JPH0787692B2 - High voltage generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high voltage generator used for applying a high DC voltage to a cathode ray tube of a television receiver or a display device, for example.

[Prior art]

Conventionally, there are known two types of high voltage generators called flyback transformers, a section winding type and a coaxial multi-layer winding type, depending on the winding method of the high voltage coil. In the former section winding type, the high voltage coil is a shaft of a high voltage bobbin. Direction is divided into a plurality of high voltage winding blocks and wound, and the latter coaxial multi-layer winding type is one in which the high voltage coil is divided into a plurality of high voltage winding layers in the radial direction of the high voltage bobbin and wound. is there. The coaxial multilayer winding type flyback transformer has recently been put to practical use because it can reduce the output impedance as a single unit and improve the high voltage regulation.

Therefore, a high voltage generator using a coaxial multilayer winding type flyback transformer according to the prior art will be described with reference to FIGS.

First, FIG. 7 shows a coaxial multilayer winding type flyback transformer. In the figure, reference numeral 1 is a flyback transformer, and the flyback transformer 1 is formed by inserting a core 2 formed by abutting a U-shaped core member and one leg of the core 2 into the core 2. A low-pressure bobbin 3 provided, a low-voltage coil 4 section-wound around the outer periphery of the low-pressure bobbin 3, a high-pressure bobbin 5 provided so as to be fitted on the low-pressure bobbin 3, and an interlayer on the outer periphery of the high-pressure bobbin 5. High-voltage coil 7 consisting of five high-voltage winding layers 7A, 7B, ... 7E wound in coaxial multi-layers via paper 6, 6, ... And high-voltage winding layers 7A, 7B, ... The high voltage diode 8 is composed of five high voltage diodes 8A, 8B, ... 8E connected to each other.

Further, FIG. 8 shows the entire circuit configuration. In FIG. 8, “•” attached to the low voltage coil 4 and each of the high voltage winding layers 7A to 7E indicates a winding end. The high voltage side end of the low voltage coil 4 is connected to the horizontal deflection circuit 9. The horizontal deflection circuit 9 includes a horizontal output transistor 10, which is an NPN transistor, a damper diode 11, and a resonance capacitor 1.
2, a horizontal deflection coil 13 of a deflection yoke, an S-shaped correction capacitor 14, etc., the collector side of the transistor 10 is connected to the high voltage end side of the low voltage coil 4, and the emitter is grounded. Further, the low voltage end side of the low voltage coil 4 is connected to a flyback power supply 15 for applying a DC voltage thereto. On the other hand, in the high-voltage coil 7, the high-voltage winding layer 7A on the lowest pressure side is connected to an ABL circuit (automatic brightness limitter) or ground, and the high-pressure winding layer 7E on the highest pressure side.
Is connected to the anode terminal 17A of the cathode ray tube 17 from the output high voltage diode 8E via the high voltage cable 16. In addition, 18 is a fixed resistor on the high voltage output end side, 19 is a focus volume resistor, and these resistors 18 and 19 are provided in series between the high voltage output end of the high voltage coil 7 and the ground.

In the high voltage generator configured as above, a basic pulse is applied to the base of the transistor 10 from a horizontal drive circuit (not shown), so that a collector pulse (flyback pulse) is generated from the collector of the transistor 10. It is output to the low voltage coil 4. As a result, a high voltage determined by the number of coil turns is induced in each winding layer 7A to 7E of the high-voltage coil 7, and the high-voltage diodes 8A to 8E additionally rectify each of these high-voltages.
As shown in the figure, a DC high voltage having a high voltage output voltage E _H and a high voltage output current I _H is output to the cathode ray tube 17.

When the flyback transformer 1 is a coaxial multi-layer winding as shown in FIG. 6 and the number of windings is the same, the potential difference between the winding layers 7A to 7E of the high-voltage coil 7 becomes zero in AC. , Have the same output waveform. Therefore, each winding layer
Between 7A and 7E, the insulation treatment using only the DC electronic difference is sufficient, and the interlayer paper 6 may be very thin.

