LIGHTING DEVICE AND LUMINAIRE USING THE SAME

PROBLEM TO BE SOLVED: To provide a lighting device which can light up a light-emitting element to a deep light control level and can smoothly change the brightness of the light-emitting element over a wide range, and a luminaire using the same.SOLUTION: A lighting device 1 comprises a first current adjustment part 123 for adjusting the current flowing in an LED 31 by turning on/off a transistor Q2 according to a PWM signal S3 in which the on-duty ratio changes in response to the light control signal S1 from outside; and a second current adjustment part 122 for adjusting the current flowing in the LED 31 by changing the voltage applied to a gate of the transistor Q2 according to the light control signal S1. When the light control level by the light control signal S1 is a predetermined value or more, the first current adjustment part 123 controls the brightness of the LED 31, and when the light control level is less than the predetermined value, a control state controlled by the first current adjustment part 123 when the light control level is the predetermined value, is kept and the brightness of the LED 31 is controlled by the second current adjustment part 122. 【課題】より深い調光レベルまで発光素子を点灯可能で且つ発光素子の明るさを広範囲に亘って滑らかに変化可能な点灯装置及びそれを用いた照明器具を提供する。【解決手段】点灯装置１は、外部からの調光信号Ｓ１に応じてオンデューティ比が変化するＰＷＭ信号Ｓ３に従ってトランジスタＱ２をオン／オフさせることでＬＥＤ３１に流れる電流を調整する第１電流調整部１２３と、調光信号Ｓ１に従ってトランジスタＱ２のゲートに印加する電圧を変化させることでＬＥＤ３１に流れる電流を調整する第２電流調整部１２２とを備える。調光信号Ｓ１による調光レベルが所定値以上である場合には、第１電流調整部１２３によりＬＥＤ３１の明るさを制御し、調光レベルが所定値より小さい場合には、調光レベルが所定値である場合における第１電流調整部１２３の制御状態を保ちつつ、第２電流調整部１２２によりＬＥＤ３１の明るさを制御する。【選択図】図１