Control system for automobile interior lamp

Abstract

The utility model discloses a control system for an automobile interior lamp, which relates to the field of automobile interior lamp control and comprises a constant voltage circuit, a first voltage stabilizing circuit, a second voltage stabilizing circuit and a control circuit, and is characterized in that the constant voltage circuit comprises a first transistor DT1 and a first triode Q1; the base electrode of the first transistor DT1 is connected with the MCU controller, the emitter electrode is grounded, and the collector electrode is connected with the base electrode of the first triode Q1; the emitter of the first triode Q1 is connected to a power supply, and the collector is connected to the anode of an automobile interior lamp; the constant voltage circuit is used for accessing a PWM (Pulse Width Modulation) signal output by the MCU controller and controlling the on-off state of the first triode Q1 through the PWM signal; according to the utility model, the on-off state of the first transistor DT1 and the first triode Q1 is controlled through the PWM signal, and the voltage flowing through the interior lamp of the automobile is adjusted.

Description

TECHNICAL FIELD

[0001] The utility model relates to the control field of car interior light, especially a control system for car interior light. BACKGROUND

[0002] Under the background of the vigorous development of the automotive electronics industry, the brightness requirement, control requirement and diagnosis requirement of the reading light and the ceiling light in the car are higher and higher. Although there are special LED driving chips on the market at present, the chips integrate multiple functions such as PWM control, constant current output, diagnosis and short circuit protection, but the cost of these chips is high. The purpose of the utility model is to design a circuit without reducing the functional requirements, which can meet the above functional requirements and significantly reduce the circuit cost. The PWM control, constant current output, diagnosis and short circuit protection functions are realized by using basic discrete components (such as transistors, diodes and resistors). CONTENT OF THE UTILITY MODEL

[0003] In order to realize the PWM control, constant current output, short circuit protection and other functions at low cost, the utility model provides a control system for car interior light, which comprises:

[0004] The constant voltage circuit comprises a first transistor DT1 and a first triode Q1. The base of the first transistor DT1 is connected with the MCU controller, the emitter is grounded, and the collector is connected with the base of the first triode Q1. The emitter of the first triode Q1 is connected with the power supply, and the collector is connected with the positive electrode of the car interior light. The constant voltage circuit is used for connecting the PWM signal output by the MCU controller, and controlling the on-off state of the first triode Q1 through the PWM signal, so that the working voltage of the car interior light is kept stable.

[0005] Further, the MCU controller is used for generating and outputting the PWM signal, and adjusting the duty cycle of the PWM signal according to the detected power supply voltage.

[0006] Further, the control system further comprises:

[0007] The feedback circuit electrically connected with the positive electrode of the car interior light is used for monitoring the input voltage of the car interior light and feeding back to the MCU controller.

[0008] The short circuit protection circuit is used for monitoring the grounding state of the power supply input pin of the car interior light, and controlling the first triode Q1 to be cut off when the power supply input pin is short-circuited to the ground.

[0009] Further, the constant voltage circuit further comprises:

[0010] The sixth resistor R6 is connected with the third resistor R3; one end of the sixth resistor R6 is connected with the collector of the first transistor DT1; the base of the first transistor Q1 is connected with the collector of the second transistor Q2 in the short circuit protection circuit; the other end of the sixth resistor R6 is connected with one end of the third resistor R3 and then connected to the connecting line where the base of the first transistor Q1 and the collector of the second transistor Q2 are connected; the other end of the third resistor R3 is connected with the emitter of the first transistor Q1 and then connected to the power supply; the collector of the first transistor Q1 is connected with one end of the fourth resistor R4 and then connected to one end of the first resistor R1; the other end of the fourth resistor R4 is connected with the second pin of the double diode D1; the other end of the first resistor R1 is connected with the first pin of the double diode D1, the short circuit protection circuit and the feedback circuit in sequence and then connected to the internal lamp of the automobile.