On the other hand, between each of the high voltage winding layers 7A to 7E, e _H = Δe _H × N _H (1) However, Δe _H : Generated voltage per turn N _H : Winding of the winding layers 7A to 7E A voltage expressed as a number is generated. Therefore, the AC penetration withstand voltage applied to the distance L (see FIG. 7) between the high voltage side end of the winding layer 7A on the lowest pressure side and the low voltage coil 4 becomes e _H1 when the AC withstand voltage of the low voltage coil 4 is ignored. , The distance L is the voltage e _H1
Material and distance to withstand However, when the high voltage coil 7 is divided into five layers, e _H ≈5.4 kV and the distance L becomes a small value even when the high voltage output voltage E _H is 27 kV.

As described above, the finished outer diameter R (see FIG. 7) of the outermost layer side high voltage winding 7E of the flyback transformer 1 is reduced, and as a result, the leakage inductance of the high voltage coil 7 can be reduced. Therefore, when the flyback transformer is the coaxial multi-layer winding type shown in FIG. 7, the high voltage output characteristic is 9th.
In the state of the characteristic (a) in the figure, the voltage drop can be reduced as much as the leakage inductance is smaller than the characteristic (b) in the case of the section winding type.

However, with this alone, the high voltage output current I _H is 0 to 200μ.
Since a large high voltage fluctuation occurs in the range of A, by inserting the fixed resistor 18 and the focus volume resistor 19 in series between the high voltage output terminal and the ground, and shunting a part of the high voltage output current I _H. , The high-pressure fluctuation is improved and the characteristics (c) shown in Fig. 10 are devised. In addition,
Since loss of these resistors 18 and 19 is too small increases are diverted about 10% of the normal high voltage output current I _H as the current i _H. Now, the total resistance value of these resistors 18 and 19 is 260
It is set as MΩ, and when a current of i _H = 100 μA is passed through this resistor, it is discarded as an energy loss of 2.6 W.

Therefore, if the output impedance due to the characteristic (a) in Fig. 9 is Z ₀₁ , On the other hand, if the output impedance due to the characteristic (c) in Fig. 10 is Z ₀₂ , And has been largely improved.

[Problems to be solved by the invention]

However, the above-mentioned prior art has improved the high-voltage regulation by improving the characteristics of the flyback transformer 1 as a whole to lower the output impedance. However, the output impedance of the flyback transformer 1 as a single unit is limited to about 1.2 MΩ, and there is a problem that it cannot meet the recent severe needs like a display device.

That is, in the characteristic (c) of FIG. 10, the voltage drop ΔE _H when the high voltage output current I _H changes from 0 to 1000 μA is ΔE _H = 1000 μA × 1.2 MΩ = 1.2 kV (4). This is generally a high pressure regulation R _e , As Is equivalent to a change of 4.8%.

The present invention has been made in view of the above-mentioned problems of the prior art, and changes in the high voltage output voltage due to changes in the high voltage output current,
A so-called high voltage load fluctuation is added to the high voltage output voltage by adding the peak value component of the flyback pulse induced at the high voltage side end of the additional coil to the high voltage output voltage to stabilize the high voltage output voltage. It is to provide a voltage generator.

[Means for solving problems]

In order to solve the above problems, a high voltage generator according to the present invention is wound around a low voltage coil and an outer peripheral side of the low voltage coil, and generates a high voltage output by inputting a pulse signal to the low voltage coil. In a high-voltage generator equipped with a high-voltage coil, provided by winding on the high-voltage side of the low-voltage coil, from the high-voltage end side, when the high-voltage output current of the high-voltage coil changes to the maximum within the variable range. An additional coil for generating an output voltage substantially equal to the change in the high voltage output voltage; and a high voltage output change detecting means for detecting a change in the high voltage output voltage or the high voltage output current by the high voltage coil,
Based on the change detection signal by the high-voltage output change detection means,
When the high voltage output current is zero, the addition of the output voltage from the additional coil to the high voltage coil is set to zero,
When the high-voltage output current is maximum, the addition of the output voltage from the additional coil to the high-voltage coil is maximized, and when the high-voltage output current is between zero and maximum, the additional coil is added to the high-voltage coil. And a control means for adding the added voltage of the output voltage from the coil to the voltage drop of the high voltage output voltage, and applying the added voltage of the output voltage from the added control means to the low voltage side of the high voltage coil. is there.

[Action]

With the above configuration, an additional coil is wound around the high voltage side of the low voltage coil, and an output voltage equal to the change in the high voltage output voltage due to the high voltage coil can be generated from the high voltage end side of the additional coil. There is.

