Non-contact information storage medium and data transmission method for the medium
First Claim
1. A non-contact information storage medium for receiving power from a received radio wave from outside of the medium, and transmitting data in a form of a transmission wave to the outside, comprising:
- an antenna for obtaining power from a received radio wave;
a rectifier circuit for converting the power obtained by the antenna into a power current for powering a circuit incorporated in the medium;
a switching circuit connected to an output of the rectifier circuit for switching on and off a current path from the rectifier circuit in accordance with the transmission wave;
a smoothing capacitor connected to the output of the rectifier circuit through the switching circuit for accumulating the output current of the rectifier circuit and smoothing an output voltage; and
a voltage stabilizing circuit connected to the smoothing capacitor for keeping at a constant value a charge voltage of the smoothing capacitor.
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Accused Products
Abstract
A non-contact information storage medium for receiving power from a card reader/writer via an antenna, using the power for driving its internal circuit, and simultaneously transmitting data as a transmission wave to the outside thereof. The output current of a rectifier circuit is interrupted by a switching circuit incorporated in a modulation circuit in accordance with the transmission wave. In the period of interruption, the output voltage of the rectifier circuit is limited by a voltage limiting circuit incorporated in the modulation circuit to a value not more than the breakdown voltage of elements which constitute the circuit. The loss of power during data transmission is extremely small, and hence the circuit can be constituted by elements of a usual breakdown voltage.
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Citations
10 Claims
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1. A non-contact information storage medium for receiving power from a received radio wave from outside of the medium, and transmitting data in a form of a transmission wave to the outside, comprising:
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an antenna for obtaining power from a received radio wave; a rectifier circuit for converting the power obtained by the antenna into a power current for powering a circuit incorporated in the medium; a switching circuit connected to an output of the rectifier circuit for switching on and off a current path from the rectifier circuit in accordance with the transmission wave; a smoothing capacitor connected to the output of the rectifier circuit through the switching circuit for accumulating the output current of the rectifier circuit and smoothing an output voltage; and a voltage stabilizing circuit connected to the smoothing capacitor for keeping at a constant value a charge voltage of the smoothing capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification