Cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer
First Claim
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1. A cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer, comprising:
- an oscillation circuit which generates an alternating-current driving signal;
a driving circuit which amplifies said alternating-current driving signal;
a piezoelectric transformer in which an input electrode and an output electrode are disposed on a piezoelectric element; and
a cold cathode fluorescent lamp, whereina resistor having a value sufficient to suppress fluctuation of said alternating-current driving signal is connected in series between an output of said amplifying circuit and said input electrode of said piezoelectric transformer.
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Abstract
An AC driving signal of a frequency in the vicinity of the resonance frequency of a piezoelectric transformer is generated by a variable oscillation circuit and the waveform of the output signal of the variable oscillation circuit is shaped so as to be substantially sinusoidal by a waveform shaping circuit and the output of the waveform shaping circuit is subjected by a driving circuit to current amplification or voltage amplification so as to be amplified to a level sufficient for driving the piezoelectric transformer and the output of the driving circuit is subjected to current limitation, and then input to the piezoelectric transformer and the output signal of the transformer is applied to a cold cathode fluorescent lamp so that the cold cathode fluorescent lamp is lit and even if the impedance of the cold cathode fluorescent lamp decreases, the piezoelectric transformer cannot supply a large current.
13 Citations
20 Claims
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1. A cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer, comprising:
- an oscillation circuit which generates an alternating-current driving signal;
a driving circuit which amplifies said alternating-current driving signal;
a piezoelectric transformer in which an input electrode and an output electrode are disposed on a piezoelectric element; and
a cold cathode fluorescent lamp, whereina resistor having a value sufficient to suppress fluctuation of said alternating-current driving signal is connected in series between an output of said amplifying circuit and said input electrode of said piezoelectric transformer. - View Dependent Claims (2, 9, 10, 11)
- an oscillation circuit which generates an alternating-current driving signal;
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3. A cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer, comprising:
- an oscillation circuit which generates an alternating-current driving signal;
a driving circuit which amplifies said alternating-current driving signal;
a piezoelectric transformer which an input electrode and an output electrode are disposed on a piezoelectric element; and
a cold cathode fluorescent lamp, whereinsaid driving circuit comprises a current amplifying circuit and a step-up transformer, and a resistor or an inductance is connected in series between an output terminal of said step-up transformer and the input electrode, said resistor or said inductance having an impedance of about 5% to 20% of an input impedance of said piezoelectric transformer to suppress fluctuation of said alternating-current driving signal said capacitor having a capacitance value that is balanced to an output capacitance value of said piezoelectric transformer. - View Dependent Claims (12)
- an oscillation circuit which generates an alternating-current driving signal;
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4. A cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer, comprising:
- an oscillation circuit which generates an alternating-current driving signal;
a driving circuit which amplifies said alternating-current driving signal;
a piezoelectric transformer in which an two input electrode and an two output electrode are disposed on a piezoelectric element; and
a cold cathode fluorescent lamp, whereina capacitor is connected in series to a ground side of said cold cathode fluorescent lamp, said capacitor having a capacitance value that is balanced to an output capacitance value of said piezoelectric transformer. - View Dependent Claims (5, 13, 14)
- an oscillation circuit which generates an alternating-current driving signal;
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6. A cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer, comprising:
- an oscillation circuit which generates an alternating-current driving signal;
a driving circuit which amplifies said alternating-current driving signal;
a piezoelectric transformer in which two input electrodes and two output electrodes are disposed on a rectangular plate of a piezoelectric element; and
a cold cathode fluorescent lamp, wherein(a) said input electrodes are polarized in a thickness direction of said rectangular plate and said output electrodes are polarized in a longitudinal direction of said rectangular plate; and (b) said output electrodes are connected to said cold cathode fluorescent lamp providing balanced outputs. - View Dependent Claims (7, 8, 15)
- an oscillation circuit which generates an alternating-current driving signal;
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16. A cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer, comprising:
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an oscillation circuit which generates an alternating-current driving signal; a driving circuit which amplifies said alternating-current driving signal; a piezoelectric transformer in which an input electrode and an output electrode are disposed on a piezoelectric element; a cold cathode fluorescent lamp, and a pulsation suppression means for suppressing pulsation in the driving signal free of feedback.
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17. A cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer, comprising
an oscillation circuit which generates an alternating-current driving signal; -
a driving circuit which amplifies said alternating-current driving signal; a piezoelectric transformer in which an input electrode, an output electrode and a grounded electrode are disposed on a piezoelectric element;
said input electrode coupled to said driving circuit for receiving said alternating-current driving signal;a cold cathode fluorescent lamp connected in series between said output electrode and said grounded electrode; and means for pulsation suppression free of feedback placed between said driving circuit and said grounded electrode. - View Dependent Claims (20)
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18. A cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer, comprising
an oscillation circuit which generates an alternating-current driving signal; -
a driving circuit which amplifies said alternating-current driving signal; a piezoelectric transformer in which an input electrode, an output electrode and a grounded electrode are disposed on a piezoelectric element;
said input electrode coupled to said driving circuit for receiving said alternating-current driving signal;a cold cathode fluorescent lamp connected in series between said output electrode and said grounded electrode; and means for pulsation suppression being a resistor placed in series between said driving circuit and said input electrode.
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19. A cold cathode fluorescent lamp driving apparatus using a piezoelectric transformer, comprising
an oscillation circuit which generates an alternating-current driving signal; -
a driving circuit which amplifies said alternating-current driving signal; a piezoelectric transformer in which an input electrode, an output electrode and a grounded electrode are disposed on a piezoelectric element;
said input electrode coupled to said driving circuit for receiving said alternating-current driving signal;a cold cathode fluorescent lamp connected in series between said output electrode and said grounded electrode; and means for pulsation suppression being a resistor placed in series between said output electrode and said fluorescent lamp.
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Specification
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Current AssigneePanasonic Photo & Lighting Co. Ltd. (Panasonic Holdings Corporation)
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Original AssigneeMatsushita Electric Industrial Company Limited (Panasonic Holdings Corporation), West Electric Company Limited
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InventorsIwata, Hiroshi, Makino, Hiroshi, Hasegawa, Wataru, Murata, Kazuou, Kawasaki, Osamu
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Primary Examiner(s)Shingleton, Michael B
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Application NumberUS08/698,049Time in Patent Office1,286 DaysField of Search315/224, 315/307, 315/DIG. 5, 315/DIG. 7, 315/276, 363/133US Class Current315/224CPC Class CodesH05B 41/2822 using specially adapted com...Y10S 315/05 Starting and operating circ...Y10S 315/07 Starting and control circui...