[0011] Further, when the PWM signal is high, the base of the first transistor DT1 is in a high potential state, the emitter is in a low potential state, and the first transistor DT1 is turned on. At this time, the base of the first transistor Q1 is pulled to the ground potential, the emitter of the first transistor Q1 is in a high potential state, and the first transistor Q1 is turned on.

[0012] When the PWM signal is low, the base of the first transistor DT1 is in a low potential state, and the emitter is also in a low potential state. The first transistor DT1 is turned off. At this time, the base of the first transistor Q1 is pulled to a high potential state, the emitter of the first transistor Q1 is in a high potential state, and the first transistor Q1 is turned off.

[0013] Further, the feedback circuit specifically includes:

[0014] The fifth resistor R5 is connected with the seventh resistor R7; one end of the fifth resistor R5 is connected with one end of the seventh resistor R7, and the connecting end of the fifth resistor R5 and the seventh resistor R7 is connected to the MCU controller; the other end of the seventh resistor R7 is grounded, and the other end of the fifth resistor R5 is connected with one end of the first resistor R1.

[0015] Further, the short circuit protection circuit includes:

[0016] Eleventh resistance R11 and tenth resistance R10, one end of the eleventh resistance R11 is connected with one end of the first resistance R1, that is, the power input pin, the other end is connected with the emitter of the second transistor DT2, the collector of the second transistor DT2 is connected with one end of the eighth resistance R8, the other end of the eighth resistance R8 is sequentially connected with one end of the first capacitor C1 and one end of the ninth resistance R9, and then is connected to the base of the second triode Q2, the other end of the first capacitor C1 is connected with the other end of the ninth resistance R9, and then is connected to the emitter of the second triode Q2, the emitter of the second triode Q2 is also connected with the power supply, one end of the tenth resistance R10 is connected with the base of the second transistor DT2, and the other end of the tenth resistance R10 is grounded.

[0017] Further, in the short circuit protection circuit, when the power input pin is short-circuited to the ground, the voltage of the eleventh resistance R11 is pulled to the ground potential, and the emitter of the second transistor DT2 is also pulled to the ground potential, so that the second transistor DT2 is turned on; with the turn-on of the second transistor DT2, the eighth resistance R8 is pulled to the ground potential, and the base of the second triode Q2 is also pulled to the ground potential, so that the second triode Q2 is turned on; after the second triode Q2 is turned on, the base of the first triode Q1 is pulled to the voltage value of the power supply, so that the first triode Q1 is cut off, thereby cutting off the voltage flowing to the automobile interior lamp.

[0018] Further, one end of the automobile interior lamp DL1 is connected with the power input pin, and the other end is connected with one end of the second resistance R2; the other end of the second resistance R2 is grounded.

[0019] Further, the automobile interior lamp DL1 is a reading lamp or a ceiling lamp.

[0020] Compared with the prior art, the utility model at least has the following beneficial effects:

[0021] (1) in the utility model, the constant voltage circuit, it includes: first transistor DT1 and first triode Q1;The base of the first transistor DT1 is connected with the MCU controller, the emitter is grounded, and the collector is connected with the base of the first triode Q1;The emitter of the first triode Q1 is connected with the power supply, and the collector is connected with the positive electrode of the automobile interior lamp;The constant voltage circuit is used to connect the PWM signal output by the MCU controller, and the on-off state of the first triode Q1 is controlled through the PWM signal;That is, the utility model controls the on-off state (turning on or cutting off) of the first transistor DT1 and the first triode Q1 through the PWM signal, and realizes the adjustment of the voltage flowing through the automobile interior lamp;

[0022] (2) The utility model discloses, MCU controller, for generating PWM signal and output, and according to the detected power voltage adjustment PWM signal's duty cycle, through this PWM signal has ensured that the automobile interior light brightness is stable and adjustable;

[0023] (3) The utility model discloses through using basic discrete component (such as transistor, diode and resistance) replaces expensive special LED drive chip, has reduced the circuit cost significantly while realizing PWM control, constant current output and short circuit protection and multiple functions such as;

[0024] (4) The utility model discloses through short circuit protection circuit, when power input pin is short-circuited to ground, the circuit can respond quickly, cut off the voltage of automobile interior light, prevents circuit damage. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a kind of circuit structure diagram for the control system of automobile interior light. DETAILED DESCRIPTION

[0026] The following is the specific embodiment of the present application and further describes the technical scheme of the present application in conjunction with the drawings, but the present application is not limited to these embodiments.

