Transmission Device, Keyless Entry System, and Tire Pneumatic Pressure Monitoring System
First Claim
Patent Images
1. A transmission device comprising:
- a transmission antenna portion;
an output portion having a first switch and a second switch connected in series between two different potentials, an output current fed to the transmission antenna portion being derived from a node between the first and second switches;
an output driving portion controlling turning-on and -off of the first and second switches; and
duty ratio setting means for variably setting a duty ratio at which the output driving portion drives the first and second switches.
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Abstract
According to the invention, a transmission device has a transmission antenna portion, an output portion that has a first switch and a second switch connected in series between two different potentials and that derives from the node between the first and second switches an output current fed to the transmission antenna portion, an output driving portion that controls turning-on and -off of the first and second switches, and duty ratio setting means for variably setting the duty ratio at which the output driving portion drives the first and second switches. The invention makes it possible to adjust the radiowave coverage area of the transmission antenna portion easily without complicated work.
15 Citations
10 Claims
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1. A transmission device comprising:
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a transmission antenna portion; an output portion having a first switch and a second switch connected in series between two different potentials, an output current fed to the transmission antenna portion being derived from a node between the first and second switches; an output driving portion controlling turning-on and -off of the first and second switches; and duty ratio setting means for variably setting a duty ratio at which the output driving portion drives the first and second switches. - View Dependent Claims (2, 3, 4)
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5. A transmission device comprising:
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a transmission antenna portion; an output portion having a first switch and a second switch connected in series between two different potentials, an output current fed to the transmission antenna portion being derived from a node between the first and second switches; and an output driving portion controlling turning-on and -off of the first and second switches according to a first control signal; wherein the first and second switches are each a switch element group composed of a plurality of switch elements connected in parallel with one another, and, according to a second control signal, the output driving portion selects, from the plurality of switch elements, switch elements whose turning-on and -off is controlled according to the first control signal. - View Dependent Claims (6, 7, 8, 9, 10)
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Specification