Soft start control circuit for lighting

• US 7,541,751 B2
• Filed: 03/05/2007
• Issued: 06/02/2009
• Est. Priority Date: 03/05/2007
• Status: Expired due to Fees

• Current Assignee: MDL Corporation
• Original Assignee: MDL Corporation
• Inventors: Vaziri, Ali
• Primary Examiner(s): Vu; David Hung
• Assistant Examiner(s): Le; Tung X
• Application Number:
  US11/682,124
• Publication Number:
  US 20080218101A1
• Time in Patent Office: 820 Days
• Field of Search: 315/291, 315/294, 315/297, 315/307, 315/314, 315/209.R, 315/274, 315/360, 323237-238, 323/242, 323/247, 323/300, 323/301, 323/321, 323/323, 323/326
• US Class Current: 315/307
• CPC Class Codes: H05B 39/02 Switching on, e.g. with predetermined rate of increase of lighting current

Abstract

A low voltage lighting system includes a transformer having at least a primary winding and a secondary winding. The low voltage lighting system also includes one or more lighting elements and a voltage control circuit. The lighting elements are coupled to the secondary winding. The voltage control circuit is electrically coupled with the primary winding. The voltage control circuit is configured to automatically increase the voltage applied to the primary winding of the transformer in a predetermined manner from a first voltage to a second voltage over a predetermined period of time.

Claims

1. A low voltage lighting system comprising:

(a) a transformer having at least a primary winding and a secondary winding;

(b) a lighting element electrically coupled with the secondary winding; and

(c) a voltage control circuit electrically coupled with the primary winding, the voltage control circuit being configured to automatically increase the voltage applied to the primary winding of the transformer in a predetermined manner from a first voltage to a second voltage over a predetermined period of time, the voltage control circuit including;

(i) a soft-start circuit that controls a rate of increase of voltage applied to the primary winding of the transformer from the first voltage to the second voltage, and

(ii) a bypass circuit that bypasses the soft start circuit and applies a third voltage to the primary winding.

2. The low voltage lighting system of claim 1, wherein the first voltage is one of equal to zero and greater than zero.

3. The low voltage lighting system of claim 1, wherein the voltage control circuit controls the length of time that the first voltage is applied to the primary winding.

4. A low voltage lighting system comprising:

(a) a transformer having at least a primary winding and a secondary winding;

(b) a lighting element electrically coupled with the secondary winding; and

(c) a voltage control circuit electrically coupled with the primary winding, the voltage control circuit being configured to automatically increase the voltage applied to the primary winding of the transformer in a predetermined manner from a first voltage to a second voltage over a predetermined period of time, the voltage control circuit including a soft-start circuit that controls a rate of increase of voltage applied to the primary winding of the transformer from the first voltage to the second voltage, the soft-start circuit including;

(i) a zero cross detector that detects the zero crossing of an alternating current (AC) voltage;

(ii) a voltage controlled phase timer electrically coupled to the output of the zero cross detector that detects the zero crossing of an AC voltage and generates output signals; and

(iii) a transformer switch electrically coupled with the output of the voltage controlled phase timer, the voltage controlled phase timer controlling the ON time of the transformer switch, the transformer switch applying a voltage to the primary winding of the transformer.

5. A low voltage lighting system comprising:

(a) a transformer having at least a primary winding and a secondary winding;

(b) a lighting element electrically coupled with the secondary winding; and

(c) a voltage control circuit electrically coupled with the primary winding, the voltage control circuit being configured to automatically increase the voltage applied to the primary winding of the transformer in a predetermined manner from a first voltage to a second voltage over a predetermined period of time, the voltage control circuit including a soft-start circuit that controls a rate of increase of voltage applied to the primary winding of the transformer from the first voltage to the second voltage, the voltage control circuit also including a bypass circuit that bypasses the soft start circuit and applies a third voltage to the primary winding, the bypass circuit including;

(i) a delay timer that has a second predetermined delay time; and

(ii) a bypass switch that is electrically coupled to the output of the delay timer, the bypass switch being configured to bypass the voltage control circuit and apply the third voltage to the primary winding, the delay timer actuating the bypass switch after the second predetermined delay time.

6. A low voltage lighting system comprising:

(a) a transformer having at least a primary winding and a secondary winding;

(b) a lighting element electrically coupled with the second winding; and

(c) a voltage control circuit electrically coupled with the primary winding, the voltage control circuit being configured to automatically increase the voltage applied to the primary winding of the transformer in a predetermined manner from a first voltage to a second voltage over a predetermined period of time, the voltage control circuit comprising;

(i) a zero cross detector that detects the zero crossing of an alternating current (AC) voltage;

(ii) a voltage controlled phase timer electrically coupled to the output of the zero cross detector, the voltage controlled circuit automatically increasing the voltage applied to the primary winding of the transformer from a first voltage to a second voltage over the predetermined period of time;

(iii) a transformer switch electrically coupled with the output of the voltage controlled phase timer and electrically coupled with the primary winding of the transformer, the voltage controlled phase timer controlling the ON time of the transformer switch to apply a voltage to the primary winding of the transformer;

(iv) a delay timer having a second predetermined delay time; and

(v) a bypass switch electrically coupled with the delay timer, the bypass switch being configured to bypass at least a portion of the voltage controlled circuit and apply a third voltage to the primary winding of the transformer, the delay timer actuating the bypass switch after the second predetermined delay time.

7. The low voltage lighting system of claim 6, wherein the voltage controlled phase timer includes a delay ramp timer establishing a first predetermined delay time that the first voltage is applied to the primary winding.

8. The low voltage lighting system of claim 6, further comprising:

(vi) a bypass switch driver electrically coupled to the delay timer and electrically coupled to the bypass switch, the delay timer controlling the bypass switch driver, the bypass switch driver controlling the bypass switch.

9. A method of controlling at least one low voltage lighting element, the lighting element being electrically coupled with a secondary winding of a transformer, the transformer having at least a primary winding and the secondary winding, the method comprising:

after a first delay time, increasing the voltage applied to the primary winding of the transformer from a first voltage to a second voltage in a predetermined manner over a predetermined period of time using an automatic voltage control circuit;

controlling a rate of increase of voltage applied to the primary winding of the transformer from the first voltage to the second voltage using a soft-start circuit; and

after a second delay time, applying a third voltage to the primary winding of the transformer.

10. The method of claim 9, wherein the third voltage is applied to the primary winding of the transformer by bypassing the automatic voltage control circuit.

11. The method of claim 9, further comprising:

applying the first voltage to the primary winding of the transformer for a first predetermined delay time.