[0027] In order to realize PWM control, constant current output, short circuit protection and multiple functions such as low cost, as shown in the utility model discloses a kind of control system for automobile interior light, comprising: Figure 1

[0028] Constant voltage circuit, it includes: first transistor DT1 and first triode Q1;The base of the first transistor DT1 is connected with MCU controller, the emitter is grounded, and the collector is connected with the base of the first triode Q1;The emitter of the first triode Q1 is connected with 12V-SYS power supply (i.e. automobile power supply), and the collector is connected with the positive electrode of automobile interior light;The constant voltage circuit is used to input the PWM signal output by MCU controller, and the on-off state of the first triode Q1 is controlled by PWM signal, so that the working voltage of automobile interior light is kept stable.

[0029] The MCU controller is used to generate and output PWM signal, and adjust the duty cycle of PWM signal according to the detected power voltage (i.e. the voltage of 12V-SYS power supply).

[0030] The constant voltage circuit further comprises:

[0031] ​The sixth resistor R6 is connected with the third resistor R3; one end of the sixth resistor R6 is connected with the collector of the first transistor DT1; the base of the first transistor Q1 is connected with the collector of the second transistor Q2 in the short circuit protection circuit; the other end of the sixth resistor R6 is connected with one end of the third resistor R3 and then connected to the connecting line where the base of the first transistor Q1 and the collector of the second transistor Q2 are connected; the other end of the third resistor R3 is connected with the emitter of the first transistor Q1 and then connected to the 12V-SYS power supply; the collector of the first transistor Q1 is connected with one end of the fourth resistor R4 and then connected to one end of the first resistor R1; the other end of the fourth resistor R4 is connected with the second pin of the double diode D1; the other end of the first resistor R1 is connected with the first pin of the double diode D1, the short circuit protection circuit and the feedback circuit in turn and then connected to the automobile interior lamp.

[0032] When the PWM signal is high, the base of the first transistor DT1 is in a high potential state, the emitter is in a low potential state, and the first transistor DT1 is turned on. At this time, the base of the first transistor Q1 is pulled to the ground potential, the emitter of the first transistor Q1 is in a high potential state, and the first transistor Q1 is turned on.

[0033] When the PWM signal is low, the base of the first transistor DT1 is in a low potential state, and the emitter is also in a low potential state. The first transistor DT1 is turned off. At this time, the base of the first transistor Q1 is pulled to a high potential state, the emitter of the first transistor Q1 is in a high potential state, and the first transistor Q1 is turned off.

[0034] Specifically, the states (on or off) of the transistors DT1 and Q1 are controlled by the PWM signal, and then the current flowing through the automobile interior lamp is adjusted. When the duty ratio (i.e. the ratio of the high level duration to the period) of the PWM signal increases, the transistor is turned on for a longer time, and more current can pass through the automobile interior lamp, and vice versa. In this way, even if the power supply voltage fluctuates, the average voltage (V_Average) across the automobile interior lamp can be maintained at 10.5V by adjusting the duty ratio of the PWM signal, so that the brightness of the automobile interior lamp remains consistent and no visible brightness change occurs. The MCU controller continuously monitors the power supply voltage. If the power supply voltage rises, the MCU will reduce the duty ratio of the PWM signal and reduce the time ratio of the high level to reduce the current; if the power supply voltage decreases, the MCU will increase the duty ratio of the PWM signal and increase the time ratio of the high level to increase the current. In this way, the brightness of the automobile interior lamp can remain stable regardless of the changes in the power supply voltage.

