Self oscillation circuits

• US 20030151931A1
• Filed: 02/11/2003
• Published: 08/14/2003
• Est. Priority Date: 02/14/2002
• Status: Active Grant

• Current Assignee: Kazuo Kohno
• Original Assignee: Kazuo Kohno
• Inventors: Kohno, Kazuo
• Granted Patent: US 6,747,421 B2
• Time in Patent Office: Days
• US Class Current: 363/22
• CPC Class Codes: H02M 7/5381 Parallel type
• CPC Class Codes: H05B 41/2822 using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
• CPC Class Codes: H05B 41/2824 using control circuits for the switching element H05B41/2822 takes precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

An object of the present invention is to provide a small size output transformer capable of producing sine wave oscillation at stability and high efficiency. A drive circuit including a switching circuit is connected to DC power source input units 12a, 12b, and an output transformer 10 is connected to the drive circuit. At the drive circuit, the switching circuit is turned on and off on the basis of a feedback signal of the primary side resonance voltage induced in the input side primary winding of the output transformer. The energizing direction of the DC power source to the output transformer is converted in clockwise and counter-clockwise direction by the on and off of the switching circuit, and the power source is applied as the AC signal to the input side primary winding of the output transformer. The phase detecting means detects the phase of the resonance waveform at the primary side of the output transformer 10 and outputs the phase signal. The control circuit connected to the drive circuit converts the signal of the phase detecting means to two phase signals of mutually reversal phases and outputs the drive signal for the on-off control of the switching circuit of the drive circuit.

Claims

1. A self oscillation circuit for use as a converter to convert a DC power source to AC power source, which circuit comprises a DC power source input unit, an output transformer, an LC primary side resonance circuit formed at primary side of an input of the output transformer, and a switching circuit that turns on and off the DC voltage and being provided with a drive circuit that turns the switching circuit on and off on the basis of a feedback signal of the primary side resonance voltage induced in the LC primary side resonance circuit and converts the energizing direction of the DC power source to the output transformer in clockwise and counter-clockwise direction to drive the output transformer, a phase detecting means for detecting the phase signal of a resonance waveform at the primary side of the output transformer and outputting the phase signal, and a control circuit for outputting the phase signal as the drive signal that controls the on-off of the switching circuit.

2. The self oscillation circuit according to claim 1, wherein the LC primary side resonance circuit is formed by the series resonance circuit, and the resonance voltage is taken out from a mid point of the series resonance circuit to match the phase with the resonance electric current, and the control circuit is caused to operate the positive feedback.

3. The self oscillation circuit according to claim 1, wherein the load is connected to the secondary side of the output transformer, and means is provided to detect the electric current flowing in the load, and a start compensating circuit is provided for supplying a start signal for self oscillation to the control circuit before the electric current flows to the load at the time of conversion of the power source to the on on the basis of the signal from the electric current detecting means.

4. The self oscillation circuit according to claim 1, wherein the output transformer is one input two output type winding type transformer and a primary winding is wound on the center of a bobbin, and a secondary winding is disposed at both sides of the primary winding.

5. The self oscillation circuit according to claim 1, wherein the output transformer is made as a piezoelectric transformer, and the piezoelectric transformer is made as a capacitor, and an LC primary side resonance circuit is formed by the capacitor and an inductor connected to the switching circuit.

6. The self oscillation circuit according to claim 1, wherein the inductor is connected instead of the output transformer, and a series resonance circuit is formed by the inductor and the capacitor connected to the switching circuit, and being formed between the switching circuit and the earth in lieu of the primary side resonance circuit, and the load is connected to the inductor connected to the earth side or the capacitor in parallel manner.