JPH0982479A - Fluorescent lamp driving circuit and piezoelectric ceramic transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent lamp driving circuit of simple configuration by furnishing a piezoelectric ceramic transformer with an output electrode to drive a fluorescent lamp and a feedback electrode for feedback signal output to actuate self-exciting oscillation. SOLUTION: From a power supply terminal 1 a voltage is impressed, which is turned into a high voltage by a piezoelectric ceramic transformer 4 and supplied to a fluorescent lamp 2 from an electrode for output 4c. From the feedback electrode 4d of the transformer 4, a feedback signal of low voltage is supplied to the base of an NPN transistor 3 to actuate self-exciting oscillation. Because the feedback signal from the feedback electrode 4d of the transformer 4 has a low voltage, there is no need to provide any high voltage capacitor. Because the phase of the feedback signal from the feedback electrode 4c of the transformer 4 becomes the phase of the voltage necessary for oscillation of high voltage, the fluorescent lamp driving cirucuit to be achieved may have a simple circuitry configuration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp driving circuit suitable for driving a fluorescent lamp used as a backlight of a liquid crystal display, and a piezoelectric ceramic transformer used in the fluorescent lamp driving circuit.

[0002]

2. Description of the Related Art Some fluorescent lamp driving circuits used for driving fluorescent lamps used as backlights of liquid crystal displays use a piezoelectric ceramic transformer to obtain a high voltage.

As shown in FIG. 6, this piezoelectric ceramic transformer has a rectangular plate-shaped piezoelectric ceramic 101 and an input electrode 10 formed on the upper and lower main surfaces of the piezoelectric ceramic 101.
2, 103 and the output electrode 1 formed on the end surface of the piezoelectric ceramic 101 on the side far from the input electrodes 102, 103.
04. Here, normally, the input electrode 10
2, 103 are formed from one end of the piezoelectric ceramic 101 to approximately half the position in the longitudinal direction.
Is formed on almost the entire end surface of the piezoelectric ceramic 101. One of the input electrodes 102 is connected to the power supply terminal 1
05, the other input electrode 103 is connected to the ground side terminal 106, and the output electrode 104 is connected to the output terminal 107.
Connected to.

When driving the piezoelectric ceramic transformer, a voltage is supplied from the input electrode 105, whereby the piezoelectric ceramic 101 resonates, and as a result, a voltage converted into a high voltage is output from the output terminal 107. To be done.

An example of a fluorescent lamp drive circuit using such a piezoelectric ceramic transformer is shown in FIG. This fluorescent lamp drive circuit is of a self-excited oscillation type, and includes an NPN transistor 111, a piezoelectric ceramic transformer 112 having a first input electrode 112a, a second input electrode 112b and an output electrode 112c, and a phase shift. Circuit 113 and converts the voltage supplied from the power supply terminal 114 into a high voltage and supplies the high voltage to the fluorescent lamp 115.

The power supply terminal 114 is connected to the coil 1
It is connected to the first input electrode 112 a of the piezoelectric ceramic transformer 112 via 16 and to the base of the NPN transistor 111 via a resistor 117. The collector of the NPN transistor 111 is
The first input electrode 11 of the piezoelectric ceramic transformer 112
The emitter of the NPN transistor 111 is connected to the second input electrode 112b of the piezoelectric ceramic transformer 112 and the ground side electrode 115b of the fluorescent lamp 115.
It is also connected to the ground-side terminal 118. On the other hand, the output electrode 112c of the piezoelectric ceramic transformer 112 supplies the fluorescent lamp 115 with a driving voltage so as to supply a driving voltage to the fluorescent lamp 115.
Of the NPN transistor 111 via the high voltage capacitor 119 and the phase shift circuit 113 so as to form a feedback circuit for performing self-oscillation. Here, the high breakdown voltage capacitor 119 arranged in the feedback circuit is for handling the high voltage output from the output electrode 112c of the piezoelectric ceramic transformer 112. Further, the phase shift circuit 113 arranged in the feedback circuit includes the piezoelectric ceramic transformer 11
Of the feedback signal from the output electrode 112c of the piezoelectric ceramic transformer 112 so that the phase of the voltage of the feedback signal from the second output electrode 112c becomes the phase of the voltage required for high-voltage oscillation by the piezoelectric ceramic transformer 112. This is for shifting the phase of the voltage.