[0035] The utility model discloses a constant voltage circuit, it includes: first transistor DT1 and first triode Q1, the base of first transistor DT1 is connected with MCU controller, the emitter ground, the collector is connected with the base of first triode Q1, the emitter of first triode Q1 is connected power supply, and the collector is connected with the positive pole of car interior light, the constant voltage circuit is used for connecting the PWM signal of MCU controller output, and the on-off state of first triode Q1 is controlled through PWM signal, namely, the utility model discloses through the on-off state (conducting or cut-off) of PWM signal control first transistor DT1 and first triode Q1, has realized the adjustment to the voltage size of car interior light.

[0036] The control system further comprises:

[0037] The feedback circuit electrically connected with the positive pole of the car interior light is used for monitoring the input voltage of the car interior light and feeding back to the MCU controller.

[0038] The feedback circuit specifically comprises:

[0039] The fifth resistor R5 and the seventh resistor R7, one end of the fifth resistor R5 is connected with one end of the seventh resistor R7, and the connecting end of the fifth resistor R5 and the seventh resistor R7 is connected with the MCU controller, the other end of the seventh resistor R7 is grounded, and the other end of the fifth resistor R5 is connected with one end of the first resistor R1.

[0040] In the embodiment, a voltage dividing network is formed by the fifth resistor R5 and the seventh resistor R7, and the input voltage of the car interior light is divided by a certain proportion and then fed back to an input pin (IN_MCU_ReadingLamp_DIAG) of the MCU controller. Figure 1 The MCU controller can realize real-time understanding of the actual working state of the car interior light by monitoring the feedback voltage, including but not limited to whether the voltage is normal, whether there is abnormal heating and the like, so as to realize fault diagnosis.

[0041] The short-circuit protection circuit is used for monitoring the grounding state of the power input pin of the car interior light, and the first triode Q1 is controlled to be cut off when the power input pin is short-circuited to the ground.

[0042] The short-circuit protection circuit comprises:

[0043] Eleventh resistor R11 and tenth resistor R10; one end of the eleventh resistor R11 is connected with one end of the first resistor R1, i.e. the power input pin, and the other end is connected with the emitter of the second transistor DT2; the collector of the second transistor DT2 is connected with one end of the eighth resistor R8; the other end of the eighth resistor R8 is connected with one end of the first capacitor C1 and one end of the ninth resistor R9 in turn, and then connected with the base of the second transistor Q2; the other end of the first capacitor C1 and the other end of the ninth resistor R9 are connected, and then connected with the emitter of the second transistor Q2; the emitter of the second transistor Q2 is also connected with the 12V-SYS power supply; the base of the second transistor DT2 is connected with one end of the tenth resistor R10, and then connected with the third pin of the double diode D1; the other end of the tenth resistor R10 is grounded.

[0044] In the short circuit protection circuit: when the power input pin is short-circuited to the ground, the voltage of the eleventh resistor R11 is pulled to the ground potential, and at the same time the emitter of the second transistor DT2 is also pulled to the ground potential, causing the second transistor DT2 to turn on; with the turn-on of the second transistor DT2, the eighth resistor R8 is pulled to the ground potential, and at the same time the base of the second transistor Q2 is also pulled to the ground potential, causing the second transistor Q2 to turn on; after the second transistor Q2 turns on, the base of the first transistor Q1 is pulled to the voltage value of the 12V-SYS power supply, causing the first transistor Q1 to be cut off, thereby cutting off the voltage flowing to the car interior lamp.

[0045] Specifically:

[0046] 1. The power input pin is short-circuited to the ground:

[0047] When the power input pin is short-circuited to the ground, one end of the eleventh resistor R11 is pulled to the ground potential, and the other end is also pulled to the ground potential.

[0048] 2. The second transistor DT2 turns on:

[0049] The voltage of the eleventh resistor R11 is pulled to the ground potential, and at the same time the emitter of the second transistor DT2 is also pulled to the ground potential. Since the emitter of DT2 is pulled to the ground potential, and its base (connected to the 12V-SYS power supply through other circuits) still maintains a high potential, the voltage difference between the base and the emitter of DT2 is sufficient to make it turn on.

