JPH0547493A - Inverter type x-ray high voltage device - Google Patents

Abstract

PURPOSE:To improve X-ray output and the ray quality in an inverter type X-ray high voltage device by suppressing a drop, pulsation, fluctuation in tube voltage due to dropping of inverter input voltage generated each time the inverter is switched, and whereby stabilizing the tube voltage. CONSTITUTION:A phase setting circuit 9 for determining operational phase of a transistor of an inverter 2 based on setting signal of such as tube voltage and tube current, a phase control circuit 10 for reversing the transistors of right string as well as of left string of the inverter 2, and for having them alternately worked, and a capacitor 7 serving as an input voltage fluctuation suppression means for compensating dropping of input voltage of the inverter, or a serial connected body between the capacitor 7 and a resistance 8, are provided in an inverter-type X-ray high voltage device. The size and the weight of the entire device are thus reduced, and the output voltage to the load in a wide region is stably controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses an inverter for X
The present invention relates to an inverter type high voltage device that applies a high voltage to a wire tube.

[0002]

2. Description of the Related Art In general, an inverter type X-ray high voltage apparatus includes an inverter for converting a DC power supply voltage into a high frequency AC, a high voltage transformer for boosting the output voltage of the inverter, and an output voltage of the high voltage transformer. And an X-ray tube to which the output voltage of the rectifier circuit is applied.

In order to reduce the size and weight of such an X-ray high-voltage device, it is most effective to make the above high-voltage transformer small and lightweight. Then, by increasing the frequency of the input voltage to the high voltage transformer, it is possible to reduce the size and weight of the high voltage transformer. Then, as a means for increasing the frequency of the input to such a high voltage transformer, there is conventionally one using a series resonance type inverter disclosed in US Pat. No. 4,225,788. This utilizes the resonance of the leakage inductance of the high-voltage transformer and the resonance capacitor connected in series with it, and controls the frequency of the inverter to control the voltage supplied to the X-ray tube as a load. It is supposed to do. Also,
As described in Japanese Patent Laid-Open No. 63-190556, the inverter current is cut off and the output voltage is controlled by providing a phase difference between ON and OFF of two sets of opposing switching elements of the resonant inverter. There is also.

However, in the above-mentioned US Pat. No. 4,225,788, when the inverter frequency is lowered to reduce the output, the time integral value of the voltage applied to the high voltage transformer increases. , There is a limit to miniaturization of high voltage transformers. This is disclosed in JP-A-63-1.
Smaller ones are possible with the method described in 90556. FIG. 5 is a circuit diagram of an X-ray high voltage apparatus according to the method described in JP-A-63-190556. This X-ray high-voltage device is a DC power supply 1 such as a secondary battery.
It has an inverter 2, a high-voltage transformer 3, a resonance capacitor 6, a rectifier 4, and an X-ray tube 5.

The inverter 2 converts direct current from the direct current power source 1 into alternating current, and is a transistor Tr ₁ as a first switch connected to the positive electrode of the direct current power source _1.
And a first series connection body composed of a transistor Tr ₂ as a second switch connected to the negative electrode thereof, a transistor Tr ₃ as a third switch provided in parallel with the transistor Tr ₁ and the transistor Tr ₂ , and It is composed of a second series connection body composed of a transistor Tr ₄ as a fourth switch, and diodes D _{1 to} D ₄ respectively connected in antiparallel to the respective transistors Tr _{1 to} Tr ₄ . Each of the above transistors Tr ₁ to Tr ₄ is adapted to turn on by passing a respective base currents. Further, each of the transistors Tr ₁ to Tr ₄ is omitted here but the snubber circuit is connected.