[0007]

In such a conventional self-excited oscillation type fluorescent lamp drive circuit, as described above, the high voltage signal output from the output electrode 112c of the piezoelectric ceramic transformer 112 is used as a feedback signal. Therefore, it is necessary to dispose the high withstand voltage capacitor 119 in the feedback circuit. However, since the high withstand voltage capacitor 119 is relatively expensive, it is difficult to reduce the cost of the conventional self-oscillation type fluorescent lamp drive circuit.

Further, in the conventional self-oscillation type fluorescent lamp driving circuit, as described above, the piezoelectric ceramic transformer 11 is used.
Since the phase shift circuit 113 for shifting the phase of the voltage of the feedback signal from the second output electrode 112c is necessary, the circuit is complicated. Therefore, it is difficult to reduce the cost and the size of the conventional self-oscillation type fluorescent lamp drive circuit.

As a fluorescent lamp driving circuit using a piezoelectric ceramic transformer, there is a self-excited oscillation type circuit as described above, and also a self-excited oscillation type circuit as shown in FIG. The separately excited oscillation type fluorescent lamp drive circuit is a fluorescent lamp drive circuit provided with an independent oscillation circuit 120, and a signal required for high-voltage oscillation by the piezoelectric ceramic transformer 112 is oscillated from this oscillation circuit 120. . However, such a separately excited oscillation type fluorescent lamp driving circuit is not suitable for a fluorescent lamp driving circuit that requires cost reduction and downsizing because the circuit is complicated because an independent oscillation circuit 120 is required.

Therefore, the present invention has been proposed in view of such a conventional situation, and it is not necessary to dispose a high breakdown voltage capacitor or a phase shift circuit in the feedback circuit, and the circuit configuration is simple and downsized. It is an object of the present invention to provide a self-oscillation type fluorescent lamp drive circuit suitable for cost reduction. Another object of the present invention is to provide a piezoelectric ceramic transformer suitable for such a fluorescent lamp driving circuit.

[0011]

The fluorescent lamp drive circuit according to the present invention completed to achieve the above object uses a piezoelectric ceramic transformer in which electrodes are attached to a substantially rectangular plate-shaped piezoelectric ceramic. A self-oscillation type fluorescent lamp driving circuit, wherein the piezoelectric ceramic transformer has an output electrode for supplying a driving voltage to the fluorescent lamp and a feedback electrode for outputting a self-oscillation feedback signal. It is characterized by including.

Here, the piezoelectric ceramic transformer is
For example, the return electrode attached to the piezoelectric ceramic is formed to be smaller than the output electrode attached to the piezoelectric ceramic. At this time, it is preferable that the polarization direction of the piezoelectric ceramic near the output electrode be different from the polarization direction of the piezoelectric ceramic near the feedback electrode.

Alternatively, the piezoelectric ceramic transformer includes, for example, a pair of input electrodes formed so as to face the upper and lower main surfaces of the piezoelectric ceramic, and the distance from the input electrode to the return electrode is the input electrode. May be shorter than the distance from to the output electrode. Again,
The polarization direction of the piezoelectric ceramic near the output electrode,
The polarization direction of the piezoelectric ceramic in the vicinity of the return electrode is preferably different.

In such a fluorescent lamp driving circuit, the piezoelectric ceramic transformer has a feedback electrode for outputting a feedback signal for self-oscillation, in addition to an output electrode for supplying a driving voltage to the fluorescent lamp. Since the piezoelectric ceramic transformer is provided, the magnitude of the voltage of the feedback signal can be controlled. That is, for example, the return electrode of the piezoelectric ceramic transformer is made smaller than the output electrode, or the distance from the input electrode of the piezoelectric ceramic transformer to the return electrode is smaller than the distance from the input electrode to the output electrode. By making it short, the voltage of the feedback signal for self-excited oscillation output from the feedback electrode can be made significantly smaller than the drive voltage supplied from the output electrode to the fluorescent lamp.

Further, in such a fluorescent lamp driving circuit,
The polarization direction of the piezoelectric ceramic near the output electrode,
By controlling the polarization direction of the piezoelectric ceramic in the vicinity of the feedback electrode, the phase of the feedback signal for self-excited oscillation output from the feedback electrode is set to the phase of the voltage necessary for high-voltage oscillation by the piezoelectric ceramic transformer. can do. Therefore, in this fluorescent lamp drive circuit, the phase of the feedback signal from the piezoelectric ceramic transformer is controlled by appropriately controlling the polarization direction of the piezoelectric ceramic near the output electrode and the polarization direction of the piezoelectric ceramic near the feedback electrode. A phase shift circuit for shifting is unnecessary.

