Headlamp height adjusting command voltage generating circuit
By setting up a buck circuit in the headlight height adjustment command voltage generation circuit, the problem of the transistor switching speed affected by temperature is solved, the stability and consistency of the command voltage output is improved, and the accuracy and safety of headlight height adjustment are ensured.
Patent Information
- Application Number
- CN202420885077.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-25
- Publication Date
- 2025-03-14
- Estimated Expiration
- 2034-04-25
AI Technical Summary
In the existing headlight height adjustment command voltage generation circuit, the switching speed of the transistor is greatly affected by the ambient temperature, resulting in a large deviation between the command voltage output at high and low temperatures and the normal temperature, affecting driving safety.
A buck circuit is provided between the base and collector of the second transistor, so that when the second transistor is turned on, its base voltage is not 0, reducing the pressure difference between the base and emitter, reducing the base current, thereby improving the shutdown response speed and the stability of the command voltage output.
By reducing the base current and voltage difference of the second transistor, the shutdown response speed is improved, the impact of temperature on transistor performance is reduced, the stability and consistency of command voltage output at high and low temperatures is improved, and the accuracy and safety of headlight height adjustment is ensured.
Smart Images
Figure CN222621239U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of automotive electronics, and in particular to a headlight height adjustment instruction voltage generating circuit. Background Art
[0002] In the field of automotive electronics, for safety reasons, car headlights are often equipped with a headlight height adjustment function. This function can manually or automatically drive the headlight height adjustment motor to adjust the headlight's irradiation height according to the vehicle's load, road conditions and other information, so as to obtain the best irradiation distance and avoid danger. The principle of headlight height adjustment is: by giving the headlight height adjustment motor a command voltage, the headlight height adjustment motor adjusts the headlight height according to the given command voltage value, and different command voltage values correspond to different heights.
[0003] In the currently commonly used command voltage generating circuit, an NPN transistor and a PNP transistor are usually used to realize level conversion. A PWM signal voltage is input to the input end of the NPN transistor, and different DC command voltages are output by adjusting the PWM duty cycle, thereby realizing continuous multi-level adjustment of the command voltage.
[0004] However, this solution has a disadvantage. The switching speed of the transistor is greatly affected by the ambient temperature. When performing high-frequency PWM switching, the deviation of the switching speed will lead to the deviation of the switching time, which will indirectly affect the output of the duty cycle, resulting in a large deviation between the command voltage output at high and low temperatures and that at normal temperature, ultimately causing the headlights to be adjusted to an unexpected height, affecting driving safety and possibly even damaging the adjustment motor. Utility Model Content
[0005] In order to solve the above problems, the present application provides a headlight height adjustment instruction voltage generating circuit.
[0006] The headlight height adjustment command voltage generating circuit provided in the embodiment of the present application includes a high-frequency voltage input terminal, a command voltage output terminal, a first triode, a second triode and a step-down circuit, wherein:
[0007] The positive electrode of the high-frequency voltage input terminal is connected to the base of the first transistor, and the negative electrode is grounded;
[0008] The first transistor is an NPN transistor, the emitter of the first transistor is grounded, and the collector is connected to the base of the second transistor through a voltage-dividing resistor;
[0009] The second transistor is a PNP transistor, the emitter of the second transistor is connected to the positive electrode of the command voltage output terminal, and the collector is grounded;
[0010] The negative electrode of the command voltage output terminal is grounded;
[0011] The step-down circuit is connected between the base and collector of the second transistor, and is used to ensure that the base voltage of the second transistor is not 0 when the second transistor is turned on, thereby reducing the voltage difference between the base and the emitter and reducing the base current of the second transistor.
[0012] In some embodiments, the step-down circuit includes at least one diode and a resistor connected in series, the anode of the diode is connected to the collector of the second transistor, and the cathode of the diode is connected to the base of the second transistor.
[0013] In some embodiments, the step-down circuit includes at least two resistors connected between the base and the collector of the second transistor.
[0014] In some embodiments, the step-down circuit includes a Zener diode and a resistor, the negative electrode of the Zener diode is connected to the base of the second transistor, and the positive electrode is grounded, one end of the resistor is connected to the collector of the second transistor, and the other end is connected between the negative electrode of the Zener diode and the base of the second transistor.
[0015] In some embodiments, a first resistor is connected between the base of the first transistor and the positive electrode of the high-frequency voltage input terminal, and a second resistor is connected between the base of the second transistor and the voltage-dividing resistor.
[0016] In some embodiments, a first bias resistor is connected between the base and the emitter of the first transistor, and a second bias resistor is connected between the base and the emitter of the second transistor.
[0017] In some embodiments, the collector of the second transistor is connected to a current limiting resistor, and the other end of the current limiting resistor is grounded.