The high-voltage transformer 3 is connected to the output side of the inverter 2 and boosts the output voltage from the inverter 2. The high-voltage transformer 3 has a predetermined turn ratio and has a leakage inductance Ls and a stray capacitance Cs. ing. A resonant capacitor 6 is connected in series to the primary winding of the high voltage transformer 3. The capacitance Cr of the resonance capacitor 6 and the leakage inductance Ls of the high voltage transformer 3 connected in series with the primary winding of the high voltage transformer 3 are used as a resonance element. In order to achieve series resonance, the stray capacitance Cs of the high voltage transformer 3 is set to a value much smaller than the electrostatic capacitance Cr of the resonance capacitor 6. Rectifier 4, the output voltage from the high voltage transformer 3 and converts the direct current to full-wave rectification, four diodes D ₅ ~
It consists of D ₈ . Then, on the output side of the rectifier 4, X
The wire tube 5 is connected. Further, Ch is the capacitance of a high voltage cable for applying the output voltage of the rectifier 4 to the X-ray tube 5, and smoothes the output voltage from the rectifier 4.

The transistor Tr ₁ as the first switch and the transistor Tr ₂ as the second switch of the inverter 2 are alternately turned on with a phase difference of 180 ° at the operating frequency of the inverter 2, with turning the transistor Tr ₃ of the third switch alternately with a phase difference of the transistor Tr ₄ also similarly 180 ° as the fourth switch, the fourth transistor Tr ₄ from the first transistor Tr ₁ is turned on Turn-on phase difference and second transistor Tr ₂
The power supplied to the X-ray tube 5 is controlled by appropriately changing the phase difference in which the third transistor Tr ₃ is turned on after turning on.

Next, the operation of controlling the output power of the X-ray high-voltage apparatus configured as described above will be described with reference to FIG. As shown in FIGS. 6A to 6D, the operating phase of each of the transistors Tr _{1 to} Tr ₄ of the inverter 2 is such that the transistor Tr ₁ and the transistor Tr ₂ are alternately turned on with a phase difference of 180 °, and the transistor Tr ₄ is turned on. And transistor Tr ₃ is 18
The transistors T are turned on alternately with a phase difference of 0 °.
The phase difference in which the transistor Tr ₄ is turned on after r ₁ is turned on is α, and the phase difference in which the transistor Tr ₃ is turned on after the transistor Tr ₂ is turned on is also α.

First, at time Tb _{1 in} FIG. 6, the transistor Tr ₁ and the transistor Tr ₃ are turned on, and the resonance current it is the leakage inductance Ls → resonance capacitor 6 → diode D ₁ → transistor due to the energy of the leakage inductance Ls. Tr ₃ → (rectifier 4, electrostatic capacity Ch of cable and X-ray tube 5) → flow through a circuit of leakage inductance Ls. Therefore, as shown in FIG.
Negative current i ₁ flows (e), the the third arm 2c flows positive current i ₃ as shown in FIG. 6 (h). Then, as the energy of the leakage inductance Ls decreases, as shown in FIG.
t approaches zero. Here, the transistor Tr
_In order to simply describe the state in which the resonance current it flows in two circuits after ₃ , the transistor Tr ₃ →
(Rectifier 4, capacitance Ch of cable and X-ray tube 5) →
It is expressed as the leakage inductance Ls.

Next, at time Tb ₂ , as shown in FIG. 6 (i), after the resonance current it becomes zero, the leakage inductance Ls → (rectifier 4, cable capacitances Ch and X).
Line tube 5) → Diode D ₃ → Transistor Tr ₁ → Resonant capacitor 6 → Leakage inductance Ls flows through the circuit, leakage inductance Ls and capacitance C of resonance capacitor 6
It increases while drawing an arc of the resonance frequency determined by r and. At this time, a positive current i ₁ begins to flow in the first arm 2a as shown in FIG. 6 (e), and a negative current i ₃ in the third arm 2c as shown in FIG. 6 (h). It begins to flow.

Next, at time Tb ₃ , the transistor Tr ₃ is turned off as shown in FIG.
The transistor Tr ₄ is turned on as shown in FIG. Then,
As shown in FIGS. 6A and 6B, both the transistor Tr ₁ and the transistor Tr ₄ are turned on, and when the transistor Tr ₄ is turned on, the diode D ₃ is reverse-biased and turned off. Therefore, the resonance current it is DC power supply 1 →
Transistor Tr ₁ → resonance capacitor 6 → leakage inductance Ls → (rectifier 4, cable capacitance Ch and X-ray tube 5) → transistor Tr ₄ → flows through the circuit of DC power supply 1. During this period, the current i flowing through the first arm 2a
₁ and the current i ₄ flowing in the fourth arm 2d are as shown in FIG.
The waveforms are the same as shown in (f).

Next, at time Tb ₄ , the transistor Tr ₁ is turned off as shown in FIG.
As shown in, the transistor Tr ₂ is turned on. At this time, the resonance current it depends on the energy of the leakage inductance Ls, and the leakage inductance Ls → (rectifier 4, cable capacitance Ch and X-ray tube 5) → transistor Tr ₄
→ Diode D ₂ → Resonant capacitor 6 → Leakage inductance Ls flows through the circuit. Therefore, the second arm 2b negative current i ₂ flows as shown in FIG. 6 (g), a positive current i ₄ as shown in FIG. 6 (f) flows through the fourth arm 2d. Then, as the energy of the leakage inductance Ls decreases, the resonance current it approaches zero as shown in FIG. 6 (i).

Next, at time Tb ₅ , as shown in FIG. 6 (i), after the resonance current it becomes zero, the leakage inductance Ls → resonance capacitor 6 → transistor Tr ₄ → diode D ₄ → (rectifier 4, It flows through the circuit of the capacitance Ch of the cable and the X-ray tube 5), and increases in an arc of the resonance frequency determined by the leakage inductance Ls and the capacitance Cr of the resonance capacitor 6.

Next, at time Tb ₆ , the transistor Tr ₄ is turned off as shown in FIG. 6B, and at the same time, as shown in FIG.
As shown in, the transistor Tr ₃ is turned on. Then,
As shown in FIGS. 6C and 6D, the transistor Tr ₂ ,
Since both Tr ₃ are turned on, the resonance current it is the DC power supply 1 → transistor Tr ₃ → (rectifier 4, cable capacitance Ch and X-ray tube 5) → leakage inductance L.
s → resonance capacitor 6 → transistor Tr ₂ → DC power supply 1 circuit. During this period, the current i ₂ flowing through the second arm 2b and the current i ₃ flowing through the third arm 2c have the same waveform as shown in FIGS. 6 (g) and 6 (h).

Next, at time Tb ₇ , the transistor Tr ₂ is turned off as shown in FIG.
When the transistor Tr ₁ is turned on as shown in FIG.
The state is exactly the same as that from b _1, and the above operation is repeated thereafter.

In the case of controlling the operation phase of the inverter 2 as described above, the transistor Tr ₁ and the transistor Tr ₄ are turned on and off with the phase difference α, and the transistor Tr _{2 is} turned on.
And the transistor Tr ₃ are turned on and off with the phase difference α, the time (Tb _{3 to} Tb ₄ ) when the transistors Tr ₁ and Tr ₄ are turned on at the same time, and the transistor Tr 3
₂ and transistor Tr ₃ are on at the same time (Tb
_{6 to} Tb ₇ ) is shorter than the ON period of each switch by α. Then, power is supplied from the DC power supply 1 to the X-ray tube 5 only during this period. Therefore, the waveform of the output voltage vt of the inverter 2 is intermittent, as shown in FIG. 6 (j), in which the voltage of the DC power supply 1 has positive and negative peak values during the intermittent period, that is, the period of (180−α) °. It becomes a square wave. Therefore, by appropriately changing the phase difference α for turning on the transistors Tr ₁ and Tr ₄ and the phase difference α for turning on the transistors Tr ₂ and Tr ₃ , the respective transistors Tr _{1 to} Tr ₄ are turned on at the same time. It is possible to change the period for which the power is supplied and to control the power supplied to the X-ray tube 5. That is, the output power can be reduced by increasing the phase difference α, and when the phase difference α = 180 °, there is no period in which the transistors Tr _{1 to} Tr ₄ are simultaneously turned on, and the output power is reduced to zero. Can be dropped.

[0017]

In the above conventional device, the wiring between the DC power supply 1 and the inverter 2 actually has an inductance. That is, due to a steep current change at turn-on of the transistors Tr ₃ and Tr ₄ which delay the turn-on of the switch shown in FIG. A drop occurs (Ldi / dt), and the inverter 2
The voltages at b1 and b2, which are the input voltages of the
It causes a big depression like. Therefore, the output voltage of the inverter 2 has a waveform with a lacking rising edge with respect to the ideal square wave as shown in FIG. 6 (j), which also reduces the resonance current as shown by the dotted line in FIG. 6 (i). As a result, the tube voltage drops, pulsates, and fluctuates, resulting in a decrease in X-ray output and deterioration in radiation quality.

The object of the present invention is to reduce the drop of the input voltage of the inverter to suppress the fluctuation of the tube voltage and the drop of the output to improve the performance, and to reduce the size and weight of the entire apparatus and to cover a wide range from perspective to photographing. It is an object of the present invention to provide a resonant inverter X-ray tube high voltage device capable of controlling an output voltage with respect to a load.

[0019]

In order to achieve the above object, there is provided a first DC power source, a first switch connected to the positive electrode of the DC power source, and a second switch connected to the negative electrode. A series connection body and a second series connection body composed of third and fourth switches respectively provided in parallel with the first and second switches, and each of the first to fourth switches are antiparallel. An inverter having a connected diode and converting the output of the DC power supply into AC,
A high voltage transformer that boosts the output voltage of this inverter,
It has a rectifier for converting the output of this high-voltage transformer into a direct current and an X-ray tube connected to the output side of this rectifier, and has a leakage inductance of the high-voltage transformer or a series connection to this leakage inductance and leakage inductance. In an inverter type X-ray tube high voltage device using a connected capacitor as a resonance element, a signal for setting an X-ray condition radiated from the X-ray tube is used between a first switch and a fourth switch of the inverter, and a second switch. And a third switch for determining each operating phase, and the first and second switches of the inverter according to the output signal and the X-ray exposure signal from the phase determination circuit, and the third and third switches. A phase control circuit that alternately operates the fourth switch with a phase difference of 180 ° according to the operating frequency of the inverter, and an input that compensates for the drop in the input voltage of the inverter. Those having a pressure fluctuation suppression means.

[0020]

[Function] Between the first and fourth switches by the phase determination circuit,
And the phase difference between the second and third switches is determined, and the phase control circuit receives the output signal of this phase determination circuit and the X-ray exposure signal and the first and second switches, and the third and fourth switches. The switches are alternately operated with a phase difference of 180 ° to determine the output voltage. Further, the input voltage fluctuation suppressing means compensates for the voltage corresponding to the missing portion of the square wave caused by the voltage drop when the transistor is turned on.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention by a resonant inverter type X-ray high voltage device. The configuration and circuit operation of the main circuit section are the same as in FIG. In FIG. 1, the operating phases of the transistors Tr _{1 to} Tr ₄ of the inverter 2 are determined by setting signals of a voltage (hereinafter referred to as a tube voltage) and a current (hereinafter referred to as a tube current) to be applied to the X-ray tube 5. A phase determination circuit 9 is provided and
A signal for controlling the phase in which the transistors Tr _{1 to} Tr ₄ operate according to the output signal from the phase determination circuit 9 is
A phase control circuit 10 that outputs an X-ray exposure signal input from a controller (not shown) is provided. The signals from the phase control circuit 10 are supplied to the drive circuits 11a to 1a.
It is amplified by 1d and supplied to the bases of the transistors Tr ₁ to Tr ₄ to drive the inverter 2.

Next, each transistor Tr _{1 of the} inverter 2
~ The operation phase control of Tr ₄ will be described. First, when the tube voltage and the tube current to be supplied to the X-ray tube 5 as a load are determined, the tube voltage setting signal S ₁ corresponding to the tube voltage and the tube current setting signal S ₂ corresponding to the tube current are phased from the controller. Input to the decision circuit 9. Here, as shown in FIG. 8, the phase determination circuit 9 has a horizontal axis representing a phase difference α, a vertical axis representing a tube voltage V of the X-ray tube 5, and a relationship between the phase difference α and the tube voltage V being a load resistance value. _{R 1, R 2, R 3} , ... (R 1> R 2> R 3) and the like graduations were tabulated the graph representing a predetermined curve as a parameter or a function generator or an operational amplifier. Then, in the phase determination circuit 9, the load resistance values R ₁ and R _{1 are} calculated from the tube voltage setting signal S ₁ and the tube current setting signal S ₂ .
R ₂ , R ₃ , ... Are obtained, and the phase difference α and the tube voltage V in FIG.
Using the above relationship with the load resistance value, for example R _3, as a parameter, the intersection with the tube voltage V for which this curve is to be set is obtained, and each of the transistors Tr _{1 to} T of the inverter 2 is obtained.
Determine the phase difference α for the operation of r ₄ .

Then, the phase signal S corresponding to this phase difference α
₃ is output from the phase determination circuit 9 and the phase control circuit 10
To enter. In the phase control circuit 10, along with making the control signal the transistors Tr ₁ to Tr ₄ from the phase signal S ₃ is turned on, and turned off, the transistor Tr of the transistor Tr ₁ and the fourth switch as a first switch A control signal for controlling the phase difference α of _{4 and} the phase difference α of the transistor Tr ₂ as the second switch and the transistor Tr ₃ as the third switch is created. Then, when the X-ray exposure signal S ₄ is input to the phase control circuit 10 from the controller, the phase control circuit 10 sends the created control signal to each of the drive circuits 11a to 11d. Thus, the drive circuits 11a~11d, each transistor Tr ₁ of the inverter 2 in accordance with a control signal from the phase control circuit 10 to
Drive Tr ₄ .

FIG. 7 shows the operation waveform of each part at this time.
By the effect of the capacitor 7, the drop in the transistor Tr _3, the inverter input voltage that occurs when turn-on of the Tr ₄ towards delaying introduction of the switch is eliminated almost as shown in FIG. 7 (k). Therefore, the inverter output voltage also becomes a substantially square wave as shown in FIG. 7 (j), a resonance current flows, and a stable pulsation-free voltage as shown in FIG. 7 (i) is applied to the X-ray tube 5. be able to. At this time, the inverter 2 operates at or near the resonance frequency of the leakage inductance Ls of the transformer 3 and the capacitance Cr of the resonance capacitor 6.

FIG. 9 is a circuit diagram showing a second embodiment of the present invention. For simplification of description, parts having the same configurations and the same functions as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. This second embodiment is
A voltage divider 14 for detecting the tube voltage applied to the X-ray tube 5 is provided, and a detection signal from the voltage divider 14 and a preset target voltage signal (tube voltage setting signal S ₁ ) are input to determine the difference. An error amplification phase determination circuit 15 for amplifying and determining the operating phase of the transistor of the inverter 2 by this difference is provided. Further, the phase control circuit 10 is provided which outputs a signal for controlling the phase at which the transistor operates in accordance with the output signal from the error amplification phase determination circuit 15 and the X-ray exposure signal S ₄ input from the controller. .. Reference numeral 16 is a signal conversion circuit that converts the signal detected by the voltage divider 14 into a signal suitable for use in the error amplification phase determination circuit 15.

By the voltage divider 14, the error amplification phase determination circuit 15 and the phase control circuit 10, the transistor Tr ₁ as the first switch and the transistor Tr ₂ as the second switch of the inverter ₂ are connected to the inverter. The transistor Tr ₃ as the third switch and the transistor Tr ₄ as the fourth switch are alternately turned on at the operating frequency of 2, and the first transistor Tr ₁ and the fourth transistor Tr ₄ are alternately turned on. By appropriately changing the phase difference of _{4 and} the phase difference of the second transistor Tr ₂ and the third transistor Tr ₃ , the power supplied to the X-ray tube 5 is feedback-controlled.

