The payment principle of QR code scanning equipment mainly involves the identification and decoding of QR codes as well as the transmission and processing of payment information. Here is a detailed step-by-step explanation:

QR Code Recognition: 

First, the user generates a QR code containing payment information through the payment application. This QR code is usually displayed on the user's mobile phone screen. When a user points a QR code scanning device at the QR code, the optical sensor inside the scanning device emits light and scans the pattern on the QR code.

Decoding Process: 

After receiving the optical signal of the QR code, the code scanning device will perform decoding processing. The process involves identifying the black and white squares in the QR code and parsing out the payment information contained within them. This information may include payment amount, payee account, order number, etc.

Information Transmission: 

After decoding is completed, the QR code scanning device will transmit the parsed payment information to the connected cashier system or payment terminal. This is typically accomplished via wired or wireless means, depending on the type of interface between the scanning device and the cashier system or payment terminal.

Payment Processing: 

After payment information is received by the cashier system or payment terminal, further verification and processing will be performed. This may include checking that the payment amount is correct, that the payee's account is valid, etc. Once verified, the payment information will be sent to the payment gateway or bank for final processing.

Complete Payment: 

After the bank or payment gateway processes the payment information, it will send the payment result to the cashier system or payment terminal. If the payment is successful, the cashier system or payment terminal will display a payment success message and may print out a transaction voucher. If the payment fails, the appropriate error message will be displayed.

During the entire process, the QR code scanning device plays the role of quickly and accurately transmitting the payment information in the QR code to the cashier system or payment terminal, thereby achieving a convenient and efficient payment experience. At the same time, in order to ensure the security of payment, scanning devices and payment systems usually adopt a variety of security measures, such as encrypted transmission, verification of payment information, etc.