includes a third comparator, a third resistor, a seventh MOS transistor, a ninth MOS transistor, a tenth MOS transistor, a capacitor, and a fourth comparator.

[0011] In some technical solutions of this application, the aforementioned switching circuit is connected to the lamp via a sampling wire containing a preset resistance value; the monitoring voltage is the voltage of the sampling wire; The preheating circuit is used to detect the voltage of the sampling wire.

[0012] In some technical solutions of this application, the preheating circuit includes: a comparison module, a trigger module, and an oscillation module; The comparison module is used to compare the monitored voltage with the voltage threshold corresponding to the target voltage range and output an enable signal; The trigger module is used to receive the enable signal and the adaptive switching frequency, and output the adaptive switching frequency when the enable signal is enabled. The oscillation module is used to output the adaptive switching frequency.

[0013] In some technical solutions of this application, the aforementioned switching circuit includes a switching MOSFET; The preheating circuit is used to control the switching of the MOSFET to heat the initial resistance of the lamp.

[0014] Secondly, this application provides a control chip, including the aforementioned adaptive control circuit, for controlling a lamp.

[0015] The technical solutions provided by the embodiments of this application may include the following beneficial effects: This application provides an adaptive control circuit and control chip for a lamp, wherein the resistance of the lamp changes with temperature. The adaptive control circuit includes a control circuit and a switching circuit; the control circuit is connected to the switching circuit; the control circuit is used to output different adaptive switching frequencies; wherein the adaptive switching frequencies are used to heat the initial resistance of the lamp to its operating resistance; the switching circuit is used to control the operating state of the lamp. This application adaptively controls the lamp based on different target input voltages of the switching circuit, ensuring the safety of the lamp.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of an adaptive control circuit for a lamp provided in an embodiment of this application is shown; Figure 2 A schematic diagram of a control circuit provided in an embodiment of this application is shown; Figure 3 A schematic diagram of a frequency modulation circuit provided in an embodiment of this application is shown; Figure 4 A schematic diagram of a preheating circuit provided in an embodiment of this application is shown; Figure 5 A schematic diagram illustrating the monitoring voltage and voltage threshold changes provided in an embodiment of this application; Figure 6 This is a schematic diagram showing the connection between an adaptive control circuit for a lamp and a lamp, as provided in an embodiment of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0020] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0022] Most current lamps use tungsten filaments as the light-emitting component. Due to the metallic properties of tungsten filaments, their resistance changes with temperature. Commonly used lamps include incandescent lamps and halogen lamps. This property of changing resistance presents new challenges for lamp control.

[0023] For example, current halogen lamp controls are based on fixed switching frequencies, which can easily cause the lamp to burn out during cold starts. Furthermore, the input voltage of a halogen lamp can change depending on the usage scenario. If only one overcurrent protection voltage is used, the lamp can also burn out when the input voltage changes.

[0024] Based on this, embodiments of this application provide an adaptive control circuit and control chip for a lamp. Some implementation methods of this application are described in detail below. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0025] Figure 1This illustration shows a schematic diagram of an adaptive control circuit for a lamp according to an embodiment of this application. It should be noted that in this embodiment, the resistance of the lamp or its light-emitting component changes with temperature; that is, when the light-emitting component is a metal filament, the filament can be a tungsten filament lamp. The adaptive control circuit in this embodiment is not applicable to lamps where the resistance of the lamp or its light-emitting component remains constant (or changes only slightly; here, "small change" can be measured by a specific resistance change threshold), such as fluorescent lamps, sodium lamps, and LED lamps.

[0026] For lamps whose light-emitting component resistance changes with temperature, this application provides an adaptive control circuit. The control circuit includes a switching circuit 200 and a control circuit 100. The switching circuit 200 controls the lamp's operating state (on and off state), and the control circuit 100 outputs different adaptive switching frequencies to control the lamp's resistance value. This avoids the lamp burning out due to low resistance (large current) when the switching circuit 200 controls the lamp to be on under different input voltages.

[0027] In an optional implementation, due to the resistance characteristics of the lamp or light-emitting component (which change with temperature, generally increasing with rising temperature), the control circuit 100 in this embodiment controls the lamp resistance by increasing the lamp temperature, thereby increasing the lamp's resistance value. Various methods are used to increase the lamp temperature, such as heating. Considering safety and production costs, this embodiment adopts a method of increasing the lamp temperature by switching the lamp at a high frequency (relative to the initial switching frequency, which is the frequency used to control the lamp to operate normally).