Here, the high-voltage output voltage output from the high-voltage coil fluctuates in accordance with the high-voltage output current, but the change in the high-voltage output voltage output from the high-voltage coil is detected by the high-voltage output change detection means. The high voltage output voltage is maximum when the high voltage output current detected by the high voltage output change detecting means is zero. Therefore, the change detection signal for this maximum high voltage output voltage is input to the addition control means as zero.
As a result, the addition control means sets the added amount of the output voltage of the additional coil to zero based on the change detection signal, and applies it to the low voltage side of the high voltage coil.

Further, when the high voltage output current detected by the high voltage output change detecting means is maximum, the high voltage output voltage is the lowest, and the change detection signal for this lowest high voltage output voltage is inputted to the addition control means as the lowest. As a result, the addition control means applies the addition to the low voltage side of the high voltage coil with the maximum addition of the output voltage of the additional coil based on the change detection signal.

Further, when the high-voltage output current detected by the high-voltage output change detecting means is in the middle between zero and maximum, the high-voltage output voltage is in the middle. The high-voltage output voltage in the middle, that is, the change detection signal for the voltage drop. Is input to the addition control means. As a result, the addition control means adds and applies the addition of the output voltage from the additional coil to the low voltage side of the high voltage coil as a voltage drop based on the change detection signal.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. The same components as those of the above-described conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

First, FIGS. 1 to 5 show a first embodiment of the present invention.

In the figure, reference numeral 21 is a coaxial multilayer winding type flyback transformer used in this embodiment. The flyback transformer 21 is composed of a core 2, a low voltage coil 4, a high voltage coil 7, a high voltage diode 8 and the like as in the prior art. There is no change in terms of the structure (note that in FIG. 1, the high voltage coil 7,
The high voltage diode 8 is shown in a simplified manner). However, this embodiment is different in that the additional coil 22 is wound around the low voltage bobbin 3.

Here, the additional coil 22 is wound around the low-voltage bobbin 3 in the same winding direction as the low-voltage coil 4 so as to be coaxially wound around the outer periphery of the low-voltage coil 4 or continuously with the low-voltage coil 4 in the axial direction of the low-voltage bobbin 3. Is wound like. In addition,
The additional coil 22 may be wound in the reverse direction, in which case a tap is provided in the middle of the low voltage coil 4 to obtain an equivalent action. The low-voltage side of the additional coil 22 is connected in series with the high-voltage side end of the low-voltage coil 4 at the connection point a, and
It is connected to the collector side of a transistor 10 that constitutes the horizontal deflection circuit 9, and the high voltage side is connected to the anode of a diode 30 that constitutes an addition control circuit 24, which will be described later.

Therefore, at the high-voltage side end of the additional coil 22, e _N2 = Δe _L × (N ₁ + N ₂ ) + E _B (7) where Δe _L : generated voltage per turn N ₁ : low-voltage coil 4 Number of windings N ₂ : Additional coil 22 Number of windings E _B : Generates a pulse voltage represented by the power supply voltage of the flyback power supply 15, and outputs this output voltage
e _N2 has a waveform as shown in FIG. 2, in which the positive part is e ₀ and the negative part is e _0r . Moreover, of the output voltage e _N2 generated by the additional coil 22, the positive portion e ₀ + E
_B is the maximum value within a variable range of 0 to 1000 μA, for example, when the high voltage output current I _H changes to I _Hm = 1000 μA, the change in the high voltage output voltage E _H , that is, a voltage value almost equal to ΔE _H = 1.2 kV. Is set to. It is needless to say that the generated current flows from the low voltage coil 4 to the additional coil 22 in the direction indicated by the arrow in the figure.

Reference numeral 23 is a variable resistance for voltage change detection which constitutes the high voltage output change detecting means according to this embodiment. The variable resistance 23 is a fixed resistance 1 between the high voltage side output end of the high voltage coil 7 and the ground.
8 、 Connected to the focus volume resistor 19 in series. The variable resistor 23 generates a detection voltage e _H at its sliding end according to the change in the high voltage output voltage E _H , and outputs it to the non-inverting input terminal side of an error amplifier 25, which will be described later.