On the other hand, the piezoelectric ceramic transformer according to the present invention includes a substantially rectangular plate-shaped piezoelectric ceramic, a pair of input electrodes formed on the upper and lower main surfaces of the piezoelectric ceramic so as to face each other, and the input electrode. It is characterized in that it is provided with an output electrode and a feedback electrode formed on the end face of the piezoelectric ceramic on the far side, and a high voltage is output from the output electrode and a feedback signal is output from the feedback electrode. Here, it is preferable that the wirings from the pair of input electrodes, the output electrodes, and the feedback electrodes are drawn from the nodes of the primary vibration mode of the piezoelectric ceramic.

In such a piezoelectric ceramic transformer,
Since the feedback electrode for outputting the feedback signal is provided separately from the output electrode, the magnitude of the feedback signal voltage can be controlled separately from the magnitude of the voltage output from the output electrode. . That is, for example, the return electrode of the piezoelectric ceramic transformer is made smaller than the output electrode, or the distance from the input electrode of the piezoelectric ceramic transformer to the return electrode is smaller than the distance from the input electrode to the output electrode. By making it short, the voltage of the feedback signal for self-excited oscillation output from the feedback electrode can be made significantly smaller than the voltage output from the output electrode.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the following examples, and it goes without saying that the configuration can be arbitrarily changed without departing from the gist of the present invention.

First, an example of an embodiment of a fluorescent lamp drive circuit to which the present invention is applied will be described with reference to the circuit diagram shown in FIG.

This fluorescent lamp driving circuit converts the voltage supplied from the power supply terminal 1 into a high voltage by the self-excited oscillation system and supplies the high voltage to the fluorescent lamp 2, and the NPN transistor 3 and the first circuit. Input electrode 4a, second input electrode 4
b, an output electrode 4c, a return electrode 4d, and a piezoelectric ceramic transformer 4 having a piezoelectric ceramic 4e.

Here, the power supply terminal 1 is connected to the first input electrode 4a of the piezoelectric ceramic transformer 4 via the coil 5.
Is also connected to the base of the NPN transistor 3 via the resistor 6. The collector of the NPN transistor 3 is connected to the first input electrode 4a of the piezoelectric ceramic transformer 4, and the emitter of the NPN transistor 3 is the second electrode of the piezoelectric ceramic transformer 4.
Is connected to the ground side terminal 7 together with the input electrode 4b and the ground side electrode 2b of the fluorescent lamp 2. On the other hand, the output electrode 4c of the piezoelectric ceramic transformer 4 is connected to the input electrode 2a of the fluorescent lamp 2 so as to supply a driving voltage to the fluorescent lamp 2, and the return electrode 4d of the piezoelectric ceramic transformer 4 is connected.
Is a feedback circuit for self-excited oscillation.
It is connected to the base of the NPN transistor 3.

In the piezoelectric ceramic transformer 4, the voltage of the feedback signal for self-oscillation output from the feedback electrode 4d is significantly smaller than the voltage supplied from the output electrode 4c to the fluorescent lamp 2. Thus, the output electrode 4c and the feedback electrode 4d are provided. Further, the piezoelectric ceramic transformer 4 is arranged such that the phase of the voltage of the feedback signal from the feedback electrode 4d of the piezoelectric ceramic transformer 4 becomes the phase of the voltage required for high voltage oscillation by the piezoelectric ceramic transformer 4. The polarization state of 4e is controlled.

When the fluorescent lamp driving circuit as described above is used to emit light, a voltage is applied from the power supply terminal 1, and the applied voltage is converted into a high voltage by the piezoelectric ceramic transformer 4. And is supplied from the output electrode 4c to the fluorescent lamp 2. At this time, a low-voltage feedback signal NP is output from the feedback electrode 4d of the piezoelectric ceramic transformer 4.
It is supplied to the base of the N-transistor 3, which causes self-sustained pulsation.