[0028] When using a high-frequency switching method to increase the lamp temperature, considering the change in the input voltage of the switching circuit, this embodiment outputs different adaptive switching frequencies for different input voltages, and then increases the switching frequency of the switching circuit 200 from the initial switching frequency to the adaptive switching frequency. The specific value of the adaptive switching frequency can be set according to the lamp's initial resistance value. For example, when the initial resistance value is large, the adaptive switching frequency can be set smaller, and vice versa. After the control circuit 100 outputs the adaptive switching frequency to the switching circuit 200, the switching circuit 200 controls the lamp to turn on and off at the adaptive switching frequency. Each time the lamp is turned on and off, its temperature increases. When the lamp temperature reaches a preset temperature threshold, the lamp's resistance reaches its operating resistance. Due to the increase in lamp resistance, the input voltage remains constant, and the current flowing through the lamp is smaller than when the resistance is not increased, thus preventing the lamp from burning out. For example, when the control circuit 100 receives the first input voltage from the switching circuit 200, it outputs the first switching frequency; when the control circuit 100 receives the second input voltage from the switching circuit 200, it outputs the second switching frequency; the first input voltage and the second input voltage are different, and the first switching frequency and the second switching frequency are different.

[0029] In an alternative implementation, such as Figure 2 As shown, the control circuit in this embodiment includes a preheating circuit 101 and a frequency modulation circuit 102. The frequency modulation circuit 102 receives the target input voltage of the switching circuit and outputs an adaptive switching frequency corresponding to the target input voltage of the switching circuit 200; the preheating circuit 101 detects the monitoring voltage. If the monitoring voltage is not within the target voltage range, the initial resistance of the lamp is heated to the operating resistance.

[0030] In an alternative implementation, such as Figure 3 As shown, the frequency modulation circuit 102 includes a first conversion unit, a second conversion unit, and a third conversion unit. The first conversion unit receives the target input voltage of the switching circuit and outputs a controlled conversion current. The second conversion unit receives the controlled conversion current and outputs a target voltage range (target voltage threshold). The third conversion unit outputs an adaptive switching frequency corresponding to the target voltage threshold. The first conversion unit includes a first comparator, a first MOSFET, a second MOSFET, a fourth MOSFET, an eighth MOSFET, and a first resistor. The target input voltage Vin is connected to one input terminal of Buffer1 (the first comparator) after passing through the first resistor R1. The reference voltage Vref1 is connected to the other input terminal of Buffer1. The output terminal of Buffer1 is connected to the gate of the eighth MOSFET M8, and the current I... The current flows into the drain of the eighth MOSFET M8, exits from the source of M8, and flows to the drain of M2. M2 and M2 form a current mirror. The gate of M2 is connected to the gate and drain of M1. The source of M1 is grounded. The source of M2 is connected to the drain of M1. The current replicated by M2 flows out of its drain and into the source of M4. The gate of M4 is associated with the control node of the first conversion unit. The current flows out of the drain of M4 and into the second conversion unit. The second conversion unit includes: a second comparator, a third MOSFET, a fifth MOSFET, a sixth MOSFET, and a second resistor. The controlled output current of the first conversion unit is connected to the source of the fifth MOSFET M5. M5 and the sixth MOSFET M6 form a current mirror. The gate of M5 is connected to its own drain and the gate of M6. The current flows out of the drain of M5 and is replicated by M6. The source of M6 is connected to a high potential, and its drain is connected to one end of the second resistor R2. The other end of R2 is connected to one input of the second comparator Buffer2. The other input of Buffer2 is connected to... The output of Buffer2 serves as the output of the second conversion unit, outputting voltage V. OCP .

[0031] V OCP The specific value is:

[0032]

[0033]

[0034]

[0035] The third conversion unit includes a third comparator, a third resistor, a seventh MOSFET, a ninth MOSFET, a tenth MOSFET, a capacitor, and a fourth comparator. The output of Buffer3 is connected to the gate of the tenth MOSFET M10. M10 is connected to one end of the third resistor R3, and the other end of R3 is grounded. The ninth MOSFET M9 and the seventh MOSFET M7 form a current mirror. The source of M7 is connected to a high potential, and its drain is connected to one end of the capacitor C, which is also connected to the input of the comparator COMP. The other end of C is grounded. The current flowing out of the drain of M7 charges and discharges the capacitor C, and finally outputs an adaptive switching frequency signal through the fourth comparator COMP.