[0018] In some embodiments, one end of the current-limiting resistor away from the second transistor is connected to a voltage-stabilizing resistor and a voltage-stabilizing capacitor in parallel, and the other ends of the voltage-stabilizing resistor and the voltage-stabilizing capacitor are grounded respectively.
[0019] The technical solution of this application has at least the following advantages:
[0020] 1. By setting a step-down circuit between the base and collector of the second triode, the collector output of the second triode is led back to the base, so that when the second triode is turned on, its base voltage is not 0, but is maintained at a level slightly lower than the emitter voltage of the second triode, thereby ensuring that the second triode is normally turned on, and reducing the voltage difference between the base and emitter of the second triode, and reducing the base current of the second triode. Under the action of the step-down circuit, the second triode will no longer be in the deep saturation region when it is turned on, thereby improving the shutdown response speed, reducing the influence of temperature on the performance of the second triode, and improving the stability and consistency of the output of the command voltage output terminal under high and low temperatures. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0022] Figure 1 is a schematic diagram of a headlight height adjustment command voltage generating circuit provided by an exemplary embodiment of the present application;
[0023] Figure 2 is a schematic diagram of a step-down circuit in a headlight height adjustment command voltage generating circuit provided by an exemplary embodiment of the present application;
[0024] Figure 3 is a schematic diagram of another step-down circuit in a headlight height adjustment command voltage generating circuit provided by an exemplary embodiment of the present application;
[0025] Figure 4 It is a schematic diagram of another step-down circuit in a headlight height adjustment command voltage generating circuit provided by an exemplary embodiment of the present application. DETAILED DESCRIPTION
[0026] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0027] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0028] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0029] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.
[0030] The present application provides a headlight height adjustment instruction voltage generation circuit, referring to Figure 1 , the circuit includes a high-frequency voltage input terminal V1, a command voltage output terminal V2, a first transistor Q1, a second transistor Q2 and a step-down circuit. Among them, the positive electrode of the high-frequency voltage input terminal V1 is connected to the base of the first transistor Q1, and the negative electrode is grounded. The high-frequency voltage input terminal V1 is used to output a high-frequency PWM voltage. Generally speaking, a high-frequency PWM voltage refers to a PWM voltage with a frequency greater than 1KHz. For example, it can be a PWM voltage with a frequency of 20KHz. In an actual vehicle system, the high-frequency voltage input terminal V1 can be connected to the Port port in the vehicle-mounted microprocessor.
[0031] The first transistor Q1 is an NPN transistor, whose emitter is grounded, and whose collector is connected to the base of the second transistor Q2 through a voltage-dividing resistor R7. The second transistor Q2 is a PNP transistor, whose emitter is connected to the positive electrode of the command voltage output terminal V2, whose collector is grounded, and whose negative electrode is grounded. The first transistor Q1 and the second transistor Q2 form a level conversion structure, which is used to convert the voltage input from the high-frequency voltage input terminal V1 into the required command voltage, and provide it to the command voltage output terminal V2.
[0032] The step-down circuit is connected between the base and the collector of the second triode Q2, and is used to make the base voltage of the second triode Q2 not 0 when it is turned on, but to maintain a level slightly lower than the emitter voltage of the second triode Q2, so as to ensure that the second triode Q2 is normally turned on, and reduce the voltage difference between the base and the emitter of the second triode Q2, and reduce the base current of the second triode Q2. Under the action of the step-down circuit, the second triode Q2 will no longer be in the deep saturation region when it is turned on, thereby improving the turn-off response speed, reducing the influence of temperature on the performance of the second triode Q2, and improving the stability and consistency of the output of the command voltage output terminal under high and low temperatures.
[0033] In one embodiment, the voltage-reducing circuit may include at least one diode and a resistor connected in series. Figure 2 As shown. Figure 2 In the circuit shown, the step-down circuit includes a resistor R8 and two diodes D1 and D2 connected in series, wherein the anode of the diode D1 is connected to the collector of the second transistor Q2, the cathode is connected to the anode of the diode D2, the cathode of the diode D2 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the base of the second transistor Q2.
[0034] In another embodiment, the voltage-reducing circuit may include at least two resistors connected in series. Figure 3 As shown. Figure 3 In the circuit shown, the step-down circuit includes two resistors R9 and R 10 , wherein the other end of the resistor R9 is connected to the collector of the second transistor Q2, and the resistor R 10 The other end is connected to the base of the second transistor Q2.
[0035] In another embodiment, the voltage-reducing circuit may include a voltage-stabilizing tube and a resistor. For example, Figure 4 As shown. Figure 4 In the circuit shown, the step-down circuit includes a voltage regulator tube D3 and a resistor R 11 , the cathode of the voltage regulator tube D3 is connected to the base of the second transistor Q2, the anode is grounded, and the resistor R 11 One end of is connected to the collector of the second triode Q2, and the other end is connected between the cathode of the voltage regulator tube D3 and the base of the second triode Q2.
