Automatic answering system using transponder
US5835010A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Nov 22, 1996 |
| Grant date | Nov 10, 1998 |
| Priority date | — |
| Expiry date | Nov 22, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C2009/00603
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
The power feeding efficiency and the communicable range of an automatic answering system are improved in an automatic answering system using a transponder which performs code communication using amplitude modulation of a carrier with an electromagnetic coupling transponder mounted in a key or the like. In a transceiver for performing the code communication with the transponder via an antenna coil, a circuit for driving the antenna coil in a transceiver based on clock is implemented by a bridge-type complementary circuit of transistors. Thereby, driving current is increased. Meanwhile, a circuit for controlling the driving mode based on a write signal is implemented by a parallel circuit of a transistor to which a power-supply voltage is applied and a resistor. Thereby, a current corresponding to a resistance of the resistor flows through the antenna coil even during the minimum driving when the transistor is turned off, thus improving the power feeding efficiency and the communicable range of the system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.