Piezoelectric transducer drive circuit and cold cathode tube lighting device having the same

A cold cathode tube lighting device comprising a piezoelectric transducer drive circuit driving a piezoelectric transducer boosting an alternating voltage applied intermittently to a pair of primary electrodes and outputting the boosted alternating voltage from a secondary electrode, said piezoelectric transducer drive circuit comprising:

• a detection circuit detecting a signal indicating a state of a load connected to the secondary electrode and outputting one of a peak voltage and an average voltage thereof;
• an error amplification circuit comparing the output voltage of the detection circuit with an error reference voltage and outputting a voltage according to a difference therebetween;
• and
• a voltage-controlled oscillator controlled by the output voltage of the error amplification circuit and generating a clock determining a frequency of the alternating voltage applied to said primary electrodes,
• said error amplification circuit controlling the voltage-controlled oscillator such that, when a voltage-applying operation is stopped in an intermittent operation and thereafter the voltage-applying operation is started, said frequency of the alternating voltage is always gradually reduced from a high point and stabilized,
• wherein said cold cathode tube lighting device further comprises:
• the piezoelectric transducer driven by the piezoelectric transducer drive circuit to boost the alternating voltage applied intermittently to the pair of primary electrodes and outputting the boosted alternating voltage from the secondary electrode;
• a cold cathode tube connected as a load to the secondary electrode of the piezoelectric transducer;
• and
• an impedance device connected in series with the cold cathode tube to allow the detection circuit of the piezoelectric transducer drive circuit to detect the signal indicating the state of the load connected to the secondary electrode.