Next, the operation of the second embodiment constructed as above will be described. First, when the tube voltage supplied to the X-ray tube 5 is determined, the tube voltage setting signal S ₁ corresponding to this tube voltage is input from the controller to the error amplification phase determination circuit 15 as a target voltage signal. On the other hand, the error amplification phase determination circuit 15 includes a signal conversion circuit 16 which is detected by the voltage divider 14.
Tube voltage detection signal S corresponding to the current tube voltage converted by
₅ is entered. Then, this error amplification phase determination circuit 1
Reference numeral ₅ detects an error between the tube voltage setting signal S ₁ and the tube voltage detection signal S _5, and the inverter 2 corresponds to the magnitude of this error.
The phase difference α of the operation of each of the transistors Tr _{1 to} Tr ₄ is determined. A phase signal S ₃ corresponding to the phase difference α is output from the error amplification phase determination circuit 15 and input to the phase control circuit 10. At this time, since the tube voltage detection signal S ₅ is zero with respect to the tube voltage setting signal S ₁ before the start of X-ray irradiation, the phase difference α is set to zero so that maximum power can be supplied.

Next, in the phase control circuit 10, a control signal for turning on and off each of the transistors Tr _{1 to} Tr ₄ is generated from the phase signal S ₃ and at the same time, the transistor Tr ₁ as the first switch and the fourth transistor Tr ₁ are turned off. A control signal for controlling the phase difference α of the transistor Tr ₄ as a switch and the phase difference α of the transistor Tr ₂ as the second switch and the transistor Tr ₃ as the third switch is created. Then, when the X-ray exposure signal S ₄ is input to the phase control circuit 10 from the controller, the phase control circuit 10 sends the created control signal to each of the drive circuits 11a to 11d. As a result, each of the drive circuits 11a to 11d causes each of the transistors T of the inverter 2 to follow the control signal from the phase control circuit 10.
Drive r _{1 to} Tr ₄ .

In this way, the transistors Tr ₁
When Tr ₄ starts to operate, a resonance current it as shown in FIG. 7 flows in the transformer 3, a tube voltage starts to be applied to the X-ray tube 5, and a tube current flows. When the tube voltage of the X-ray tube 5 approaches the set value, the error between the tube voltage setting signal S ₁ and the tube voltage detection signal S ₅ becomes small. It operates so as to increase the phase difference α and reduces the power supply from the DC power supply 1. X
When the tube voltage of the wire tube 5 becomes substantially equal to the set value, the inverter 2 operates in a phase in which the DC power source 1 can supply electric power equal to the electric power due to the set tube voltage and tube current. At this time, the inverter 2 operates at or near the resonance frequency of the leakage inductance Ls of the transformer 3 and the electrostatic capacity Cr of the resonance capacitor 6.

FIG. 10 is a circuit diagram showing a third embodiment. In this embodiment, the DC power supply 1 is obtained by receiving an AC from a commercial power supply, rectifying it into a DC and smoothing it. In FIG. 10, 17 is a rectifier for full-wave rectifying the received commercial power source, and four diodes D ₉ to
It consists of D ₁₂ . L'is an inductance and C'is a capacitance, and the output of the rectifier 17 is smoothed by the inductance L'and the capacitance C '. In the case of this embodiment, the output power can be increased as compared with the embodiment shown in FIG.
For example, electric power of about several tens to 100 kW can be supplied. The control range can be further widened by replacing the rectifier 17 with a thyristor and varying the input voltage of the inverter 2.

In the embodiment of FIGS. 1, 9 and 10, when the heat generation of the capacitor 7 as the input voltage fluctuation suppressing means poses a problem, as shown in FIG.
And a resistor 8 connected in series. When the temperature of the capacitor 7 gradually rises, its impedance decreases, and when this frequency, which is the minimum at a certain frequency, is close to the inverter frequency, the current flowing through the capacitor 7 increases, and the temperature further rises, causing thermal runaway. Therefore, the resistance value of the resistor 8 may be selected to be the minimum value for ensuring an arbitrary impedance at this frequency. Furthermore, since the output power is small during long-time exposure such as through fluoroscopy, the drop in the inverter input voltage due to transistor switching is small and the capacitor 7 is not required. Therefore, as shown in FIG. Disconnect from the circuit. Although a transistor is used as a switching element of the inverter 2, the present invention is not limited to these examples, and for example, GTO can be used.
To further increase the frequency, MOSFET, IGBT, S
It is also possible to use an I transistor, an SI thyristor, or the like. Further, the load is not limited to the X-ray tube 5, but can be similarly applied as long as the load requires a relatively high voltage DC output. Further, the error amplification phase determination circuit 15 shown in FIGS. 9 and 10 is generally based on proportional-integral control, but the present invention is not limited to this, and once the digital value is exchanged, software control is applied. You may.

