Flyback as LED driver

• US 6,304,464 B1
• Filed: 07/06/2000
• Issued: 10/16/2001
• Est. Priority Date: 07/07/1999
• Status: Expired due to Term

• Current Assignee: Signify North America Corporation (Signify N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Hontele, Bertrand J. E., Nijhof, Engbert B. G., Bucks, Marcel J. M., Jacobs, Ronny A. A. M., De Clercq, John E. K. G.
• Primary Examiner(s): PATEL, RAJNIKANT B
• Application Number:
  US09/610,717
• Time in Patent Office: 467 Days
• Field of Search: 363/21, 363/20, 363/56, 363/97, 363/98, 363/131, 363/132, 315/205, 315/226, 315/169.3
• US Class Current: 363/21.12
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The invention relates to a circuit arrangement for operating a semiconductor light source, comprising

input terminals for connecting a supply voltage,

input filter means,

a converter provided with a switching element having a control circuit, and provided with inductive means, and

output terminals for connecting the semiconductor light source.

The switching element is periodically driven into conduction for a period t_on. According to the invention, the converter is formed by a flyback converter, and the inductive means are formed by a transformer, and the control circuit controls the t_on.

Claims

1. A circuit arrangement for operating a semiconductor light source, comprising:

a. input terminals for electrically connecting a source of AC power having a period T;

b. a filter electrically connected to the input terminals;

c. a flyback converter electrically connected to the filter and including a transformer electrically connected to a switching element;

d. a control circuit for periodically effecting switching of the switching element into a conducting state having a period t_on and for adjusting the duration of said period in response to variations in an ambient condition over an integration period which is substantially longer than T; and

e. output terminals for electrically connecting the circuit arrangement to the semiconductor light source.

2. A circuit arrangement as claimed in claim 1 where the ambient condition is ambient temperature.

3. A circuit arrangement as claimed in claim 1 where, in the operating state, the converter is operated in the critical mode.

5. A signal light arrangement as claimed in claim 1 comprising an integral housing for the semiconductor light source and the circuit arrangement.

4. A circuit arrangement as claimed in claim where the integration period is at least 2.5 T.

6. A signal light arrangement comprising a semiconductor light source and a circuit arrangement for operating said semiconductor light source, comprising:

a. input terminals for electrically connecting a source of AC power having a period T;

b. a filter electrically connected to the input terminals;

c. a flyback converter electrically connected to the filter and including a transformer electrically connected to a switching element;

d. a control circuit for periodically effecting switching of the switching element into a conducting state having a period t_on and for adjusting the duration of said period in response to variations in an ambient condition over an integration period which is substantially longer than T; and

e. output terminals for electrically connecting the circuit arrangement to the semiconductor light source.

7. A circuit arrangement as claimed in claim 6 where the ambient condition is ambient temperature.