Lamp current control circuit

• US 6,958,582 B2
• Filed: 03/15/2004
• Issued: 10/25/2005
• Est. Priority Date: 03/15/2004
• Status: Expired due to Fees

• Current Assignee: Zippy Technology Corporation
• Original Assignee: Zippy Technology Corporation
• Inventors: Wu, Kuang-Ming, Chou, Chin-Wen, Cheng, Eddie
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Ho, Binh Van
• Application Number:
  US10/799,726
• Publication Number:
  US 20050200307A1
• Time in Patent Office: 589 Days
• Field of Search: H05/B03.7/02, 315/291, 315/245, 315/209.R, 315/307, 315/209, 363/98, 363/16
• US Class Current: 315/291
• CPC Class Codes: H05B 41/2828 using control circuits for the switching elements H05B41/2827 takes precedence
• CPC Class Codes: H05B 41/2858 for protecting the lamp against abnormal operating conditions

Abstract

The present invention is a lamp current control circuit applied to a high voltage outputting combination for providing uniformity of lamp current of at least one load. Voltage dividing units of the lamp current control circuit receive high power signals output by the high voltage outputting combination and redistributes high power signals to lower power signals. A signal-processing unit receives the lower power signals distributed by the voltage-dividing units, compares the lower power signals with each other, and outputs the compensation power signal to the control unit. The compensation power signal is compared with a reference power signal of a variable unit, and a comparison power signal is output, thereby uniformly distributing the lamp current inside the load. For the above reason, it prevents power loss inside the load or damage to the load from abnormal lamp currents.

Claims

1. A lamp current control circuit applied in a high voltage outputting combination for providing uniformity of lamp current of at least one load, the high voltage outputting combination including a control unit providing voltage distribution signals, driving units to receive the voltage distributing signals to convert a voltage into high voltage outputting ends, voltage step-up units, and the load connected to the high voltage outputting ends, the lamp current control circuit characterized in that:

the lamp current control circuit is disposed between the high voltage outputting ends of the voltage step-up unit and the control unit for redistributing high power signals as low power signals, processing the low power signals, outputting a compensation power signal to the control unit, and then processing the redistribution of voltage.

2. The lamp current control circuit according to claim 1, comprising:

at least two voltage dividing units being a voltage dividing circuit consisting of a plurality of impedance elements disposed at the high voltage outputs of the voltage step-up units; and

a signal processing unit receiving the lower power signals distributed by the voltage dividing units, comparing the lower power signals with each other, and then outputting the compensation power signal to the control unit.

3. The lamp current control circuit according to claim 2, wherein the signal-processing unit is compared with a variable unit provided with a reference power signal in advance.

4. The lamp current control circuit according to claim 3, wherein the signal-processing unit is a voltage differential amplifier.

5. The lamp current control circuit according to claim 3, wherein the signal-processing unit is a full-wave rectifier.

6. The lamp current control circuit according to claim 3, wherein the variable unit is a variable resistor.

7. The lamp current control circuit according to claim 2, wherein the control unit including an error amplifier receives and compares the compensation reference power signals and, outputting a comparison power signal;

a phase driving circuit receiving the comparison power signal; and

a voltage control oscillator outputting a resonant frequency.

8. The lamp current control circuit according to claim 1, wherein the load is a lamp with a long dimension.

9. The lamp current control circuit according to claim 1, wherein the loads are two lamps with a short dimension.