Automobile indoor lamp dimming circuit based on PWM (Pulse Width Modulation)
The microcontroller outputs PWM signals with different duty cycles to control the on-off frequency of the transistor, which solves the problem of small brightness and color adjustment range of existing automobile indoor lights, realizes the adjustment of multi-range brightness and color, and improves the user experience.
Patent Information
- Application Number
- CN202422290753.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-19
- Publication Date
- 2025-08-05
- Estimated Expiration
- 2034-09-19
AI Technical Summary
The existing car interior lights and reading lights have a small brightness adjustment range, which cannot meet the needs of multiple brightnesses. The backlight can only switch a few colors, making it impossible to achieve multi-range color selection and adjustment.
The microcontroller unit is used to output PWM signals with different duty cycles, control the on-off frequency of the transistor, realize multi-range brightness adjustment of indoor lamps and reading lamps, and realize the color and brightness adjustment of the backlight LED by adjusting the duty cycle of the PWM signal.
It realizes multi-range brightness adjustment of indoor lights and reading lights, improves user comfort, and can switch multiple colors to meet the lighting needs of different environments.
Smart Images
Figure CN223194866U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of automobile interior light dimming, in particular to an automobile interior light dimming circuit based on PWM. Background Art
[0002] The statements herein merely provide background art related to the present invention and do not necessarily constitute prior art.
[0003] Car interior lights often use LED lights as the main tool for interior lighting, which can ensure that the car is well-lit at night and facilitate people's activities in the car. However, existing car interior lights are often only able to adjust the brightness in three levels, with a small range of application, and cannot independently adjust the interior light brightness in a wide range according to the needs of the people. For example, when the brightness of the interior light is too high, it can easily cause glare to people in the car; if the brightness is too low, it cannot effectively illuminate the car interior. Existing cars are also equipped with reading lights to facilitate reading. The brightness adjustment range of the reading lights is also very small and cannot effectively meet the brightness needs of people when reading. To further enhance the atmosphere in the car, a circle of backlights is often set on the outside of the interior lights and reading lights. Currently, the interior light backlights and reading light backlights can only switch between a few colors, and cannot achieve the selection and adjustment of a wide range of color types. Utility Model Content
[0004] The purpose of the utility model is to provide a PWM-based automobile interior light dimming circuit, comprising a touch control unit and an interior light adjustment unit; the touch control unit and the interior light adjustment unit are both connected to a micro control unit;
[0005] The microcontroller unit outputs PWM signals with different duty cycles to the indoor light adjustment unit; the indoor light adjustment unit includes a plurality of first transistors connected in parallel, the base of each first transistor is connected to the first constant current circuit, the emitter of each first transistor is also connected to the current limiting circuit, and the collector of the first transistor is connected to the indoor light LED array.
[0006] As a further technical solution, one end of the constant current circuit is connected to the pin of the micro control unit, and the other end is connected to the base of the transistor; the constant current circuit includes a first resistor and a second resistor connected to one end of the first resistor, a capacitor and a Zener diode, wherein the second resistor, capacitor and Zener diode are connected in parallel and the other end is grounded.
[0007] As a further technical solution, the current limiting circuit includes a third resistor and a fourth resistor connected in parallel with each other, one end of the third resistor and the fourth resistor is connected to the emitter of the transistor, and the other end is grounded.
[0008] As a further technical solution, an interior light backlight LED is also arranged around the car interior light. The PWM-based car interior light dimming circuit also includes an interior light backlight adjustment unit. The micro control unit also outputs PWM signals with different duty cycles to the interior light backlight adjustment unit.
[0009] As a further technical solution, the indoor light backlight adjustment unit includes three third transistors connected in parallel, the base of each third transistor is connected to the constant current circuit; the emitter of each third transistor is connected to the current limiting circuit, the collector of each third transistor is connected to the indoor light backlight LED array, and a fifth resistor is also connected in series between the collector of the third transistor and the indoor light backlight LED array.
[0010] As a further technical solution, the PWM-based automobile interior light dimming circuit further includes a reading light adjustment unit, and the microcontroller unit further outputs PWM signals with different duty cycles to the reading light adjustment unit.
