Quasi-resonant diode drive current source

• US 5,287,372 A
• Filed: 04/24/1992
• Issued: 02/15/1994
• Est. Priority Date: 04/24/1992
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Ortiz, Joe A.
• Primary Examiner(s): Epps, Georgia Y.
• Application Number:
  US07/873,464
• Time in Patent Office: 662 Days
• Field of Search: 372/38, 372/92, 372/25, 372/33
• US Class Current: 372/38.07
• CPC Class Codes: H01S 5/042 Electrical excitation ; Circuits therefor monolithically integrated laser drive components H01S5/0261
• CPC Class Codes: H01S 5/0428 for applying pulses to the laser
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence
• CPC Class Codes: H02M 3/155 using semiconductor devices only
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A quasi-resonant diode drive current source provides high power pulsed current that drives light emitting diodes, and the like. The pulsed output current of the quasi-resonant diode drive current source is sensed, and is regulated by a control loop to a level required by the light emitting diodes. In a specific embodiment of the invention, a zero-current-switched full wave quasi-resonant buck converter is described that provides a high amplitude pulsed output current required to drive light emitting pump diodes used in a solid state diode pumped laser. The use of a quasi-resonant converter as a pulsed current source provides a much higher conversion efficiency than conventional laser current sources. This higher efficiency results in less input power drawn from a power source and cooler operation, resulting in a higher reliability current source.

Claims

1. A current source comprising:

a power source;

a light emitting diode;

a quasi-resonant converter coupled between the power source and the light emitting diode for providing pulsed current to the light emitting diode;

sensing means for sensing current flowing through the light emitting diode; and

control means coupled to the sensing means for regulating the amplitude of the pulsed current supplied to the light emitting diode.

2. The current source of claim 1 wherein the quasi-resonant converter comprises a zero-current-switched full wave quasi-resonant buck converter.

3. The current source of claim 2 wherein the quasi-resonant converter comprises:

a switch transistor wherein a diode is coupled across said switch transistor;

a resonant inductor in series with said switch transistor;

a filter inductor connected in series with the light emitting diode and the current sensing means; and

a resonant capacitor and a catch diode coupled in parallel across said filter inductor and said light emitting diode.

4. A laser drive circuit comprising:

a charge supply;

charge storage means coupled to the charge supply for storing charge;

a plurality of light emitting diode arrays that each contain individual pluralities of light emitting diodes coupled to the charge storage means;

a plurality of diode driver circuits respectively coupled to the plurality of light emitting diode arrays, and wherein each of the plurality of diode driver circuits comprises a quasi-resonant diode drive pulsed current source.

5. The laser drive circuit of claim 4 wherein each quasi-resonant diode drive current source comprises:

a quasi-resonant converter coupled between the charge storage means and a selected one of the plurality of light emitting diode arrays for providing pulsed current to the light emitting diodes of the arrays;

sensing means for sensing current flowing through the selected light emitting diode array; and

control means coupled to the sensing means for regulating the amplitude of the pulsed current supplied to the selected light emitting diode array.

6. The laser drive circuit of claim 5 wherein the quasi-resonant converter comprises a zero-current-switched full wave quasi-resonant buck converter.

7. The laser drive circuit of claim 6 wherein the quasi-resonant converter comprises:

switching means coupled between the charge storage means and a selected one of the plurality of light emitting diode arrays;

a resonant inductor and a filter inductor serially coupled between the switching means and the selected one of the plurality of light emitting diode arrays;

a catch diode and a resonant capacitor coupled across the filter inductor and the selected one of the plurality of light emitting diode arrays.