Lighting control apparatus for vehicle lighting device

Abstract

A lighting control apparatus and a method of lighting control for a vehicle lighting device includes a semiconductor light source including a semiconductor light emitting element; and a current supply controller coupled between a power supply and the semiconductor light source. Supply of a current from the power supply to the semiconductor light source is restricted by the current supply controller during a current restriction period to a value smaller than a prescribed current. A microcomputer compares a forward voltage generated from the semiconductor light source during the current restriction period with an abnormality determination value to determine whether or not an abnormality occurs due to a change of the forward voltage of the semiconductor light source.

Description

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a circuit diagram of the lighting control apparatus for a vehicle lighting device according to the first embodiment of the invention.

FIG. 2 is a circuit diagram of a switching regulator.

FIG. 3 is a circuit diagram of a control circuit.

FIG. 4 shows waveform diagrams for explaining the operation of the control circuit

FIG. 5 is a circuit diagram of a control power supply.

FIG. 6 is a circuit diagram of a forward voltage detection circuit.

FIG. 7( a) is a characteristic diagram for explaining the Vf—If characteristics of an LED and an multichip LED in the case where an abnormality occurs in one LED, and FIG. 7(b) is a characteristic diagram for explaining the Vf—If characteristics of an LED and an multichip LED in the case where an abnormality occurs in two LEDs.

FIG. 8 is a circuit diagram for explaining the relation between a current restriction period setting circuit and the control circuit

FIG. 9 is a circuit diagram of the main portion of the lighting control apparatus for a vehicle lighting device according to the second embodiment of the invention.

FIG. 10 is a circuit diagram for explaining the relation among the control power supply, the switching regulator and a power supply limit circuit.

FIG. 11 is a circuit diagram for explaining the relation between the control power supply and the power supply limit circuit.

Claims

1. A lighting control apparatus for a vehicle lighting device, comprising: current supply control means for controlling supply of a current to a semiconductor light source including a semiconductor light emitting element;current restriction period setting means for setting, to the current supply control means, a period for restricting the current to be supplied to the semiconductor light source to a value smaller than a prescribed current; anddetermination means for comparing a forward voltage generated from the semiconductor light source during the period set by the current restriction period setting means with an abnormality determination value to determine whether or not an abnormality occurs due to a change of the forward voltage of the semiconductor light source.

2. A lighting control apparatus for a vehicle lighting device, comprising: current supply control means for controlling supply of a current to a semiconductor light source including a semiconductor light emitting element and a static electricity protection element coupled in parallel to the semiconductor light emitting element;current restriction period setting means for setting, to the current supply control means, a period for restricting the current to be supplied to the semiconductor light source to a value smaller than a prescribed current; anddetermination means for comparing a forward voltage generated from the semiconductor light source during the period set by the current restriction period setting means with an abnormality determination value to determine whether or not an abnormality occurs due to a change of the forward voltage of the semiconductor light source.

3. A lighting control apparatus for a vehicle lighting device, comprising: current supply control means for controlling supply of a current to a semiconductor light source including a semiconductor light emitting element and a static electricity protection element coupled in parallel to the semiconductor light emitting element;starting stop period setting means for setting, to the current supply control means, a starting stop period during which a supply of a current to the semiconductor light source is stopped;auxiliary current supply means for supplying, during the starting stop time period, to the semiconductor light source, a current that flows through the static electricity protection element in a forward direction and flows through the semiconductor light emitting element in a backward direction and is smaller than a prescribed current; anddetermination means for comparing a forward voltage generated from the semiconductor light source during the starting stop period with an abnormality determination value to determine whether or not an abnormality occurs due to a change of the forward voltage of the semiconductor light source.

4. A lighting control apparatus for a vehicle lighting device according to claim 1, wherein the abnormality determination value is a value set based on a forward voltage when a forward current of the semiconductor light emitting element is in a region smaller than the prescribed current.

5. A lighting control apparatus for a vehicle lighting device according to claim 3, wherein the abnormality determination value is a value set based on a forward voltage when a forward current of the static electricity protection element is in a region smaller than the prescribed current.

6. A lighting control apparatus for a vehicle lighting device according to claim 2, wherein the abnormality determination value is a value set based on a forward voltage when a forward current of the semiconductor light emitting element is in a region smaller than the prescribed current.