[0011] As a further technical solution, the reading light adjustment unit is set to two, each reading light adjustment unit includes a second transistor, a constant current circuit, a current limiting circuit and a reading light LED array; wherein the constant current circuit is connected to the base of the second transistor, the current limiting circuit is connected to the emitter of the second transistor, and the reading light LED array is connected to the collector of the second transistor.
[0012] As a further technical solution, a reading light backlight LED is also arranged around the reading light. The PWM-based automobile interior light dimming circuit also includes a reading light backlight adjustment unit. The micro control unit also outputs PWM signals with different duty cycles to the reading light backlight adjustment unit.
[0013] As a further technical solution, the reading light backlight adjustment unit includes three fourth transistors connected in parallel, the base of each fourth transistor is connected to the constant current circuit; the emitter of each fourth transistor is connected to the current limiting circuit, and the collector of each fourth transistor is connected to the reading light backlight LED array.
[0014] As a further technical solution, three sixth resistors are further connected between the collector of the fourth transistor and the reading light backlight LED array, and the sixth resistors are connected in parallel.
[0015] Beneficial effects of one or more of the above technical solutions:
[0016] By outputting PWM signals with varying duty cycles from the microcontroller unit, the first transistor in the interior light control unit can be rapidly switched on and off at varying frequencies, enabling multi-range brightness adjustment of the interior light LED array to meet various brightness requirements. The microcontroller is also connected to the reading light control unit, also outputting PWM signals with varying duty cycles to adjust the reading light's brightness.
[0017] The microcontroller unit is also connected to the interior light backlight adjustment unit and the reading light backlight adjustment unit. The color and brightness of the interior light backlight LED and the reading light backlight LED can be adjusted by using the PWM signals with different duty cycles output by the microcontroller processor, thereby achieving switching between different colors and changes in different brightness, further improving the comfort of the personnel. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation on this application.
[0019] Figure 1 It is a structural diagram of the micro control unit of the present utility model.
[0020] Figure 2 This is a schematic diagram of the circuit principle of the touch unit of the present invention.
[0021] Figure 3 This is a schematic diagram of the circuit principle of the indoor light adjustment unit of the present utility model.
[0022] Figure 4 This is a schematic diagram of the circuit principle of the room reading adjustment unit of the present utility model.
[0023] Figure 5 This is a schematic diagram of the circuit principle of the indoor lamp backlight adjustment unit of the present utility model.
[0024] Figure 6 This is a schematic diagram of the circuit principle of the reading light backlight adjustment unit of the present invention. DETAILED DESCRIPTION
[0025] The following is combined with Figure 1-6 , describing the specific implementation of this embodiment.
[0026] The embodiment of the present application provides a PWM-based automobile interior light dimming circuit, referring to Figure 1 A PWM-based automobile interior light dimming circuit includes a touch control unit, an interior light adjustment unit, and a reading light adjustment unit; the touch control unit, the interior light adjustment unit, and the reading light adjustment unit are all connected to a micro control unit. Figure 1 and Figure 2The touch unit uses the SJ8005 chip and is connected to a capacitive touch film. The touch film contains six pin output connectors for outputting touch signals. Pin1 and Pin6 are grounded. Pin2 is connected to the interior light switch on one end and to the Touch1_L pin 8 on the touch unit on the other end. Pin3 is connected to the reading light switch on one end and to the Touch2_L pin 7 on the touch unit on the other end. Pin4 is connected to the interior light brightness increase button on one end and to the Touch3_L pin 6 on the touch unit on the other end. Pin5 is connected to the interior light brightness decrease button on one end and to the Touch4_L pin 5 on the touch unit on the other end.
[0027] The microcontroller uses the BAT32A237KH48FA chip, which can output PWM signals with varying duty cycles, adjusting the transistors to switch on and off at varying frequencies. PWM dimming is a technique for controlling analog circuits by adjusting pulse width. It works by adjusting the LED's brightness by controlling the on and off time within a fixed time period. A larger on-off time ratio increases the LED's brightness; a smaller on-off time ratio decreases its brightness. Within each time period, the LED flickers rapidly at a certain frequency, imperceptible to the human eye, thus achieving brightness adjustment. In simple terms, PWM dimming adjusts light brightness by varying the ratio of high-level to low-level time. Specifically, PWM dimming uses a set period (for example, 10 milliseconds) and adjusts the light's brightness by varying the ratio of high-level (light on) to low-level (light off) time within that period. For example, if the voltage is high throughout the entire cycle, the light is brightest; if the voltage is high for half of the entire cycle, the light is 50% of its brightest state; if the voltage is low throughout the entire cycle, the light is completely off.
