LED lamp apparatus for vehicles

• US 20030117088A1
• Filed: 12/18/2002
• Published: 06/26/2003
• Est. Priority Date: 12/19/2001
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Tanabe, Tetsuo, Tauchi, Shigeaki
• Granted Patent: US 6,870,328 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: B60Q 1/1407 General lighting circuits comprising dimming circuits
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/40 Details of LED load circuits
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices

Abstract

In an LED unit, all of eight LEDs are connected in series. The voltage of a power supply, that is, a battery of a vehicle, 12 V, is insufficient for the eight LEDs. To cope with this, a boosting circuit is provided within the control unit to boost the voltage to about 16 V which is then applied to the eight LEDs. The front end of the LED unit is connected to a constant-current circuit, and a voltage detection circuit is provided near and connected to this constant-current circuit for detecting the voltage applied to the constant-current circuit. The voltage detected by the voltage detection circuit is compared with a reference voltage drawn from the power supply, is amplified in an amplifier, and is input as a boosting control signal into the boosting circuit. The boosting control signal is output so as to regulate the boosted voltage in such a manner that the voltage detected in the voltage detection circuit is a lowest possible voltage.

Claims

1. An LED lamp apparatus for vehicles, comprising:

a light source including a predetermined number of light emitting diodes connected in series to each other or one another; and

a power supply of a predetermined voltage to be applied across the predetermined number of light emitting diodes, the predetermined voltage being dependent on the predetermined number of light emitting diodes.

2. The LED lamp apparatus for vehicles according to claim 1, wherein:

the power supply of the predetermined voltage, comprises;

a booster for boosting a voltage of a primary power supply to the predetermined voltage.

3. The LED lamp apparatus for vehicles according to claim 2, wherein:

the power supply of the predetermined voltage, comprises;

a circuit for adjusting the predetermined voltage to a voltage dependent on a current flowing through the predetermined number of light emitting diodes.

4. A rear combination lamp apparatus for vehicles, comprising, as a light source, a plurality of light emitting diodes connected to each other or one another in series, a voltage boosted from a power supply voltage being applied to the plurality of light emitting diodes for lighting.

5. The rear combination lamp apparatus for vehicles according to claim 4, wherein the light emitting diodes connected in series are driven at a constant current and a variable voltage is applied to the light emitting diodes.

6. The rear combination lamp apparatus for vehicles according to claim 5, wherein a circuit for the voltage boosted from the power supply voltage comprises a constant-current circuit and a voltage detection circuit for detecting the voltage applied to the constant-current circuit, and the variable voltage applied to the plurality of light emitting diodes is such that the voltage detected by the voltage detection circuit is a lowest possible voltage which can cause emission of light from the plurality of light emitting diodes.

7. An LED head lamp apparatus for vehicles, comprising, as a light source, a plurality of light emitting diodes connected to each other or one another in series, a voltage boosted from a power supply voltage being applied to the plurality of light emitting diodes for lighting.

8. The LED head lamp apparatus for vehicles according to claim 7, wherein the light emitting diodes connected in series are driven at a constant current and a variable voltage is applied to the light emitting diodes.

9. The LED head lamp apparatus for vehicles according to claim 8, wherein a circuit for the voltage boosted from the power supply voltage comprises a constant-current circuit and a voltage detection circuit for detecting the voltage applied to the constant-current circuit, and the variable voltage applied to the plurality of light emitting diodes is such that the voltage detected by the voltage detection circuit is a lowest possible voltage which can cause emission of light from the plurality of light emitting diodes.

10. The LED head lamp apparatus for vehicles according to claim 7, wherein an alternate circuit for current is provided in each of the light emitting diodes connected in series.

11. The LED head lamp apparatus for vehicles according to claim 8, wherein an alternate circuit for current is provided in each of the light emitting diodes connected in series.

12. The LED head lamp apparatus for vehicles according to claim 9, wherein an alternate circuit for current is provided in each of the light emitting diodes connected in series.