In such a fluorescent lamp driving circuit, since the feedback signal from the feedback electrode 4d of the piezoelectric ceramic transformer 4 has a low voltage, it is not necessary to dispose a high withstand voltage capacitor in the feedback circuit portion. Further, in this fluorescent lamp drive circuit, the voltage phase of the feedback signal from the feedback electrode 4c of the piezoelectric ceramic transformer 4 is the phase of the voltage required for high-voltage oscillation by the piezoelectric ceramic transformer 4, so feedback is performed. It is not necessary to provide a phase shift circuit for shifting the phase of the feedback signal from the piezoelectric ceramic transformer 4 in the circuit portion. As described above, this fluorescent lamp drive circuit does not require an expensive high-voltage capacitor or a complicated phase shift circuit, and has a very simple circuit configuration, so that it is possible to realize miniaturization and cost reduction.

In the fluorescent lamp drive circuit, by controlling the polarization state of the piezoelectric ceramics 4e used in the piezoelectric ceramic transformer 4, the voltage phase of the feedback signal from the feedback electrode 4d of the piezoelectric ceramic transformer 4 becomes Although the phase of the voltage required for high-voltage oscillation by the piezoelectric ceramic transformer 4 is set, instead of this, as shown in FIG. 2, the feedback electrode 4d of the piezoelectric ceramic transformer 4 is used.
And a base of the NPN transistor 3 between the phase shift circuit 8
May be provided. In addition, in FIG.
Parts other than the phase shift circuit 8 are shown with the same symbols as in FIG. At this time, the return electrode 4
The phase of the voltage of the feedback signal from the feedback electrode 4d of the piezoelectric ceramic transformer 4 is required for high voltage oscillation by the piezoelectric ceramic transformer 4 due to the phase shift circuit 8 provided between d and the base of the NPN transistor 3. The phase of the voltage of the feedback signal is shifted so that it becomes the phase of the voltage.

When the phase shift circuit 8 is provided in this way, the circuit becomes complicated as much as the phase shift circuit 8 is required as compared with the above-mentioned fluorescent lamp drive circuit. Similarly, since a high voltage capacitor is not required, the circuit configuration is simpler than that of the conventional fluorescent lamp drive circuit, and the cost can be reduced.

The application of the fluorescent lamp driving circuit to which the present invention is applied is not particularly limited, but the circuit configuration is simple and suitable for downsizing, so that a liquid crystal display with a strict demand for downsizing is used. Is particularly suitable for the backlight.

Next, an embodiment of a piezoelectric ceramic transformer to which the present invention is applied, which is suitable for the above fluorescent lamp driving circuit, will be described with reference to the drawings.

As shown in FIG. 3, the piezoelectric ceramic transformer according to the present embodiment has a rectangular plate-shaped piezoelectric ceramic 11 made of PZT ceramic or the like, and a piezoelectric ceramic 11.
Input electrodes 12 and 13 formed on the upper and lower main surfaces, and an output electrode 14 and a return electrode 15 formed on the end surface of the piezoelectric ceramic 11 on the side far from the input electrodes 12 and 13. .

Here, the input electrodes 12 and 13 extend over the entire width of the main surface of the piezoelectric ceramic 11 and the piezoelectric ceramic 1
It is formed from one end of 1 to a position of about half in the longitudinal direction. On the other hand, the output electrode 14 and the return electrode 15 formed on the end surface of the piezoelectric ceramic 11 are formed such that the area of the output electrode 14 is larger than the area of the return electrode 15. Here, the output electrode 14 and the return electrode 15 are formed through a gap 16 so that the output electrode 14 and the return electrode 15 are not directly connected to each other. Thus, the area of the output electrode 14 and the return electrode 15
By changing the area of the portion, it is possible to control the magnitude of the power obtained from the output electrode 14 and the magnitude of the power obtained from the feedback electrode 15 when the piezoelectric ceramic transformer is driven. That is, by making the area of the output electrode 14 larger than the area of the feedback electrode 15, the electric power obtained from the output electrode 14 becomes large and the electric power obtained from the feedback electrode 15 becomes small.

