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US 10,477,643 B2Granted
Lighting device and vehicle
AssigneePanasonic Intellectual Property Management Co., Ltd.
InventorsToshiaki Nakamura, Kazuya Kato, Kenichi Fukuda, Akihiro Kishimoto
Life of this patent
Estimating the term…
Abstract
An impedance adjustment circuit varies an impedance of a transistor, thereby adjusting an impedance of a current path. A second control circuit controls a drive circuit to turn on or off at least one switch device of the switch devices while the impedance adjustment circuit is increasing the impedance of the current path. The impedance adjustment circuit adjusts the impedance of the current path to the minimum value after the drive circuit switches the at least one switch device from off to on or from on to off.
Claims20
A lighting device, comprising:
- a power supply circuit that has a first output terminal and a second output terminal and that is configured to output a load current as a DC current from the first output terminal to the second output terminal;
- switch devices that are electrically connected in series between the first and second output terminals, each of the switch devices being electrically connected in parallel with one or more light sources to be lit by the load current flowing therethrough;
- a drive circuit that is configured to individually turn on and off the switch devices;
- an impedance adjustment circuit that has an impedance device between the first and second output terminals and an impedance device driving circuit configured to vary an impedance of the impedance device in a prescribed range, the impedance adjustment circuit being configured to vary the impedance of the impedance device, thereby adjusting an impedance of a current path from the first output terminal to the second output terminal;
- and
- a control circuit that is configured to control the drive circuit and the impedance adjustment circuit, the control circuit being configured to control the drive circuit to turn on or off a switching object including at least one switch device of the switch devices within a switching time that is a period of time in which the impedance adjustment circuit is increasing the impedance of the current path, respectively, wherein
- the control circuit is configured to
- make the switching time longer than a time taken by the switching object to respectively switch from off to on or from on to off when the impedance adjustment circuit turns on or off the switching object, and
- adjust the impedance of the current path to a minimum value of the prescribed range after an end of the switching time.
6 more elements
A lighting device, comprising:
- a power supply circuit that has a first output terminal and a second output terminal and that is configured to output a load current as a DC current from the first output terminal to the second output terminal;
- switch devices that are electrically connected in series between the first and second output terminals, each of the switch devices being electrically connected in parallel with a corresponding one or more light sources to be lit by the load current flowing therethrough;
- a drive circuit that is configured to individually turn on and off the switch devices;
- an impedance adjustment circuit that has an impedance device between the first and second output terminals and an impedance device driving circuit configured to vary an impedance of the impedance device in a range between minimum and maximum values, the impedance adjustment circuit being configured to vary the impedance of the impedance device, thereby adjusting an impedance of a current path from the first output terminal to the second output terminal;
- and
- a control circuit that is configured to control the drive circuit, the control circuit being configured to control the drive circuit to turn on or off a switching object including at least one switch device of the switch devices within a switching time that is a period of time in which the impedance adjustment circuit is increasing the impedance of the current path, respectively, wherein
- the impedance adjustment circuit is configured to
- make the switching time longer than a time taken by the switching object to respectively switch from off to on or from on to off when the control circuit turns on or off the switching object, and
- adjust the impedance of the current path to the minimum value after an end of the switching time.
6 more elements
Dependencies are inferred from the claim text.