JPS5838948B2 - Koden Atsuhatsu Seisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high voltage generator using a piezoelectric transformer.

In general, piezoelectric transformers are known to have poor regulation, and for this reason, in high voltage generators using conventional piezoelectric transformers, when the load is opened, the output voltage rises to several tens of kilovolts, and the device itself In addition to posing a danger to the piezoelectric transformer, it also has the drawback of damaging the piezoelectric transformer.

The present invention relates to a high voltage generator aimed at eliminating the above-mentioned drawbacks.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, 1 is a piezoelectric transformer, which includes a pair of drive electrodes 11, 12 and an output electrode 13.

An amplification circuit 2 is connected to one drive electrode 11 of the piezoelectric transformer 1 , and a phase adjustment circuit 3 is connected to the other drive electrode 12 .

The amplifier circuit 22 and the phase adjustment circuit 3 constitute a self-excited oscillation circuit, and the phase adjustment circuit 3 includes a half-wave rectifier circuit 41 and an NPN transistor 42 connected to the output side of the half-wave rectifier circuit 41. A stabilizing circuit 4 is connected to a circuit having constant voltage characteristics including resistors 43 and 44.

5 is a rectifier circuit connected to the output electrode 13 of the piezoelectric transformer 1, and 6 is a load connected to the output side of the rectifier circuit 5.

The operating state of the high voltage generator having such a configuration will be explained below.

An input is applied to the base of the transistor 21 of the amplifier 2 connected to the drive electrode 11 of the piezoelectric transformer 1 for amplification, and the signal is supplied to the piezoelectric transformer 1 via the transformer 22 to drive the piezoelectric transformer 1.

An output voltage is generated from the output electrode 13 by driving the piezoelectric transformer 1 , which is rectified into a high DC voltage by the rectifier circuit 5 and sent to the load 6 .

At this time, a voltage is generated in the coil 31 of the phase adjustment circuit 3 connected to the drive electrode 12 of the piezoelectric transformer 1, and this voltage induces a voltage in the coil 32 of the phase adjustment circuit 3, causing oscillation and self-excitation. Configure an oscillation circuit.

Here, the coil 33 of the phase adjustment circuit 3 determines the resonance frequency of the self-excited oscillation circuit. A half-wave rectifier circuit 41 of the stabilizing circuit 4 is connected in parallel to the resonant circuit K from the capacitor 34, and an NPN l-transistor is connected between the output side terminals a and a' of the half-wave rectifier circuit 41. 42 is connected between the base and collector with resistors 43 and 44.

In this case, the NPN transistor 42 and the resistor 43,44
As shown in FIG. 2, this constitutes a circuit having constant voltage characteristics in which the current increases rapidly when a certain set voltage (1) is exceeded.

Now, the load 6 connected to the output electrode 13 of the piezoelectric transformer 1
The voltage generated in the resonant circuit K of the phase adjustment circuit 3 increases as the voltage changes and approaches the open state, or as the power supply voltage increases, and when the value exceeds ■1, the current increases rapidly. The equivalent resistance of the stabilizing circuit 4 changes in the direction of decreasing, lowering the Q of the resonant circuit, and as a result, the resonant frequency is controlled, and the phase of the drive frequency of the piezoelectric transformer 1 is changed, so that the drive frequency is increased. It deviates from the natural oscillation frequency of the transformer itself, and the output voltage decreases (in other words, is maintained at a constant value).

Also, resistors 43 and 44 connected to the transistor 42
The output voltage can be similarly controlled by changing the ratio.

As described above, according to the high voltage generator of the present invention, a self-excited oscillation circuit is configured by connecting an amplifying circuit and a two-phase adjustment circuit between the drive electrodes of a piezoelectric transformer, and a rectifier circuit and a rectifier circuit are connected to the phase adjustment circuit. A stabilizing circuit consisting of a circuit with constant voltage characteristics connected to the output side of the rectifier circuit, which controls the resonant frequency of the resonant circuit of the phase adjustment circuit in response to fluctuations in the load or power supply voltage. By changing the phase of the drive frequency of the piezoelectric transformer, it is possible to always obtain stable output characteristics when the load is open or when the power supply voltage increases, and the output voltage value can be set arbitrarily. There is no risk of damage to the piezoelectric transformer, etc.

In one embodiment of the present invention, a half-wave rectifier circuit, an NPN transistor, and a resistor were used as the stabilizing circuit connected to the phase adjustment circuit. A rectification circuit, a full-wave rectification circuit, etc. may be applied, and it goes without saying that a PNP I-transistor can be used as the transistor.

In addition, although we have described the case in which a transistor and a resistor are connected between the output side terminals a and a' of the rectifier circuit of the stabilizing circuit, if the circuit is configured to have constant voltage characteristics as shown in Figure 2, then Not limited to the examples, for example,
As shown in FIG. 3, a Zener diode 45 may be connected to the base of the transistor 42, or as shown in FIG. Instead of the resistors 43 and 44, only the Zener diode 45 may be connected.

Here, when only Zener diodes are connected, the same effect can be obtained by using Zener diodes with different characteristics for each desired output voltage.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the high voltage generator of the present invention;
FIG. 2 is a voltage-current characteristic curve diagram of the stabilizing circuit, and FIGS. 3 and 4 are circuit diagrams of other embodiments of the stabilizing circuit. 1... Piezoelectric transformer, 2... Amplifying circuit, 3... Phase adjustment circuit, 4... Stabilization circuit, 5... Rectifier circuit, 6...Load.

Claims (1)

[Claims] 1. A voltage transformer, an amplification circuit and a phase adjustment circuit connected to both drive electrodes of the voltage transformer, a rectifier circuit connected to the output electrode of the voltage transformer, and a load connected to the output side of the rectifier circuit. A high voltage generator comprising: a stabilizing circuit comprising a rectifier circuit and a circuit having constant voltage characteristics connected to the output side of the rectifier circuit connected to the phase adjustment circuit; A high voltage generator characterized in that the output voltage of the load is controlled in response to fluctuations in the load or power supply voltage by changing the phase.