Panasonic Corporation

Kazuhiko Itou

Masayoshi Gyoten

Etsuji Morimoto

Shiro Iida

Akira Takahashi

Shougo Takahashi

A lamp includes an arc tube and a lighting unit for lighting the arc tube. The lighting unit includes a rectifier circuit, a smoothing circuit for partial smoothing, and an inverter circuit having a pair of switching elements. The smoothing circuit smoothes portions of the output voltage of the rectifier circuit below the first voltage value and outputs a voltage that falls between the first voltage value and the second voltage value. The discharge sustaining voltage of the arc tube is set to fall between the first and second values of the voltage Vdc output from the smoothing circuit.

Visible indication of mistaken lamp use

Provided is a lighting unit and a discharge lamp each of which is capable of causing a capacitor to break down by heat generated in a heat generating component, so that circuit operation is safely terminated without any additional cost. A compact self-ballasted fluorescent lamp is provided with a lighting unit () housed in a case. The lighting unit () causes an arc tube to emit light and is composed of a plurality of electronic components, including a rectifier/smoothing circuit portion, an inverter circuit portion having transistors (Qand Q), a resonant circuit portion, and a preheating circuit portion having a positive temperature coefficient element. Among the plurality of electronic components, the transistors (Qand Q) and the positive temperature coefficient element generate excessive heat when, for example, the lamp is operated at the end of electrode's life. Capacitors (Cand C) disposed in the vicinity of the positive temperature coefficient element would break down by heat in a short mode.

Lighting unit and discharge lamp

Discoloration and deformation of a resin case triggered by heat generation from a failed circuit component at the end of the life of an arc tube are prevented without increasing the cost and size. A lighting unit that lights a light source with an inverter while receiving electric power from an AC power supply, and that contains a lighting circuit that includes a plurality of circuit components inclusive of capacitors. Among the capacitors, all capacitors with an applied voltage of 50V or greater (C, C, C, C, C, CDand CD) are foil type film capacitors with exceptions of smoothing electrolytic capacitors (CDand CD).

Growing community of inventors

Osaka, Japan

Kazuhiko Itou