The composition of disposable vapes is relatively simple: e-liquid, cartridges, and batteries are all assembled, and the structure consists of a mold-opening shell, an atomizer, a battery, and a microphone head.
When it comes to the control system of e-cigarettes, the intuitive reaction of most people is that the PCB board (also known as the printed circuit board, which is the provider of the electrical connection of electronic components), wires, switches, and other components are combined according to specific requirements to form a system.
But strictly speaking, a complete control system includes not only the electronic circuit hardware system composed of the central controller, connecting wires, resistors, capacitors, inductors, etc., but also the programs used to perform various functional protection and control components to execute commands accurately Language, that is, the software part.
The hardware system is the basis of the electronic cigarette control system and has standard features, while the design of the programming language is often flexible and varied. For this consideration, this section only combines the hardware system of the electronic cigarette control system, focusing on the system composition. These electronic circuits realize various operation modes and functional protection.
The structure of the disposable electronic cigarette is simple, and its control system mainly manages and coordinates the pneumatic switch, atomizer, polymer lithium battery, and indicator light.
Most disposable vape kits use pneumatic switches, also known as airflow sensing switches, which are called flavor heads in the industry.
Structure and working principle of the pneumatic switch
The structure of the pneumatic switch is shown in the figure, which is mainly composed of a pole piece, a diaphragm, a gasket, a cavity, a shell, a PCB assembly, and an LED.
The pole piece and the diaphragm inside the pneumatic switch form a flat capacitor structure. When the airflow enters the cavity, the diaphragm starts to vibrate, causing the electric field at both ends of the capacitor to charge, generating a voltage signal that changes with the airflow and completing the airflow signal to the electrical signal. Transformation.
Working process of the pneumatic switch:
- When there is a suction action, the pneumatic controller detects the negative pressure generated by smoking.
- The internal output switch is turned on.
- The heating wire is heated.
- The e-liquid is atomized under the action of heat and emerges from the cigarette holder with the airflow.
The pneumatic switch has the following functions:
Detect battery voltage and continuously flash alarm when the voltage is low;
When smoking, control the LED light on;
After smoking, turn off the internal output switch, and the LED light will go out.
Description of integrated IC performance
In the pneumatic switch of the disposable electronic cigarette, to integrate the corresponding management function and put the control program, the chip programmed with the programming language and the pneumatic button are often integrated into an IC component, and the heating element driver and LED driver is often integrated inside. And charger circuit and ASIC design are adopted so that there will be no crash of the central controller scheme, nor the phenomenon that the chip cannot be reset due to lower than the critical voltage.
Function realization of the control module
The integrated IC of the disposable electronic cigarette contains a short circuit protection function (SCP), an Undervoltage protection function (UVLO), an overheat protection function (OTP), and an LED work indication function, which can effectively complete the parameter detection in the work of the electronic cigarette, and the control system is always It generally operates according to the set process parameters.
The following is a brief introduction of each functional module on the control board one by one:
Oscillator (OSC): The system integrates a clock control signal with a central oscillation frequency of 33KHz, which provides the required clock frequency for the system’s internal circuit to ensure the chip’s regular operation and the correctness of the indication function.
Protection control module: The chip integrates an under-voltage protection module (UVLO) to detect the power supply voltage of the system battery. When the operating voltage is lower than 3.1V, the UVL0 output enables valid; the short-circuit protection module (SCP) is used to indicate that the load resistance of the atomizing wire is less than 1Ω; the over-temperature protection module (OTP) is used to control the operating temperature of the system to prevent the chip from being shortened due to overheating of the system.
Airflow switch: The system integrates an airflow switch, which will generate a control signal when it detects that the negative pressure is more significant than a specific set value (about 300Pa). The sensitivity of the microphone heads produced by different manufacturers will be different to a certain extent, so the negative pressure value detected is not the same.
Charging module: Internal integrated charging management, the lithium battery can be charged by connecting the external voltage directly to 5V.
LED display module: status information indication, with gradual brightening and gradual fire effect and flickering function.
AT output module: integrated M lower output, directly connected to the heating element.
LOGIC control: Each system module is controlled by the central controller.