Abstract: A switching power supply circuit includes a switching element that switches power fed to a primary winding of a transformer and thus induces a voltage in the secondary winding, and an oscillation circuit that oscillates to generate a pulse signal to control switching action. The oscillation circuit repeatedly performs intermittent oscillation of the pulse signal, and in each of the intermittent oscillation cycles, increases or decreases the number of pulses in the pulse signal to lengthen or shorten the oscillating portion of the pulse signal, and at the time of lengthening or shortening, the oscillation circuit respectively lengthens or shortens an oscillation-halted portion, thus varying the period of the intermittent oscillation cycles.

Abstract: This power supply device includes a substrate, a transformer mounted on a first surface of the substrate, and a switch element electrically connected to the transformer, mounted on a second surface of the substrate, while the switch element is arranged in a position different from a position on the second surface corresponding to a position on the first surface in which the transformer is mounted.

Abstract: A self-excited inverter comprises a pair of switching devices and a transformer having a primary side to which the switching devices are connected and a secondary side to which a lamp is connected. A pulse voltage is applied alternately to gates of the individual switching devices through a drive winding of the transformer, causing the switching devices to turn on and off in alternate turns to produce an AC voltage which is supplied from a pair of main windings of the transformer to the secondary side thereof. An input voltage supplied to the main windings of the transformer is divided by a voltage divider circuit configured with a plurality of resistors and voltages divided by the voltage divider circuit are applied to the gates of the individual switching devices so that the startup voltage follows the input voltage.

Abstract: A synchronous rectifier circuit (DC-DC converter) includes a CR integration circuit and a discharge circuit. The CR integration circuit outputs a voltage that varies at delayed timing as compared with a voltage induced in a secondary-side main winding. The discharge circuit discharges a gate voltage of a rectifier transistor as a result of conduction of a discharge transistor in response to the output voltage from the CR integration circuit. According to such a configuration, the rectifier transistor is turned off earlier than the timing of switching of polarity of voltages induced in the secondary-side main winding and a secondary-side auxiliary winding in response to turn-on of a primary-side transistor.

Abstract: A fluorescent tube power supply including an inverter power supply which outputs a DC voltage, and an inverter which converts an output of the inverter power supply to an AC; wherein a power stabilizing unit for stabilizing a power input to the inverter is arranged between the inverter power supply and the inverter; and a feedback control of the inverter power supply is performed based on an output of the power stabilizing unit. The power stabilizing unit detects a current flowing between the inverter power supply and the inverter, and the feedback control of the inverter power supply is performed based on the current.

Abstract: A push-pull inverter allows a power supply unit to supply an input voltage to two primary windings of a transformer, and allows MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) to drive the transformer in push-pull mode so as to increase the input voltage supplied from the power supply unit and to output the increased voltage as an output voltage from a secondary winding of the transformer. The two primary windings of the transformer are mixedly wound on a same bobbin without being separated, so that when the transformer is driven, the two primary windings of the transformer are prevented from resonating with each other. This makes it possible to prevent turbulence in the input current, thereby reducing loss (power loss) of the MOSFETs, allowing the transformer to have a high efficiency.

Abstract: A synchronous rectifier circuit (DC-DC converter) includes a CR integration circuit and a discharge circuit. The CR integration circuit outputs a voltage that varies at delayed timing as compared with a voltage induced in a secondary-side main winding. The discharge circuit discharges a gate voltage of a rectifier transistor as a result of conduction of a discharge transistor in response to the output voltage from the CR integration circuit. According to such a configuration, the rectifier transistor is turned off earlier than the timing of switching of polarity of voltages induced in the secondary-side main winding and a secondary-side auxiliary winding in response to turn-on of a primary-side transistor.

Abstract: A self-excited inverter comprises a pair of switching devices and a transformer having a primary side to which the switching devices are connected and a secondary side to which a lamp is connected. A pulse voltage is applied alternately to gates of the individual switching devices through a drive winding of the transformer, causing the switching devices to turn on and off in alternate turns to produce an AC voltage which is supplied from a pair of main windings of the transformer to the secondary side thereof. An input voltage supplied to the main windings of the transformer is divided by a voltage divider circuit configured with a plurality of resistors and voltages divided by the voltage divider circuit are applied to the gates of the individual switching devices so that the startup voltage follows the input voltage.

Abstract: A fluorescent tube power supply including an inverter power supply which outputs a DC voltage, and an inverter which converts an output of the inverter power supply to an AC; wherein a power stabilizing unit for stabilizing a power input to the inverter is arranged between the inverter power supply and the inverter; and a feedback control of the inverter power supply is performed based on an output of the power stabilizing unit. The power stabilizing unit detects a current flowing between the inverter power supply and the inverter, and the feedback control of the inverter power supply is performed based on the current.