[0028] Combine Figure 1 and Figure 2 , the Touch1_L 8 pin of the touch unit is connected to the Out1_L 39 pin of the microcontroller unit, the Touch2_L 7 pin is connected to the Out2_L 40 pin of the microcontroller unit, the Touch3_L 6 pin is connected to the Out3_L 41 pin of the microcontroller unit, and the Touch4_L 5 pin is connected to the Out4_L 42 pin of the microcontroller unit.
[0029] Combine Figure 3 Pin 32 of the microcontroller unit is connected to the interior light adjustment unit. The interior light adjustment unit includes a plurality of first transistors connected in parallel. The base of each first transistor is connected to a constant current circuit, the emitter of each first transistor is also connected to a current limiting circuit, and the collector of each first transistor is connected to the interior light LED array.
[0030] Combine Figure 4 The microcontroller unit also outputs PWM signals with different duty cycles to the reading light adjustment unit. Two reading light adjustment units are provided, connected to pins 21 and 43 of the microcontroller unit, respectively. Each reading light adjustment unit includes a second transistor, a constant current circuit, a current limiting circuit, and a reading light LED array. The constant current circuit is connected to the base of the second transistor, the current limiting circuit is connected to the emitter of the second transistor, and the reading light LED array is connected to the collector of the second transistor.
[0031] In this embodiment, the micro control unit is also connected to the indoor light backlight adjustment unit and the reading light backlight adjustment unit. Figure 5 The microcontroller unit also outputs PWM signals with different duty cycles to the interior light backlight adjustment unit; the interior light backlight adjustment unit is connected to pins 29, 30, 31, 33, 34, and 35 of the microcontroller unit, respectively. The interior light backlight adjustment unit includes three third transistors connected in parallel, each of which has a base connected to a constant current circuit; each of which has an emitter connected to a current limiting circuit; and each of which has a collector connected to an interior light backlight LED array. A fifth resistor is also connected in series between the collector of each of the third transistors and the interior light backlight LED array.
[0032] Further, combined Figure 6 The reading light backlight adjustment unit is respectively connected to pins 26, 27, 28, 36, 37, and 38 of the microcontroller unit. The reading light backlight adjustment unit includes three fourth transistors connected in parallel, the base of each fourth transistor being connected to a constant current circuit; the emitter of each fourth transistor being connected to a current limiting circuit; the collector of each fourth transistor being connected to the reading light backlight LED array; and three sixth resistors being connected in parallel between the collectors of the fourth transistors and the reading light backlight LED array.
[0033] In this embodiment, both the interior light backlight LED array and the reading light backlight LED array include three primary color LED lamps. By outputting PWM signals with different duty cycles, the proportion of different color lights is adjusted, thereby achieving multi-range color selection and switching.
[0034] In this embodiment, one end of a constant current circuit is connected to a pin of a microcontroller unit, and the other end is connected to the base of a transistor. The constant current circuit includes a first resistor, a second resistor connected to one end of the first resistor, a capacitor, and a Zener diode. The second resistor, capacitor, and Zener diode are connected in parallel, with their other ends grounded. Using this constant current circuit to drive an LED array ensures a constant current output, resulting in stable brightness for the LED array.
[0035] The current limiting circuit includes a third resistor and a fourth resistor connected in parallel. One end of each resistor is connected to the emitter of the transistor, and the other end is grounded. This current limiting circuit effectively prevents excessive current in the circuit from damaging circuit components, further effectively protecting the circuit.
