Lamp control device
AssigneeRohm Co., Ltd.
InventorMasaaki Nakayama
Life of this patent
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Abstract
A lamp control device comprises a first input terminal, a second input terminal, an output terminal that is configured to be connectable to a lamp via an external switch and outputs a drive current for the lamp, an internal switch provided on a first path connecting the first input terminal and the output terminal, a constant current section provided on a second path connecting the second input terminal and the output terminal, a voltage monitoring section that monitors a voltage applied to the output terminal, and a control section that controls the internal switch on the basis of a monitoring result from the voltage monitoring section.
Claims13
A lamp control device comprising:
- a first input terminal;
- a second input terminal;
- an output terminal configured to be connectable to a lamp via an external switch, a driving current for the lamp being output via the output terminal;
- an internal switch arranged on a first path connecting together the first input terminal and the output terminal;
- a constant current circuit arranged on a second path connecting together the second input terminal and the output terminal;
- a voltage monitor configured to monitor a voltage fed to the output terminal;
- and
- a controller configured to control the internal switch based on a result of monitoring by the voltage monitor,
- wherein the controller is configured to start switching alternately between first and second control modes when the voltage fed to the output terminal is lower than a first predetermined value.
A lamp system comprising:
- a lamp control device;
- an external switch;
- a lamp;
- and
- first and second resistors,
- wherein the lamp control device comprises:
- a first input terminal;
- a second input terminal;
- an output terminal configured to be connectable to the lamp via the external switch, a driving current for the lamp being output via the output terminal;
- an internal switch arranged on a first path connecting together the first input terminal and the output terminal;
- a constant current circuit arranged on a second path connecting together the second input terminal and the output terminal;
- a voltage monitor configured to monitor a voltage fed to the output terminal;
- and
- a controller configured to control the internal switch based on a result of monitoring by the voltage monitor,
- wherein the lamp system is operable such that an input voltage is fed to one terminal of the first resistor and to one terminal of the second resistor,
- another terminal of the first resistor is connected to the first input terminal,
- another terminal of the second resistor is connected to the second input terminal, and
- a resistance value of the second resistor is higher than a resistance value of the first resistor.
Dependencies are inferred from the claim text.