Light emitting circuit and lighting device

• US 6,897,614 B2
• Filed: 11/28/2002
• Issued: 05/24/2005
• Est. Priority Date: 02/20/2002
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Yoshioka, Isamu, Matsumoto, Masatomo, Ishizaki, Masaru
• Primary Examiner(s): Philogene, Haissa
• Application Number:
  US10/363,582
• Publication Number:
  US 20030179583A1
• Time in Patent Office: 908 Days
• Field of Search: 315/77, 315/84, 340/425.5, 340/468, 340/469, 340/472, 307/9.1, 307/10.1, 307/10.8, 362/494, 362/498, 362/543, 362/545, 362/800
• US Class Current: 315/84
• CPC Class Codes: B60Q 1/2665 on rear-view mirrors lighting devices for vehicle interior on or for rear-view mirrors B60Q3/258
• CPC Class Codes: B60Q 1/34 for indicating change of drive direction B60Q1/22 takes precedence
• CPC Class Codes: B60Q 11/007 the lighting devices indicating change of drive direction
• CPC Class Codes: B60R 1/1207 with lamps; with turn indicators
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 47/20 Responsive to malfunctions or to light source life; for protection

Abstract

A light emitting circuit includes: a first circuit H1 in which is provided a main light source 5, 6; and a second circuit H2 connected in parallel with the first circuit H1 and in which is provided an auxiliary light source 1, 2 and 3; wherein a drain (D) and a source (S) of an field effect transistor 4 are connected in the second circuit H2, and a gate (G) of the field effect transistor 4 is connected to the first circuit H1.

Claims

1. A light emitting circuit comprising:

a first circuit in which is provided a main light source; and

a second circuit connected in parallel with the first circuit and in which is provided an auxiliary light source;

wherein a drain and a source of an field effect transistor are connected in the second circuit, and a gate of the field effect transistor is connected to the first circuit;

wherein if the main light source runs down such that a voltage at the gate falls below a threshold voltage, current does not flow through the auxiliary light source.

2. A light emitting circuit according to claim 1, wherein said main light source emits light at a luminance higher than said auxiliary light source.

3. A light emitting circuit for a vehicle according to claim 1, wherein if the auxiliary light source runs down, current is not prevented from running through the main light source.

4. A light emitting circuit for a vehicle according to claim 1, wherein if the main light source runs down, the voltage at the gate of the field effect transistor becomes zero.

5. A lighting device for a vehicle, which is provided in an outer mirror of a vehicle, comprising:

a main light source arranged at a side of the outer mirror;

an auxiliary light source arranged at a front of the outer mirror; and

a light emitting circuit having a first circuit in which is provided the maim light source, and a second circuit connected in parallel with the first circuit and in which is provided the auxiliary light source, wherein a drain and a source of an field effect transistor are connected in the second circuit, and a gate of the field effect transistor is connected to the first circuit;

wherein if the main light source runs down such that a voltage at the gate falls below a threshold voltage, current does not flow through the auxiliary light source.

6. A lighting device for a vehicle according to claim 5, wherein said main light source emits light at a luminance higher than said auxiliary light source.

7. A lighting device for a vehicle according to claim 5, wherein said outer mirror is a door mirror.

8. A lighting device for a vehicle according to claim 6, wherein said outer mirror is a door mirror.

9. A lighting device for a vehicle, which is provided in an outer mirror of a vehicle, comprising:

a main light source arranged at a side of the outer mirror;

an auxiliary light source arranged at a front of the outer mirror; and

a light emitting circuit having a first circuit in which is provided the main light source, and a second circuit connected in parallel with the first circuit and in which is provided the auxiliary light source, wherein an emitter and a collector of a bipolar transistor are connected in the second circuit, and a base of the bipolar transistor is connected to the first circuit;

wherein if the main light source runs down such that a voltage at the base of the bipolar transistor falls below a threshold voltage, current does not flow through the auxiliary light source.

10. A lighting device for a vehicle according to claim 9, wherein said outer mirror is a door mirror.

11. A lighting device for a vehicle according to claim 9, wherein said main light source emits light at a luminance higher than said auxiliary light source.

12. A light emitting circuit comprising:

a first circuit in which is provided a main light source; and

a second circuit connected in parallel with the first circuit and in which is provided an auxiliary light source;

wherein an emitter and a collector of a bipolar transistor are connected in the second circuit, and a base of the bipolar transistor is connected to the first circuit;

wherein if the main light source runs down such that a voltage at the base of the bipolar transistor falls below a threshold voltage, current does not flow through the auxiliary light source.

13. A light emitting circuit for a vehicle according to claim 12, wherein if the auxiliary light source runs down, current is not prevented from running through the main light source.

14. A light emitting circuit according to claim 12, wherein said main light source emits light at a luminance higher than said auxiliary light source.

15. A light emitting circuit for a vehicle according to claim 12, wherein if the main light source runs down, the voltage at the base of the bipolar transistor becomes zero.