Abstract: A signal processing circuit includes an I/V conversion circuit (current/voltage conversion section) that converts an oscillation current of a vibrator into a voltage, an RC filter (phase shift section) that shifts a phase of the output signal of the I/V conversion circuit, a full-wave rectifier (part of a drive amplitude control section) that binarizes a signal that has been shifted in phase to generate a switch control signal, a comparator (reference signal generation section) that generates a reference signal for synchronous detection based on the output signal of the I/V conversion circuit, and an EXOR circuit (clock signal generation section) that generates a clock signal for a switched capacitor filter (SCF) that has a frequency twice a frequency of a drive signal based on a phase difference between the reference signal and the switch control signal.

Abstract: A detection circuit includes a synchronous detection circuit (synchronous detection section) that synchronously detects a signal that includes a detection signal of a vibrator (an output signal of an amplifier), a switched capacitor filter (SCF) circuit that filters a signal that has been synchronously detected by the synchronous detection circuit (an output signal of a programmable gain amplifier), and an output buffer that buffers and outputs a signal that has been filtered by the SCF circuit, the gain of the SCF circuit being larger than 1.

Abstract: A driver circuit includes a comparator (drive signal generation section) that generates a drive signal based on a signal obtained by converting an oscillation current of a vibrator that has been input via a first signal line into a voltage using an I/V conversion circuit (current/voltage conversion section), and supplies the drive signal to the vibrator via a second signal line, an oscillation detection circuit (oscillation detection section) that detects whether or not the oscillation current has reached a predetermined value after the vibrator has started to oscillate, a startup oscillation circuit (startup oscillation section) that assists an oscillation operation of the vibrator until the oscillation current reaches the predetermined value, and a switch that separates a capacitor from the second signal line until the oscillation current reaches the predetermined value, and connects the capacitor to the second signal line when the oscillation current has reached the predetermined value.

Abstract: A detection circuit includes a synchronous detection circuit (synchronous detection section) that synchronously detects a signal that includes a detection signal of a vibrator (an output signal of an amplifier), a switched capacitor filter (SCF) circuit that filters a signal that has been synchronously detected by the synchronous detection circuit (an output signal of a programmable gain amplifier), and an output buffer that buffers and outputs a signal that has been filtered by the SCF circuit, the gain of the SCF circuit being larger than 1.

Abstract: A driver circuit includes a comparator (drive signal generation section) that generates a drive signal based on a signal obtained by converting an oscillation current of a vibrator that has been input via a first signal line into a voltage using an I/V conversion circuit (current/voltage conversion section), and supplies the drive signal to the vibrator via a second signal line, an oscillation detection circuit (oscillation detection section) that detects whether or not the oscillation current has reached a predetermined value after the vibrator has started to oscillate, a startup oscillation circuit (startup oscillation section) that assists an oscillation operation of the vibrator until the oscillation current reaches the predetermined value, and a switch that separates a capacitor from the second signal line until the oscillation current reaches the predetermined value, and connects the capacitor to the second signal line when the oscillation current has reached the predetermined value.

Abstract: A signal processing circuit includes an I/V conversion circuit (current/voltage conversion section) that converts an oscillation current of a vibrator into a voltage, an RC filter (phase shift section) that shifts a phase of the output signal of the I/V conversion circuit, a full-wave rectifier (part of a drive amplitude control section) that binarizes a signal that has been shifted in phase to generate a switch control signal, a comparator (reference signal generation section) that generates a reference signal for synchronous detection based on the output signal of the I/V conversion circuit, and an EXOR circuit (clock signal generation section) that generates a clock signal for a switched capacitor filter (SCF) that has a frequency twice a frequency of a drive signal based on a phase difference between the reference signal and the switch control signal.

Abstract: An electronic ballast for a discharge lamp has a compact arrangement of electric parts. The ballast includes an AC-DC converter and an inverter giving a high frequency output voltage for operating the lamp. The inverter includes switching elements, a control circuit, and an output transformer for connection with the lamp. A single circuit board mounts the electric parts forming the converter and the inverter. The circuit board is accommodated within a tubular casing together with a dielectric sheet which is provided for insulating the circuit board as well as the electric parts from the casing. The output transformer is mounted on a top surface of the circuit board together with some of the other electric parts. The ballast includes chip components forming a detection circuit for lamp condition, and the circuit board mounts the chip components on a bottom surface at a location immediately opposite of the output transformer.

Abstract: An electronic ballast for a discharge lamp has a compact arrangement of electric parts. The ballast includes an AC-DC converter and an inverter giving a high frequency output voltage for operating the lamp. The inverter includes switching elements, a control circuit, and an output transformer for connection with the lamp. A single circuit board mounts the electric parts forming the converter and the inverter. The circuit board is accommodated within a tubular casing together with a dielectric sheet which is provided for insulating the circuit board as well as the electric parts from the casing. The output transformer is mounted on a top surface of the circuit board together with some of the other electric parts. The ballast includes chip components forming a detection circuit for lamp condition, and the circuit board mounts the chip components on a bottom surface at a location immediately opposite of the output transformer.