[0036] Further, in order to improve the stability of the base voltage of the first transistor Q1 and the second transistor Q2, refer to Figure 1A first resistor R1 is connected between the base of the first transistor Q1 and the positive electrode of the high-frequency voltage input terminal V1, and a second resistor R2 is connected between the base of the second transistor Q2 and the voltage-dividing resistor R7. One end of the step-down circuit connected to the base of the second transistor Q2 is connected between the voltage-dividing resistor R7 and the second resistor R2.
[0037] Furthermore, a first bias resistor R3 is connected between the base and the emitter of the first transistor Q1 , and a second bias resistor R4 is connected between the base and the emitter of the second transistor Q2 .
[0038] Further, see Figure 1 The collector of the second transistor Q2 is connected to a current limiting resistor R5, and the other end of the current limiting resistor R5 is grounded. In order to further improve the stability of the output voltage, one end of the current limiting resistor R5 away from the second transistor Q2 is connected to a parallel voltage stabilizing resistor R6 and a voltage stabilizing capacitor C1, and the other ends of the voltage stabilizing resistor R6 and the voltage stabilizing capacitor C1 are grounded respectively.
[0039] The embodiment of the present application provides a headlight height adjustment command voltage generating circuit, which provides a step-down circuit between the base and collector of the second transistor Q2, and leads the collector output of the second transistor Q2 back to the base, so that when the second transistor Q2 is turned on, its base voltage is not 0, but is maintained at a level slightly lower than the emitter voltage of the second transistor Q2, thereby ensuring that the second transistor Q2 is turned on normally, and reducing the voltage difference between the base and emitter of the second transistor Q2, and reducing the base current of the second transistor Q2. Under the action of the step-down circuit, the second transistor Q2 will no longer be in the deep saturation region when it is turned on, thereby improving the shutdown response speed, reducing the influence of temperature on the performance of the second transistor Q2, and improving the stability and consistency of the output of the command voltage output terminal under high and low temperatures. At the same time, good high and low temperature characteristics can also allow higher headlight height adjustment accuracy.
[0040] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.
Claims
1. A headlight height adjustment command voltage generating circuit, characterized in that: It includes a high-frequency voltage input terminal, a command voltage output terminal, a first triode, a second triode and a step-down circuit, wherein: The positive electrode of the high-frequency voltage input terminal is connected to the base of the first transistor, and the negative electrode is grounded; The first transistor is an NPN transistor, the emitter of the first transistor is grounded, and the collector is connected to the base of the second transistor through a voltage-dividing resistor; The second transistor is a PNP transistor, the emitter of the second transistor is connected to the positive electrode of the command voltage output terminal, and the collector is grounded; The negative electrode of the command voltage output terminal is grounded; The step-down circuit is connected between the base and collector of the second transistor, and is used to ensure that the base voltage of the second transistor is not 0 when the second transistor is turned on, thereby reducing the voltage difference between the base and the emitter and reducing the base current of the second transistor.
2. The headlight height adjustment command voltage generating circuit according to claim 1, characterized in that: The step-down circuit includes at least one diode and a resistor connected in series, wherein the anode of the diode is connected to the collector of the second transistor, and the cathode of the diode is connected to the base of the second transistor.
3. The headlight height adjustment command voltage generating circuit according to claim 1, characterized in that: The step-down circuit includes at least two resistors connected between the base and the collector of the second transistor.
4. The headlight height adjustment command voltage generating circuit according to claim 1, characterized in that: The step-down circuit includes a voltage regulator and a resistor, wherein the cathode of the voltage regulator is connected to the base of the second transistor and the anode is grounded, one end of the resistor is connected to the collector of the second transistor and the other end is connected between the cathode of the voltage regulator and the base of the second transistor.
5. The headlight height adjustment command voltage generating circuit according to claim 1, characterized in that: A first resistor is connected between the base of the first transistor and the positive electrode of the high-frequency voltage input terminal, and a second resistor is connected between the base of the second transistor and the voltage-dividing resistor.
6. The headlight height adjustment command voltage generating circuit according to claim 1, characterized in that: A first bias resistor is connected between the base and emitter of the first transistor, and a second bias resistor is connected between the base and emitter of the second transistor.
7. The headlight height adjustment command voltage generating circuit according to claim 1, characterized in that: The collector of the second transistor is connected to a current limiting resistor, and the other end of the current limiting resistor is grounded.
8. The headlight height adjustment command voltage generating circuit according to claim 7, characterized in that: One end of the current-limiting resistor away from the second triode is connected to a voltage-stabilizing resistor and a voltage-stabilizing capacitor in parallel, and the other ends of the voltage-stabilizing resistor and the voltage-stabilizing capacitor are grounded respectively.