[0036] In an optional implementation, the preheating circuit 101 has limitations on heating the lamp. For example, a lamp that has not been turned on for a long time needs to be heated when it is turned on; however, a lamp that has just been turned off (still in the working resistance state) does not need to be heated when it is turned on again. To avoid wasting the resources of the preheating circuit 101, this embodiment of the application needs to detect the lamp, and only when the preset heating requirements are detected will the lamp be heated.

[0037] In determining the heating time, this embodiment uses the current flowing through the lamp as the basis. Since the lamp's resistance changes, this embodiment employs a sampling wire connected in series with the lamp within the control circuit. It should be noted that the sampling wire differs from other wires in the adaptive control circuit; it has a certain resistance (the specific resistance value is set according to actual needs). The current flowing through the sampling wire is detected to be equal to the current flowing through the lamp. At this point, the preset heating requirement can be specifically set as a current threshold. When the current flowing through the lamp exceeds this current threshold, the lamp is heated until the current flowing through the lamp is less than or equal to the current threshold.

[0038] Furthermore, since the resistance value of the sampling wire is fixed, current detection of the sampling wire can be converted into voltage detection. That is, the aforementioned preset heating requirement can be specifically set as a voltage threshold (in this embodiment, the voltage V output by the frequency modulation circuit 102 is used). OCP As a voltage threshold, when the voltage of the sampling wire is greater than the voltage threshold, the lamp is heated until the voltage of the sampling wire is less than the voltage threshold.

[0039] When comparing the voltage of the sampling wire with a preset voltage threshold, the preheating circuit 101 in this embodiment employs a comparison module, which receives the voltage threshold V. OCP The voltage of the sampling wire is compared with the voltage. When the comparison module determines that the monitored voltage is greater than the voltage threshold range, the preheating circuit heats the lamp.

[0040] In an optional implementation, this embodiment of the application heats the lamp by using a high-frequency switching method on the switching circuit. Specifically, the preheating circuit 101 includes a trigger module and an oscillation module. The adaptive switching frequency is generated by the oscillation module and controlled by the trigger module. When the trigger module receives an enable signal, it outputs the adaptive switching frequency to the switching circuit 200. That is, in this embodiment, the switching circuit 200 controls the lamp in two ways: the first way is to control the lamp based on the initial switching frequency, and the second way is to control it based on the adaptive switching frequency. In a specific scenario, when turning on from the initial resistance, the lamp is controlled based on the adaptive switching frequency until the initial resistance of the lamp rises to the working resistance, and then the lamp is controlled based on the initial switching frequency. Specifically, the switching circuit 200 includes a pulse width modulation module, which receives the initial switching frequency and the adaptive switching frequency and outputs a pulse voltage signal. The pulse voltage signal is generated by adjusting the duty cycle based on the initial switching frequency or the adaptive switching frequency.

[0041] In an alternative implementation, such as Figure 4As shown, the preheating circuit 101 includes an oscillator (OSC), a comparator (COMP), and an RS flip-flop. The clock signal of the adaptive switching frequency output by the OSC (oscillator) is connected to the R terminal of the RS flip-flop. The COMP (comparator) compares the voltage (IR) of the sampling wire with the overcurrent protection voltage threshold (V). OCP The output of the COMP is connected to the S terminal of the RS flip-flop, and the output of the RS flip-flop then leads to the control gate. The high or low level of the COMP output controls whether the clock signal of the adaptive switching frequency generated by the OSC (oscillator) is output to the gate. Specifically, as shown... Figure 5 As shown, when IR is greater than V OCP When COMP outputs a low level, the RS flip-flop outputs a clock signal of the adaptive switching frequency generated by the OSC (oscillator) to the control gate.