Further, this piezoelectric ceramic transformer outputs so that the phase of the feedback signal for self-oscillation output from the feedback electrode 15 becomes the phase of the voltage required for high-voltage oscillation by the piezoelectric ceramic transformer. The polarization direction P1 of the piezoelectric ceramic 11 near the working electrode 14 and the polarization direction P2 of the piezoelectric ceramic 11 near the feedback electrode 15 are controlled. That is, the polarization direction P1 of the piezoelectric ceramic 11 near the output electrode 14 and the polarization direction P2 of the piezoelectric ceramic 11 near the feedback electrode 15 are the phases of the feedback signal for self-excited oscillation output from the feedback electrode 15. Are in different directions so that they have the phase of the voltage required for high voltage oscillation by the piezoelectric ceramic transformer. However, the phase shift circuit that shifts the phase of the feedback signal is fed back so that the phase of the feedback signal for self-oscillation output from the feedback electrode 15 becomes the phase of the voltage required for high-voltage oscillation by the piezoelectric ceramic transformer. Needless to say, it is not necessary to control the polarization direction of the piezoelectric ceramic 11 when it is provided in the circuit.

When driving this piezoelectric ceramic transformer, a voltage is applied from the input electrode 12, whereby the piezoelectric ceramic 11 resonates, and as a result, a voltage converted into a high voltage is output from the output electrode 14. It At this time, the feedback electrode 15 outputs a low-power feedback signal required for self-oscillation of the piezoelectric ceramic transformer.

In the piezoelectric ceramic transformer described above, the area of the return electrode 15 is made smaller than the area of the output electrode 14 so that the return electrode 15 is formed.
Although the power from the input electrode 21 is set to be smaller than the power from the output electrode 14, as shown in FIG.
22 is the distance t1 between the return electrode 23 and the input electrode 2
The electric power from the feedback electrode 23 may be made smaller than the electric power from the output electrode 24 by making the distance t2 shorter than the distance t2 from the electrodes 1 and 22 to the output electrode 24.
That is, the output electrode 24 may be formed on one entire end surface of the piezoelectric ceramic 25, and the feedback electrode 23 may be formed on one main surface of the piezoelectric ceramic 25. Here, the return electrode 23 is provided with a gap 26 between the input electrode 21 and the return electrode 23 at a portion on the one main surface of the piezoelectric ceramic 25 where the input electrode 21 is not formed.
To form.

At this time as well, similar to the piezoelectric ceramic transformer described above, the phase of the feedback signal for self-excited oscillation output from the feedback electrode 23 is the phase of the voltage required for high-voltage oscillation by the piezoelectric ceramic transformer. So that the polarization direction P3 of the piezoelectric ceramic 25 near the output electrode 24 and the piezoelectric ceramic 2 near the feedback electrode 23
The polarization direction P4 of 5 may be different from each other.

By the way, the piezoelectric ceramic of the piezoelectric ceramic transformer resonates at the time of driving. At this time, if the wiring drawn out from the electrode formed on the piezoelectric ceramic also vibrates at the same time, the wiring may be broken or the wiring may be broken. Due to the presence, the resonance frequency and output voltage of the piezoelectric ceramic may vary. Therefore, as shown in FIG. 5, the wiring 31 derived from the first input electrode 31 is provided.
a, a wiring 32a derived from the second input electrode 32,
The wiring 33a led out from the output electrode 33 and the wiring 34a led out from the return electrode 34 are preferably led out from the node portion of the piezoelectric ceramic 35 in the primary vibration mode. In this way, the wirings 31 a, 32 from the input electrodes 31, 32, the output electrode 33, and the return electrode 34 are formed.
By pulling out a, 33a, and 34a from the nodes of the primary vibration mode of the piezoelectric ceramic 35, these wirings 31a, 32a, 33a, and 34a do not vibrate when the piezoelectric ceramic 35 resonates. .
As a result, these wirings 31a, 32a,
33a, 34a will not be broken,
The reliability of the piezoelectric ceramic transformer is greatly improved. Further, variations in the resonance frequency and output voltage of the piezoelectric ceramic 35 due to the presence of these wirings 31a, 32a, 33a, 34a are reduced, and the performance of the piezoelectric ceramic transformer is improved.

[0036]

As is apparent from the above description, in the fluorescent lamp driving circuit according to the present invention, a high voltage is supplied to the fluorescent lamp from the output electrode of the piezoelectric ceramic transformer, and at the same time, the piezoelectric ceramic transformer A low-voltage feedback signal is output from the feedback electrode and self-oscillation is performed. Therefore, in this fluorescent lamp drive circuit, it is not necessary to dispose the high voltage capacitor in the feedback circuit, and the cost can be reduced.