7. A lighting control apparatus for a vehicle lighting device according to claim 1, wherein the current supply control means supplies a current to a plurality of semiconductor light sources each including a semiconductor light emitting element.

8. A lighting control apparatus for a vehicle lighting device according to claim 2, wherein the current supply control means supplies a current to a plurality of semiconductor light sources each including a semiconductor light emitting element.

9. A lighting control apparatus for a vehicle lighting device according to claim 3, wherein the current supply control means supplies a current to a plurality of semiconductor light sources each including a semiconductor light emitting element.

10. A lighting control apparatus for a vehicle lighting device, comprising: a semiconductor light source including a semiconductor light emitting element;a current supply controller coupled between a power supply and the semiconductor light source,wherein supply of a current from the power supply to the semiconductor light source is restricted by the current supply controller during a current restriction period to a value smaller than a prescribed current; anda microcomputer that compares a forward voltage generated from the semiconductor light source during the current restriction period with an abnormality determination value to determine whether or not an abnormality occurs due to a change of the forward voltage of the semiconductor light source.

11. A lighting control apparatus for a vehicle lighting device according to claim 10, wherein the abnormality determination value is a value set based on a forward voltage when a forward current of the semiconductor light emitting element is in a region smaller than the prescribed current.

12. A lighting control apparatus for a vehicle lighting device, comprising: a semiconductor light source including a semiconductor light emitting element and a static electricity protection element coupled in parallel to the semiconductor light emitting element;a current supply controller coupled between a power supply and the semiconductor light source;wherein supply of a current to the semiconductor light source is restricted during a restriction period to a value smaller than a prescribed current; anda microcomputer that compares a forward voltage generated from the semiconductor light source during the current restriction period with an abnormality determination value to determine whether or not an abnormality occurs due to a change of the forward voltage of the semiconductor light source.

13. A lighting control apparatus for a vehicle lighting device according to claim 12, wherein the abnormality determination value is a value set based on a forward voltage when a forward current of the semiconductor light emitting element is in a region smaller than the prescribed current.

14. A lighting control apparatus for a vehicle lighting device, comprising: a semiconductor light source including a semiconductor light emitting element and a static electricity protection element coupled in parallel to the semiconductor light emitting elementa current supply controller coupled between a power supply and the semiconductor light source;an auxiliary current supply circuit coupled between the power supply and the semiconductor light source,wherein during a stop period supply of a current from the current supply controller to the semiconductor light source is stopped, andwherein during the stop period supply of a current from the auxiliary current supply circuit that flows through the static electricity protection element in a forward direction, flows through the semiconductor light emitting element in a backward direction, and is smaller than a prescribed current is supplied; anda microcomputer that compares a forward voltage generated from the semiconductor light source during the stop period with an abnormality determination value to determine whether or not an abnormality occurs due to a change of the forward voltage of the semiconductor light source.

15. A lighting control apparatus for a vehicle lighting device according to claim 14, wherein the abnormality determination value is a value set based on a forward voltage when a forward current of the static electricity protection element is in a region smaller than the prescribed current.

16. A method of lighting control for a vehicle lighting device including a semiconductor light source, the method comprising: restricting supply of a current from a power supply to the semiconductor light source during a current restriction period to a value smaller than a prescribed current; andcomparing a forward voltage generated from the semiconductor light source during the current restriction period with an abnormality determination value to determine whether or not an abnormality occurs due to a change of the forward voltage of the semiconductor light source.

17. The method of lighting control for a vehicle lighting device according to claim 16, further comprising setting the abnormality determination value based on a forward voltage when a forward current of the semiconductor light emitting element is in a region smaller than the prescribed current.

18. A method of lighting control for a vehicle lighting device including a semiconductor light emitting element and a static electricity protection element coupled in parallel to the semiconductor light emitting element, the method comprising: stopping, during a stop period, supply of a current to the semiconductor light source, andsupplying, during the stop period, an auxiliary current that flows through the static electricity protection element in a forward direction, flows through the semiconductor light emitting element in a backward direction, and is smaller than a prescribed current is supplied; andcomparing a forward voltage generated from the semiconductor light source during the stop period with an abnormality determination value to determine whether or not an abnormality occurs due to a change of the forward voltage of the semiconductor light source.

19. The method of lighting control for a vehicle lighting device according to claim 18, further comprising setting the abnormality determination value based on a forward voltage when a forward current of the static electricity protection element is in a region smaller than the prescribed current.