| 主权项 |
1. A payment card to facilitate a financial transaction between a customer and a merchant and to perform a functionality without external power source, comprising:
a card body; electronic circuitry attached to the card body, the electronic circuitry including a first electronic device configured to operate while the payment card is connected to a card reader of a merchant terminal of the merchant by using power provided by the card reader during a period of time when the customer inserts the payment card into the card reader, the electronic circuitry further including a second electronic device configured to perform the functionality of the payment card without external power source while the payment card is not connected with any card reader after the customer removes the payment card from the card reader, the electronic circuitry being configured to draw an amount of current from the card reader that is greater than an amount of current required to power the first electronic device; a rechargeable energy storage device attached to the card body and configured to supply electrical current to power the second electronic device when the payment card is not coupled to any card reader, wherein the rechargeable energy storage device is charged by at least a portion of the current drawn from the card reader; a reader interface attached to the card body and configured to connect with the card reader, through which to draw an electrical current from the card reader when the payment card is connected with the card reader so that the first electronic device operates and the rechargeable energy storage device is charged using the electrical current; a current limiter configured to impose an upper limit on the electrical current drawn from the card reader, the upper limit being greater than the amount of current required to power the first electronic device, such that a first portion of the electrical current drawn from the card reader is used to power the first electronic device when the payment card is connected with the card reader; and a charging circuit configured to charge the rechargeable energy storage device, when the payment card is connected with the card reader, from a second portion of the electrical current that is not used to power the electronic circuitry when the payment card is connected with the card reader. |