[0050] 3. The eighth resistor R8 is pulled to the ground potential:

[0051] With the turn-on of DT2, its collector is pulled to the ground potential. One end of the eighth resistor R8 is connected to the collector of DT2, so one end of R8 is also pulled to the ground potential.

[0052] 4. The second transistor Q2 turns on:

[0053] The eighth resistor R8 is pulled to ground potential, and the base of the second transistor Q2 is also pulled to ground potential. Since the base of Q2 is pulled to ground potential and its emitter is connected to the 12V-SYS power supply, the voltage difference between the base and the emitter is sufficient to turn on Q2.

[0054] 5. The first transistor Q1 is turned off:

[0055] After the second transistor Q2 is turned on, its collector is pulled to the voltage value of the 12V-SYS power supply. The base of the first transistor Q1 is pulled to the voltage value of the 12V-SYS power supply through the collector of Q2. Since the base of Q1 is pulled to the voltage value of the 12V-SYS power supply and its emitter is also connected to the 12V-SYS power supply, the voltage difference between the base and the emitter is 0V, and Q1 is turned off.

[0056] 6. The voltage flowing to the LED is cut off:

[0057] After the first transistor Q1 is turned off, no current passes between its collector and emitter, thereby cutting off the voltage flowing to the LED and achieving short circuit protection.

[0058] Through the series of actions, the short circuit protection circuit can quickly respond and cut off the voltage of the automobile interior lamp when the power input pin is shorted to ground, thereby preventing damage to the circuit.

[0059] One end of the automobile interior lamp DL1 is connected to the power input pin, and the other end is connected to one end of the second resistor R2; the other end of the second resistor R2 is grounded.

[0060] The automobile interior lamp DL1 is a reading lamp or a ceiling lamp.

[0061] The utility model discloses a basic discrete component (such as transistor, diode and resistance) is used to replace the expensive special LED drive chip, and multiple functions such as PWM control, constant current output and short circuit protection are realized while the circuit cost is reduced significantly.

[0062] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directional indications will also change accordingly.

[0063] In addition, the descriptions such as "first", "second", "one", etc. in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0064] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixing", etc. should be understood broadly, for example, "fixing" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0065] In addition, the technical solutions of various embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, when the combination of technical solutions appears contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist, nor is it within the protection scope required by the present application.

Claims

1. A control system for an automotive interior light, characterized by, The control system comprises a constant voltage circuit, which comprises a first transistor DT1 and a first triode Q1. The base of the first transistor DT1 is connected with the MCU controller, the emitter is grounded, and the collector is connected with the base of the first triode Q1; the emitter of the first triode Q1 is connected with a power supply, and the collector is connected with the positive electrode of the automobile interior lamp; the constant voltage circuit is used for connecting with the PWM signal output by the MCU controller, and the on-off state of the first triode Q1 is controlled through the PWM signal, so that the working voltage of the automobile interior lamp is kept stable.

2. The control system for the automobile interior lamp according to claim 1, wherein the MCU controller is used for generating and outputting the PWM signal, and adjusting the duty cycle of the PWM signal according to the detected power supply voltage. The control system further comprises a feedback circuit connected with the positive electrode of the automobile interior lamp, which is used for monitoring the input voltage of the automobile interior lamp and feeding back to the MCU controller; and a short-circuit protection circuit, which is used for monitoring the grounding state of the power supply input pin of the automobile interior lamp, and controlling the first triode Q1 to be cut off when the power supply input pin is short-circuited to the ground. The constant voltage circuit further comprises a sixth resistor R6 and a third resistor R3; one end of the sixth resistor R6 is connected with the collector of the first transistor DT1; the base of the first triode Q1 is connected with the collector of a second triode Q2 in the short-circuit protection circuit; the other end of the sixth resistor R6 is connected with one end of the third resistor R3, and then connected to the connection line where the base of the first triode Q1 and the collector of the second triode Q2 are connected; the other end of the third resistor R3 is connected with the emitter of the first triode Q1, and then connected with the power supply; the collector of the first triode Q1 is connected with one end of a fourth resistor R4, and then connected with one end of a first resistor R1; the other end of the fourth resistor R4 is connected with the second pin of a double diode D1; the other end of the first resistor R1 is connected with the first pin of the double diode D1, the short-circuit protection circuit, the feedback circuit in sequence, and then connected with the automobile interior lamp.