[0036] Working principle:
[0037] By touching the capacitive touch film, the signal is transmitted to the touch unit, and the touch unit transmits the above signal to the microcontroller unit. The microcontroller unit outputs PWM signals with different duty cycles to control the on and off of the transistors in the interior light adjustment unit and the reading light adjustment unit, thereby realizing multi-range brightness adjustment of the interior light and the reading light. By controlling the on and off of the transistors in the interior light backlight adjustment unit and the reading light backlight adjustment unit, the color and brightness adjustment of the interior light backlight and the reading light backlight can be realized.
[0038] Although the above description of the specific implementation methods of the present invention is combined with the accompanying drawings, it does not limit the scope of protection of the present invention. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present invention, various modifications or deformations that can be made by technical personnel in this field without creative work are still within the scope of protection of the present invention.
Claims
1. A PWM-based automobile interior light dimming circuit, characterized in that: It includes a touch control unit and an interior light adjustment unit; both the touch control unit and the interior light adjustment unit are connected to the micro control unit; The microcontroller unit outputs PWM signals with different duty cycles to the indoor light adjustment unit; the indoor light adjustment unit includes a plurality of first transistors connected in parallel, the base of each first transistor is connected to the first constant current circuit, the emitter of each first transistor is also connected to the current limiting circuit, and the collector of the first transistor is connected to the indoor light LED array.
2. A PWM-based automobile interior light dimming circuit as claimed in claim 1, characterized in that: One end of the constant current circuit is connected to the pin of the micro control unit, and the other end is connected to the base of the transistor; the constant current circuit includes a first resistor and a second resistor connected to one end of the first resistor, a capacitor and a voltage-stabilizing diode, wherein the second resistor, the capacitor and the voltage-stabilizing diode are connected in parallel and the other end is grounded.
3. The PWM-based automobile interior light dimming circuit according to claim 1, characterized in that: The current limiting circuit includes a third resistor and a fourth resistor connected in parallel with each other. One end of the third resistor and the fourth resistor is connected to the emitter of the transistor, and the other end is grounded.
4. The PWM-based automobile interior light dimming circuit according to claim 1, characterized in that: It also includes an interior light backlight adjustment unit, which is used to adjust the interior light backlight LED. The interior light backlight LED is arranged around the interior light of the car. The micro control unit also outputs PWM signals with different duty cycles to the interior light backlight adjustment unit.
5. The PWM-based automobile interior light dimming circuit according to claim 4, characterized in that: The indoor light backlight adjustment unit includes three third transistors connected in parallel, the base of each third transistor is connected to the constant current circuit; the emitter of each third transistor is connected to the current limiting circuit, the collector of each third transistor is connected to the indoor light backlight LED array, and a fifth resistor is also connected in series between the collector of the third transistor and the indoor light backlight LED array.
6. The PWM-based automobile interior light dimming circuit according to claim 1, characterized in that: The PWM-based automobile interior light dimming circuit further includes a reading light adjustment unit, and the microcontroller unit further outputs PWM signals with different duty cycles to the reading light adjustment unit.
7. A PWM-based automobile interior light dimming circuit as claimed in claim 6, characterized in that: The reading light adjustment unit is set to two, each reading light adjustment unit includes a second transistor, a constant current circuit, a current limiting circuit and a reading light LED array; wherein the constant current circuit is connected to the base of the second transistor, the current limiting circuit is connected to the emitter of the second transistor, and the reading light LED array is connected to the collector of the second transistor.
8. The PWM-based automobile interior light dimming circuit according to claim 1, characterized in that: It also includes a reading light backlight adjustment unit, which is used to adjust the reading light backlight LED. The reading light backlight LED is arranged around the car reading light. The micro control unit also outputs PWM signals with different duty cycles to the reading light backlight adjustment unit.
9. The PWM-based automobile interior light dimming circuit according to claim 1, characterized in that: The reading light backlight adjustment unit includes three fourth transistors connected in parallel, the base of each fourth transistor is connected to the constant current circuit; the emitter of each fourth transistor is connected to the current limiting circuit, and the collector of each fourth transistor is connected to the reading light backlight LED array.
10. The PWM-based automobile interior light dimming circuit according to claim 9, characterized in that: Three sixth resistors are further connected between the collector of the fourth transistor and the reading light backlight LED array, and the sixth resistors are connected in parallel.