Reference numeral 24 is an addition control circuit which constitutes the addition control means according to the present embodiment. The addition control circuit 24 includes an error amplifier 25 including a differential amplifier, first and second NPN type transistors 26 and 27, first and second Two
Of resistors 28, 29 and first and second diodes 30, 31. The inverting input terminal side of the error amplifier 25 is connected to the reference power source 32 that supplies the reference voltage e _S , the non-inverting input terminal side is connected to the variable resistor 23, and the output terminal side is a transistor.
Connected with 26 bases. Also, the transistor 26
The emitter is grounded and the collector is connected to the base of the transistor 27 through the resistor 28. The anode side of the first diode 30 is connected to the high-voltage side of the additional coil 22, and the cathode side is connected to the collector of the transistor 27 and also to the base via the resistor 29. Further, the emitter of the transistor 27 is connected to the lowest pressure side end of the high voltage coil 7 and the anode of the second diode 31, and the cathode of the diode 31 is connected to the base.

Here, the error amplifier 25 receives the voltages e _H and e _S from the variable resistor 23 and the reference power source 32, respectively, but the high voltage output current I _H
Since the detection voltage e _H becomes the minimum voltage e _Hl when becomes the maximum value I _Hm , the variable resistor 23 is adjusted so that e _Hl = e _S (8).

The first resistor 28 is a current protection resistor for the first transistor 26, and the second resistor 29 gives a base applied voltage to the transistor 27, and has a resistance value extremely larger than that of the resistor 28. There is. Further, the first diode 30 removes the negative part e _0r of the output voltage of the additional coil 22, and the second diode 31 is a diode for protecting the second transistor 27 from destruction.

Then, according to the change of the shunted current i _H , the error amplifier
Since the detection voltage e _H applied to 25 changes, the states of the first and second transistors 26 and 27 change accordingly. Now, cathode of diode 30, resistor 29, transistor 27
The connection point with the collector of is A, the emitter of the transistor 27, the anode of the diode 31, and the capacitor 3 described later.
3 and the connection point of the low-voltage side end of the high-voltage coil 7 is B, the connection point A has a third position in accordance with the change in the high-voltage output current I _H.
The voltage e ₁ shown in (a) to (c) of FIG.
The DC output voltage e ₂ shown in FIGS. 4A to 4C is generated, and the output voltage e ₂ is added to the high voltage coil 7.

Further, 33 is a capacitor provided between the connection point B and the ground to constitute the smoothing circuit means according to the present embodiment. The capacitor 33 smoothes the output voltage from the transistor 27, and the DC output shown in FIG. It is designed to obtain a voltage e ₂ .

In the figure, 34 is a diode provided in parallel with the capacitor 33 between the connection point B and the ground. The diode 34 is provided when the transistor 27 is cut off, that is, when the DC output voltage e ₂ is zero. The lowest pressure side end of is connected to the ground to allow the flow of the high voltage output current I _H.

In addition, 35 is a video amplifier circuit, 36 is a resistor for deriving an ABL signal,
The video amplifier circuit 35 and the resistor 36 are the cathode of the cathode ray tube 17.
It is connected in series between 17B and ground so that a high voltage output current I _H flows toward ground, and the voltage across the resistor 36 is output to the ABL circuit as an ABL signal. .

The present embodiment is configured in this way, and its operation will be described next.

First, by applying a collector pulse from the horizontal deflection circuit 9 to the low voltage coil 4, a high voltage based on the equation (1) is induced in each winding layer 7A to 7E of the high voltage coil 7, while the additional coil 22 A pulse voltage based on the equation (7) is also generated on the high voltage side and induced as a flyback pulse as shown in FIG.

Now, in such a state, a process of adding the high voltage output voltage E _H according to the change of the high voltage output current I _H will be described.

First, when the high voltage output current I _H is I _H = 0, the voltage drop due to the output impedance Z ₀ of the high voltage generating circuit is zero,
The high voltage output voltage E _H is maximum. Therefore, the variable resistance
The detection voltage e _H output from the sliding end of 23 is the maximum value e _Hm , and the value of the output voltage e _C is output from the error amplifier 25 to the base of the transistor 26 as the maximum value.
26 is fully conducting and its internal resistance is almost zero. Therefore, in this state, the voltage shown in FIG. 3 (a) is generated on the cathode side (connection point A) of the diode 30, but this voltage flows to the ground via the resistors 29 and 28 and the transistor 26, and the second voltage The transistor 27 of is in the cutoff state. As a result, the voltage on the emitter side of the transistor 27 is zero,
The DC output voltage e _{20 at} the connection point B is also zero, and as shown in FIG.
It is a characteristic of.