Further, in the fluorescent lamp driving circuit according to the present invention, by controlling the polarization direction of the piezoelectric ceramic,
The phase of the self-oscillation feedback signal output from the feedback electrode can be the phase of the voltage required for high-voltage oscillation by the piezoelectric ceramic transformer. Therefore, in this fluorescent lamp drive circuit, it is not necessary to dispose a phase shift circuit in the feedback circuit, and it is possible to realize cost reduction and miniaturization.

Further, since the piezoelectric ceramic transformer according to the present invention is provided with the feedback electrode for outputting the feedback signal in addition to the output electrode, it is independent of the magnitude of the voltage output from the output electrode. , The magnitude of the voltage of the feedback signal can be controlled. Therefore, in this piezoelectric ceramic transformer, by setting the feedback signal output from the feedback electrode of the piezoelectric ceramic transformer to a low voltage, it is not necessary to dispose a high withstand voltage capacitor in the feedback circuit when performing self-excited oscillation, The price can be reduced.

Furthermore, in the piezoelectric ceramic transformer according to the present invention, by controlling the polarization direction of the piezoelectric ceramic, the phase of the feedback signal for self-oscillation output from the feedback electrode can be controlled by the high voltage of the piezoelectric ceramic transformer. It can be the phase of the voltage required for oscillation. Therefore,
In this piezoelectric ceramic transformer, there is no need to dispose a phase shift circuit in the feedback circuit when performing self-excited oscillation, and it is possible to realize cost reduction and downsizing.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration example of a fluorescent lamp drive circuit to which the present invention is applied.

FIG. 2 is a circuit diagram showing another configuration example of a fluorescent lamp drive circuit to which the present invention is applied.

FIG. 3 is a perspective view showing a configuration example of a piezoelectric ceramic transformer to which the present invention is applied.

FIG. 4 is a perspective view showing another configuration example of the piezoelectric ceramic transformer to which the present invention is applied.

FIG. 5 is a perspective view showing another configuration example of the piezoelectric ceramic transformer to which the present invention is applied.

FIG. 6 is a perspective view showing a conventional piezoelectric ceramic transformer.

FIG. 7 is a circuit diagram showing a conventional self-oscillation type fluorescent lamp drive circuit.

FIG. 8 is a circuit diagram showing a conventional separately excited oscillation type fluorescent lamp driving circuit.

[Explanation of symbols]

 1 Power Supply Terminal 2 Fluorescent Lamp 3 NPN Transistor 4 Piezoelectric Ceramic Transformer 4a First Input Electrode 4b Second Input Electrode 4c Output Electrode 4d Feedback Electrode 4e Piezoceramic 5 Coil 6 Resistor 7 Ground Side Terminal

Claims (7)

[Claims] 1. A self-excited oscillation type fluorescent lamp driving circuit using a piezoelectric ceramic transformer in which electrodes are attached to a substantially rectangular plate-shaped piezoelectric ceramic, wherein the piezoelectric ceramic transformer supplies a driving voltage to the fluorescent lamp. And a feedback electrode for outputting a feedback signal for self-oscillation, a fluorescent lamp drive circuit. 2. The return electrode attached to the piezoelectric ceramic is smaller than the output electrode attached to the piezoelectric ceramic.
The described fluorescent lamp drive circuit. 3. The fluorescent lamp drive circuit according to claim 2, wherein a polarization direction of the piezoelectric ceramic near the output electrode is different from a polarization direction of the piezoelectric ceramic near the feedback electrode. 4. The piezoelectric ceramic transformer comprises a pair of input electrodes formed so as to face upper and lower main surfaces of the piezoelectric ceramic, and a distance from the input electrode to the return electrode is equal to the input electrode. 2. The fluorescent lamp drive circuit according to claim 1, wherein the distance is shorter than the distance from the output electrode to the output electrode. 5. The fluorescent lamp drive circuit according to claim 4, wherein the polarization direction of the piezoelectric ceramic near the output electrode is different from the polarization direction of the piezoelectric ceramic near the feedback electrode. 6. A substantially rectangular plate-shaped piezoelectric ceramic, a pair of input electrodes formed on the upper and lower main surfaces of the piezoelectric ceramic so as to face each other, and formed on the end surface of the piezoelectric ceramic far from the input electrode. And a feedback electrode, wherein the output electrode outputs a high voltage and the feedback electrode outputs a feedback signal. 7. The wirings from the pair of input electrodes, the output electrodes, and the return electrodes are led out from the nodes of the primary vibration mode of the piezoelectric ceramic. 6. The piezoelectric ceramic transformer according to item 6.