[0032]

According to the present invention, the transistor T of the inverter is used.
By switching r _{1 to} Tr _4, the drop of the inverter input voltage due to the voltage drop that occurs in the inductance of the wiring between the DC power supply and the inverter is made smaller by the capacitor or the series connection of the capacitor and the resistor, so there is no pulsation or fluctuation. The tube voltage can be obtained. Also, if the frequency is raised, the heat generation of the capacitor immediately before the inverter becomes a problem, but this can be suppressed by the resistor connected in series with this capacitor, and this capacitor can be suppressed during long-term exposure such as fluoroscopy. Can be solved by disconnecting from the circuit. Therefore, by increasing the frequency of the inverter according to the present invention, the entire apparatus can be made smaller and lighter, and the output voltage for a wide range of loads from fluoroscopy to photography can be controlled stably.

[Brief description of drawings]

FIG. 1 is a circuit diagram in which a capacitor is used as an input voltage fluctuation suppressing means of an inverter type X-ray high voltage device according to the present invention.

FIG. 2 is a main circuit diagram of FIG.

FIG. 3 is a main circuit diagram in which a series connection body of a capacitor and a resistor is used for the input voltage fluctuation suppressing means of FIG.

FIG. 4 is a main circuit diagram in which a contact is added to the input voltage fluctuation suppressing means of FIG.

FIG. 5: Conventional main circuit diagram

FIG. 6 is an operation waveform diagram of each part of the conventional device in FIG.

7 is an operation waveform diagram of each part of the device of the present invention in FIG.

FIG. 8 is a graph showing the relationship between the phase difference and the tube voltage in the phase determination circuit by using the load resistance as a parameter.

FIG. 9 is a circuit diagram showing a second embodiment.

FIG. 10 is a circuit diagram showing a third embodiment.

[Explanation of symbols]

 1 DC power supply 2 Inverter 3 Transformer 4 Rectifier 5 X-ray tube 6 Resonant capacitor 7 Capacitor 8 Resistance 9 Phase determination circuit 10 Phase control circuit 11 Drive circuit 12 Contact 14 Voltage divider 15 Error amplification phase determination circuit 17 Rectifier it Resonant current Tr transistor D Diode Ls Leakage inductance L'Inductance Cr Resonance capacitor capacitance Cs Stray capacitance Ch Cable capacitance C'Capacitance

Claims (1)

[Claims] 1. A first series connection body comprising a DC power supply, a first switch connected to the positive electrode of the DC power supply, and a second switch connected to the negative electrode, and the first and second switches. And a second series connection body composed of a third and a fourth switch, which are respectively provided in parallel with each other, and a diode that is respectively connected in antiparallel to the first to fourth switches, and the output of the DC power supply To an AC, a high-voltage transformer that boosts the output voltage of this inverter, a rectifier that converts the output of this high-voltage transformer to a DC, and an X-ray tube connected to the output side of this rectifier. And a leakage inductance of the high-voltage transformer or an inverter type X-ray tube high-voltage device using the leakage inductance and a capacitor connected in series to the leakage inductance as a resonance element. A phase determination circuit that determines each operating phase between the first and fourth switches and between the second and third switches of the inverter by a signal that sets the X-ray condition emitted from the X-ray tube, and this phase. According to the output signal from the decision circuit and the X-ray exposure signal, the first and second switches, and the third and fourth switches of the inverter are respectively adjusted to the operating frequency of the inverter with a phase difference of 180 °. An inverter type X-ray high voltage device comprising: a phase control circuit that operates alternately and an input voltage fluctuation suppressing means that compensates for a drop in the input voltage of the inverter.