Therefore, in this state, the low-voltage side of the high-voltage coil 7 is only connected to the ground via the diode 34, and the high voltage induced in each winding layer 7A-7E is the same as that in the prior art, and each diode 8A- By 8E, Is added and rectified to generate a high voltage output voltage of, for example, E _H = 26.1 kV.

Next, conversely to the above, when I _H = I _Hm at which the high voltage output current I _H has the maximum value of 1000 μA, the voltage drop Z ₀ I _Hm of the high voltage output voltage E _H is about to become the maximum.

However, in the present embodiment, the detection voltage e _H by the variable resistor 23 becomes the minimum voltage e _Hl when the high voltage output current I _H is maximum, and the reference voltage e _S input to the error amplifier 25 has the relationship shown in the equation (8). Therefore, in this state, the output voltage e _C from the error amplifier 25 to the transistor 26 becomes zero, and the transistor 26
Is completely shut off. As a result, the base of transistor 27 to the voltage e ₀ + E _B shown in FIG. 3 (b) acting through resistor 29, brought into conduction the transistor 27, the voltage e ₀ + E suffering from the collector at the same time _B flows from the emitter to the capacitor 33 and is smoothed, and the DC output voltage e ₂₂ shown in FIG. Further, since the connection point B is connected to the base of the transistor 27 through the diode 31, this DC output voltage e ₂ acts on the transistor 27. Further, since the connection point B is also connected to the connection point A via the diode 31 and the resistor 29, the connection point A has a voltage waveform as shown in FIG.

Thus, in this embodiment, the high voltage output voltage E _H generated in the high voltage cable 16 is Next, by setting the _{e 22 ≒ e 12 ≒ e 0} + E B ≒ Z 0 I Hm ...... (11) is high output voltage e _n2 additional coil 22 as holds, that holds the (9) Therefore, the voltage drop can be added and controlled.

Further, in the middle of the high voltage output current I _H is zero and a maximum value, the output voltage e _C from the error amplifier 25 becomes a value corresponding to the high voltage output current, the first transistor 26 to the output voltage e _C The second transistor 27 has a corresponding internal resistance, and the second transistor 27 becomes conductive at a voltage equal to or higher than the voltage divided by the resistances 29 and 28 and the internal resistance of the first transistor 26. Therefore, even in this state, the connection point A has the voltage waveform shown in FIG. 3 (b), and the connection point B has the DC output voltage shown in FIG. 4 (b), which is the same as the equations (10) and (11). Control the addition of the voltage drop.

As described above, in the present embodiment, the voltage drop amount of the high voltage output voltage is added and controlled in accordance with the change of the high voltage output current. Therefore, the high voltage output voltage as shown in FIG. Can obtain extremely stable characteristics,
Regulation can be improved.

Next, FIG. 6 shows a second embodiment of the present invention, in which the same components as those in the first embodiment described above are designated by the same reference numerals and the description thereof is omitted.

Therefore, the feature of this embodiment is that the variable resistor 23 in the first embodiment is eliminated, and the change in the high voltage output current I _H is changed by using the resistor 36 for deriving the ABL signal, e ′ _H = R _S × I _H (12) However, R _S : It is directly derived as the resistance value of the resistor 36, and this detection voltage e ′ _H is used as the error amplifier 25.
Of the error amplifier 25 and the non-inverting input terminal side of the error amplifier 25 is set to the ground potential.

Although the present embodiment is configured in this way, the high-voltage output current I _H from the flyback transformer 21 flows to the ground via the high-voltage cable 16, the cathode ray tube 17, the video amplifier circuit 35, and the resistor 36. Therefore, when the high-voltage output current I _H is zero, the detection voltage e ′ _H is also zero, so that the error amplifier 25 causes the transistor
When the output voltage e _C to 26 becomes maximum and the transistor 26 is brought into full conduction, and conversely the high voltage output current I _H becomes the maximum value,
By shutting off the transistor 26, the high voltage output characteristic shown in FIG. 5 can be obtained as in the first embodiment.

Although the coaxial multi-layer winding type has been described as the flyback transformer in the embodiment, the flyback transformer may be applied to the section winding type flyback transformer.

Furthermore, it goes without saying that the addition control circuit 24 is not limited to the circuit configuration of the embodiment.