3. The control system for the automotive interior light according to claim 1, wherein 5. The control system for the automobile interior lamp according to claim 4, wherein when the PWM signal is at a high level, the base of the first transistor DT1 is at a high potential state, the emitter is at a low potential state, the first transistor DT1 is turned on, at this time, the base of the first triode Q1 is pulled to the ground potential, the emitter of the first triode Q1 is at a high potential state, and the first triode Q1 is turned on; when the PWM signal is at a low level, the base of the first transistor DT1 is at a low potential state, the emitter is also at a low potential state, the first transistor DT1 is cut off, at this time, the base of the first triode Q1 is pulled to a high potential state, the emitter of the first triode Q1 is at a high potential state, and the first triode Q1 is cut off. The feedback circuit specifically comprises a fifth resistor R5 and a seventh resistor R7; one end of the fifth resistor R5 is connected with one end of the seventh resistor R7, and the connection end where the fifth resistor R5 and the seventh resistor R7 are connected is connected with the MCU controller; the other end of the seventh resistor R7 is grounded, and the other end of the fifth resistor R5 is connected with one end of the first resistor R1. ​ 4. The control system for an automotive interior lamp according to claim 3, wherein ​ ​ ​ ​ ​ 6. The control system for an automotive interior lamp according to claim 4, wherein ​ ​ 7. The control system for an automotive interior light according to claim 6, wherein The short-circuit protection circuit comprises: The eleventh resistor R11 and the tenth resistor R10; one end of the eleventh resistor R11 is connected with one end of the first resistor R1, that is, the power input pin, and the other end is connected with the emitter of the second transistor DT2; the collector of the second transistor DT2 is connected with one end of the eighth resistor R8; the other end of the eighth resistor R8 is sequentially connected with one end of the first capacitor C1 and one end of the ninth resistor R9, and then connected with the base of the second triode Q2; the other end of the first capacitor C1 is connected with the other end of the ninth resistor R9, and then connected with the emitter of the second triode Q2; the emitter of the second triode Q2 is also connected with the power supply; the base of the second transistor DT2 is connected with one end of the tenth resistor R10, and then connected with the third pin of the double diode D1; the other end of the tenth resistor R10 is grounded.

8. The control system for the automotive interior lamp according to claim 7, wherein, In the short-circuit protection circuit: when the power input pin is short-circuited to the ground, the voltage of the eleventh resistor R11 is pulled to the ground potential, and at the same time, the emitter of the second transistor DT2 is also pulled to the ground potential, resulting in that the second transistor DT2 is turned on; with the turn-on of the second transistor DT2, the eighth resistor R8 is pulled to the ground potential, and at the same time, the base of the second triode Q2 is also pulled to the ground potential, so that the second triode Q2 is turned on; after the second triode Q2 is turned on, the base of the first triode Q1 is pulled to the voltage value of the power supply, resulting in that the first triode Q1 is cut off, so as to cut off the voltage flowing to the automotive interior lamp.

9. The control system for an automotive interior lamp according to claim 8, wherein One end of the automotive interior lamp DL1 is connected with the power input pin, and the other end is connected with one end of the second resistor R2; the other end of the second resistor R2 is grounded.

10. The control system for an automotive interior light according to any one of claims 1 to 9, characterized in that, The automotive interior lamp DL1 is a reading lamp or a ceiling lamp.

Images