Lighting device for vehicle

• US 20050162858A1
• Filed: 01/21/2005
• Published: 07/28/2005
• Est. Priority Date: 01/23/2004
• Status: Active Grant

• Current Assignee: Koito Manufacturing Company Limited
• Original Assignee: Koito Manufacturing Company Limited
• Inventors: Ito, Masayasu, Tsuchiya, Toshiyuki, Shiotsu, Fuminori
• Granted Patent: US 7,105,945 B2
• Time in Patent Office: Days
• US Class Current: 362/509
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output

Abstract

A lighting device for a vehicle comprises: a plurality of light source sections connected in parallel with each other; and a transformer for supplying an electric power to the plurality of light source sections. The transformer includes a primary coil and a plurality of secondary coils provided corresponding to the plurality of light source sections, for respectively supplying electric power to the corresponding light source sections. One end of each light source section is grounded and a semiconductor light emitting element is provided between one end and the other end of the light source section. The lighting device further comprises: a voltage detecting section for detecting voltages at the other ends of the plurality of light sources; and an output control section for controlling an electric current outputted from the transformer according to the voltage detected by the voltage detecting section.

Claims

1. A lighting device for a vehicle comprising:

a plurality of light source sections connected in parallel with each other; and

a transformer for supplying an electric power to the plurality of light source sections, the transformer including a primary coil, and a plurality of secondary coils provided corresponding to the plurality of light source sections, for respectively supplying the electric power to the corresponding light source sections.

2. A lighting device for a vehicle according to claim 1, wherein each of the light source sections includes a semiconductor light emitting element provided between one end and the other end of the light source section, and said one end of each light source section is grounded, and

said lighting device further comprising:

a voltage detecting section for detecting a voltage at said other ends of the plurality of light source sections; and

an output control section for controlling an electric current outputted from the transformer according to the voltage detected by the voltage detecting section,

wherein the output control section stops an output of the transformer in the case where the voltage at said other end in either light source section becomes lower than a previously set value.

3. A lighting device for a vehicle according to claim 2, further comprising:

a plurality of series resistors provided corresponding to the respective light source sections, respectively connected in series to the corresponding light source sections on one end side which is grounded,

wherein the output control section controls an output voltage of the transformer so that a voltage generated at both end portions of the series resistor can be equal to a setting voltage commonly determined with respect to the plurality of series resistors.

4. A lighting device for a vehicle according to claim 2, wherein the voltage detecting section detects an average value of the voltages at the respective other ends as the voltage at the other ends of the plurality of light source sections.

5. A lighting device for a vehicle according to claim 2, wherein the voltage detecting section detects the lowest voltage in the voltages of the other ends as the voltage of the other ends of the plurality of light source sections.