〔The invention's effect〕

The high-voltage generator according to the present invention is as described in detail above, and an additional coil is provided on the high-voltage side of the low-voltage coil to generate an output voltage equal to the change in the high-voltage output voltage. The change is detected as a change detection signal by the high-voltage output change detection means, and the addition control means changes the addition amount of the output voltage additionally applied to the low-voltage side of the high-voltage coil from zero to the maximum based on this change detection signal. By controlling, the high voltage output voltage can be stabilized at a substantially constant value regardless of the change in the high voltage output current. And
This means that the output impedance is substantially lowered, the high voltage regulation can be remarkably improved, and the cathode ray tube can be provided with a high quality screen. Moreover, since the addition control means is switch-controlled, there is little loss, and the additional coil only has to be wound so as to extend it as a part of the low-voltage coil, so that it is easy to manufacture. Play.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 5 show a first embodiment of the present invention, FIG. 1 is a circuit configuration diagram of this embodiment, and FIG. 2 is a high-voltage side output voltage waveform of an additional coil. 3 and 4 are voltage waveform diagrams of the connection point A in FIG. 1, FIG. 3 (a) is a voltage waveform diagram when the high voltage output current I _H = 0, and FIG. 3 (b) is a high voltage output. Voltage waveform diagram when current I _H = medium level, FIG. 3 (C) is voltage waveform diagram when high voltage output current I _H = maximum, and FIG. 4 is voltage waveform diagram of connection point B in FIG. FIG. 4 (a) is a voltage waveform diagram when the high voltage output current I _H = 0, FIG. 4 (b) is a voltage waveform diagram when the high voltage output current I _H = medium level, and FIG. ) Is the high voltage output current I _H =
Voltage waveform diagram at maximum, FIG. 5 is a high voltage output current-high voltage output voltage characteristic diagram obtained by this embodiment, FIG. 6 is a circuit configuration diagram according to the second embodiment of the present invention, FIG. Or first
FIG. 10 relates to the prior art, FIG. 7 is a longitudinal sectional view of a coaxial multi-layer winding type flyback transformer, FIG. 8 is a circuit configuration diagram of a high voltage generating circuit according to the prior art, and FIG. High-voltage output current-high-voltage output voltage characteristic diagram by transformer and section winding type flyback transformer,
FIG. 10 is a high voltage output current-high voltage output voltage characteristic diagram in the case where a fixed resistor and a focus resistor are provided between the high voltage output side and the ground in order to improve the high voltage fluctuation. 2 ... Core, 3 ... Low-voltage bobbin, 4 ... Low-voltage coil, 5
...... High voltage bobbin, 7 ...... High voltage coil, 8 ...... High voltage diode, 9 ...... Horizontal deflection circuit, 16 ...... High voltage cable, 17 ...
… Cathode ray tube, 18 …… fixed resistance, 19 …… focus volume resistance, 21 …… flyback transformer, 22 …… additional coil, 23 …… variable resistance, 24 …… addition control circuit, 25 …… error amplifier, 26 , 27 …… transistor, 28,29,36 …… resistor, 30,31,34 …… diode, 32 …… reference power supply, 33 ……
Capacitors.

Claims (1)

[Claims] 1. A high-voltage generator comprising a low-voltage coil and a high-voltage coil wound around the outer periphery of the low-voltage coil and generating a high-voltage output by inputting a pulse signal to the low-voltage coil, It is provided by winding it on the high voltage side of the low voltage coil, and from its high voltage end side, generates an output voltage that is approximately equal to the change in the high voltage output voltage when the high voltage output current of the high voltage coil changes to the maximum within the variable range. An additional coil, a high-voltage output change detecting means for detecting a change in the high-voltage output voltage or the high-voltage output current by the high-voltage coil, and the addition when the high-voltage output current is zero based on a change detection signal by the high-voltage output change detecting means. The added voltage of the output voltage from the additional coil to the high voltage coil is set to zero, and when the high voltage output current is the maximum, the additional voltage is added from the additional coil to the high voltage coil. When the high voltage output current is in the middle between zero and the maximum, the addition of the output voltage from the additional coil to the high voltage coil is defined as the voltage drop of the high voltage output voltage. A high-voltage generating device, characterized in that it is configured to apply the addition of the output voltage from the addition control means to the low-voltage side of the high-voltage coil.