[0042] In an optional implementation, the control circuit in this application embodiment can be configured according to... Figure 6 The circuit is connected to the lamp as shown. The switching circuit 200 includes a PWM (Pulse Width Modulation) module, a filter capacitor, a switching MOSFET, and a sampling wire. After the target input voltage Vin is connected to the circuit, one end of the filter capacitor is connected first, and the other end of the filter capacitor is grounded. The filtered voltage is output to the drain of the switching MOSFET. The source of the switching MOSFET is connected to one end of the sampling wire, and the other end of the sampling wire is connected to one end of the load (lamp), and the other end of the load is grounded. The output of the normal flicker frequency module (corresponding to the initial switching frequency) is connected to the PWM, and the adaptive OCP generation circuit (frequency modulation circuit 102) outputs V... OCP One end of the comparator in the PWM and preheating circuit 101 (other modules of the preheating circuit 101 are not shown) is connected to the PWM, and the output of the comparator is connected to the PWM, which is based on the normal flicker frequency and V. OCP Adjust the duty cycle and output the Gate signal to the gate of the switching MOSFET. The other input of the comparator is connected to the CS node between the sampling wire and the source of the switching MOSFET. During operation, the "normal flicker frequency" dominates under normal conditions, and the PWM generates the Gate signal based on this to control the switching MOSFET and regulate the power supply to the load. During preheating or overcurrent, the voltage of the sampling wire at the CS terminal is detected. If an overcurrent occurs, the PWM output is adjusted to protect the circuit. Through the coordinated operation of various modules, the power supply control and protection of the load (light bulb) are achieved.

[0043] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0044] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. All should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. An adaptive control circuit for a lamp, characterized in that, The resistance of the lamp changes with temperature, and the adaptive control circuit includes a control circuit and a switching circuit; the control circuit is connected to the switching circuit. The control circuit is used to output different adaptive switching frequencies; wherein, the adaptive switching frequency is used to heat the initial resistance of the lamp to the working resistance. The switching circuit is used to control the working state of the lamp.

2. The adaptive control circuit according to claim 1, characterized in that, The control circuit includes: a preheating circuit and a frequency modulation circuit; The frequency modulation circuit is used to output an adaptive switching frequency corresponding to the target input voltage of the switching circuit; The preheating circuit is used to heat the initial resistance of the lamp to the operating resistance when the voltage is not within the target voltage range.

3. The adaptive control circuit according to claim 2, characterized in that, The frequency modulation circuit includes a first conversion unit, a second conversion unit, and a third conversion unit; The first conversion unit is used to receive the target input voltage of the switching circuit and output a controlled conversion current; The second conversion unit is used to receive the controlled conversion current and output the target voltage threshold. The third conversion unit is used to output an adaptive switching frequency corresponding to the target voltage threshold.

4. The adaptive control circuit according to claim 1, characterized in that, The control circuit is used to increase the initial switching frequency of the switching circuit to an adaptive switching frequency. The switching circuit is used to control the lamp to heat its initial resistance to its operating resistance at the adaptive switching frequency.

5. The adaptive control circuit according to claim 1, characterized in that, The adaptive switching frequency includes a first switching frequency and a second switching frequency; the first switching frequency is different from the second switching frequency. The control circuit is used to receive the first input voltage of the switching circuit and output the first switching frequency. The control circuit is used to receive the second input voltage of the switching circuit and output the second switching frequency; the first input voltage is different from the second input voltage.

6. The adaptive control circuit according to claim 3, characterized in that, The first conversion unit includes a first comparator, a first MOSFET, a second MOSFET, a fourth MOSFET, an eighth MOSFET, and a first resistor; The second conversion unit includes: a second comparator, a third MOSFET, a fifth MOSFET, a sixth MOSFET, and a second resistor; The third conversion unit includes a third comparator, a third resistor, a seventh MOS transistor, a ninth MOS transistor, a tenth MOS transistor, a capacitor, and a fourth comparator.

7. The adaptive control circuit according to claim 2, characterized in that, The switching circuit is connected to the lamp via a sampling wire containing a preset resistance value; the monitoring voltage is the voltage of the sampling wire. The preheating circuit is used to detect the voltage of the sampling wire.

8. The adaptive control circuit according to claim 2, characterized in that, The preheating circuit includes: a comparison module, a trigger module, and an oscillation module; The comparison module is used to compare the monitored voltage with the voltage threshold corresponding to the target voltage range and output an enable signal; The trigger module is used to receive the enable signal and the adaptive switching frequency, and output the adaptive switching frequency when the enable signal is enabled. The oscillation module is used to output the adaptive switching frequency.

9. The adaptive control circuit according to claim 2, characterized in that, The switching circuit includes a switching MOSFET; The preheating circuit is used to control the switching of the MOSFET to heat the initial resistance of the lamp.

10. A control chip, characterized in that, Includes an adaptive control circuit as described in any one of claims 1 to 9, for controlling a lamp.

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