JPH0428200A - Power source device of x-ray generator - Google Patents

Abstract

PURPOSE:To perfectly remove a pulsating component from source power so as to obtain stable-level X-rays by converting the source power into its corresponding power through a process of switching control. CONSTITUTION:When any desired tube voltage value and any desired tube current value are respectively set to a tube voltage/tube current setter circuit 16, a suitable drive pulse signal is impressed on each of thyristors and transistors so that a desired tube voltage and a desired tube current are given respectively to a filament 6 and a target 7. In this case, a DC-DC converter 8 is arranged between a rectifier circuit 2 and each of inverters 3, 13, and then a pulsating component, corresponding to power cycle, included in an output signal from the rectifier circuit 2 is removed by the switching action of a transistor TR1 in the converter 8 and the smoothing action of a smoothing circuit 21 in the converter 8. Thus a power source device can always supply stable-level power to an X-ray generator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply device for driving an X-ray generator.

[Prior Art] An X-ray generator generally has a filament and a target placed opposite the filament. A high DC voltage is applied between the filament and the target. Furthermore, by passing a current through the filament, the filament is heated to a high temperature and electrons are emitted from it.

The emitted electrons are accelerated by a direct current high voltage and collide with a target placed opposite the filament, from which X-rays are emitted.

2. Description of the Related Art Conventionally, a device shown in FIG. 2 has been known as a power source for supplying power to a filament and a target.

In this device, an AC voltage supplied from a commercial power supply 1 is rectified by a rectifier circuit 2 and converted into a DC voltage, and the DC voltage is converted to an AC voltage by an inverter 3.
Furthermore, the voltage is boosted by a high voltage generator 4 having a built-in step-up transformer, etc., and then the high voltage is transferred to a rectifier circuit 5.
The current is applied between the filament 6 and the target 7 after rectification.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional device, the electric power [
The pulsation corresponding to the period of 1 remains, therefore, target 7
There was a problem that the X-rays emitted from the

Furthermore, when the current flowing from the filament 6, the so-called tube current, is increased, a voltage drop occurs in the voltage applied between the filament 6 and the target 7, the so-called tube voltage, making the tube voltage unstable. There was also the problem.

The present invention has been made in view of the above-mentioned problems in conventional devices, and an object of the present invention is to provide a power supply device that can constantly supply stable power without pulsation to an X-ray generator.

[Means for Solving the Problem] In order to achieve the above object, the power supply device according to the present invention has the following features:
A DC-DC converter with a built-in switching element is disposed between a rectifier for rectifying the power supply voltage and an inverter for converting the rectified voltage into alternating current, and the voltage output from the rectifier is It is characterized in that it is supplied to the inverter after conducting conduction control using a switching element.

Generally, the switching element operates ON10FF based on a drive signal such as a pulse signal. In the present invention, the DC-DC converter may be provided with a feedback loop for feeding back the output signal of the DC-DC converter to its drive signal.

[Operation] Power conversion is performed on the voltage output from the rectifier (2) by the switching operation of the switching element (transistor TRI) provided in the DC-DC converter (8). At the same time, the pulsations in the power cycle included in the DC voltage are removed.

The output of the DC-DC converter is connected to a switching element (T
switching drive means (PWM
Circuit 17. By providing feedback to the drive circuit 18), even if the current flowing in the X-ray tube in the X-ray generator (33), that is, the tube current, fluctuates,
The power supplied to the X-ray generator can always be kept constant.

[Embodiment] FIG. 1 is a circuit diagram showing an embodiment of a power supply device according to the present invention. This power supply device supplies power to an X-ray generator 33 having a filament 6 and a target 7.

In this embodiment, a commercial power source 1, for example, AC200
The voltage supplied from V is rectified by the rectifier circuit 2 and converted into direct current, and then the DC-DC converter 8 stabilizes the direct current voltage.

The output of the DC-DC converter 8 is divided into two parts, one of which is converted into alternating current by a full-bridge type tube voltage inverter 3, then boosted by a step-up transformer 9, and further rectified by a rectifier 1o. 80
A voltage of Kv is applied between the filament 6 and the target 7.

On the other hand, the output of the DC-DC converter 8 is converted into alternating current by a half-bridge type (of course, a full-bridge type is also acceptable) tube current inverter 13,
Then, the voltage is stepped down by the transformer 19, and then the rectifier 2
After being rectified by o, it is fed into the filament 6. As a result, the filament 6 generates heat and electrons are emitted from it.

The emitted electrons are accelerated by the potential difference between the filament 6 and the target 7 and collide with the target 7,
X-rays are emitted from it. The emitted X-rays are used as an X-ray source in an X-ray diffraction device and other various X-ray instruments. As for these X-ray devices, well-known ones can be used as they are, so
Detailed explanation will be omitted.

In this embodiment, the rectifier circuit 2 includes two diodes D
I, D2 and two thyristors THI.

Bridge 11 constituted by TR2 and coil L1
Smoothing circuit 12 composed of capacitor CI and capacitor CI
and a voltage dividing circuit 14 configured by two resistors R1 and R2 connected in series. Bridge 1
The number of thyristors constituting one may also be four.

Thyristors THI and TH2 in the bridge 11 are both driven by a drive circuit 15 that operates based on commands from a tube voltage/tube current setting circuit 16, and are turned ON10.
FF works. The voltage rectified by this 0N10FF operation is smoothed by the smoothing circuit 12 and then D
The signal is sent to the C-DC converter 8. At this time, the output signal is taken out as a voltage signal by the voltage dividing circuit 14 and fed back to the input terminal of the drive circuit 15.

The DC-DC converter 8 is a tube voltage/tube current setting circuit 1
0N10F by the PWM (pulse width modulation) circuit 17 and drive circuit 18 that operate based on commands from 6
It has an F-driven transistor TRI, a smoothing circuit 21 made up of a coil L2 and a capacitor C2, and a voltage dividing circuit 22 made up of two resistors R3 and R4 connected in series.

The voltage input to the DC-DC converter 8 is converted into a pulsed alternating current by the 0N10FF operation of the transistor TRI, and is further smoothed by the smoothing circuit 21 to be converted into power. The current is sent to the tube current inverter 13.

The tube voltage inverter 3 includes four transistors TR2~
It is formed by a bridge 23 (so-called full bridge) made up of TR5. The gates G2 to G5 of each of these transistors TR2 to TR5 are PWM
It is connected via a circuit 24 to a drive circuit 25 that operates based on commands from the tube voltage/tube current setting circuit 16.

The tube current inverter 13 includes two capacitors C2 and C.
3 and two transistors TR6 and TR7 (so-called half bridge).

The gate G of each of these transistors TR6 and TR7
6 and G7 are connected via a PWM circuit 27 to a drive circuit 28 that operates based on commands from the tube voltage/tube current setting circuit 16.

In the power supply circuit from the rectifier 10 for supplying tube voltage to the X-ray generator 33, two resistors R5 and R are connected in series.
A voltage dividing circuit 29 constituted by 6 is provided.

Fluctuations in the tube voltage applied between the filament 6 and the target 7 are detected by this voltage dividing circuit 29, and the fluctuating signal is sent to the P for tube voltage control via the electrical insulation means 30.
It is fed back to the input terminal of the WM circuit 24.

Further, a current detection circuit 31 is connected to the power supply circuit, and this current detection circuit 31 detects fluctuations in the current flowing in the power supply circuit, that is, the tube current. This current fluctuation is fed back to the input end of the PWM circuit 27 for tube current control via the electrical insulation means 32.

The tube voltage/tube current setting circuit 16 includes thyristors TH1, TH2, DC-
Transistor TRI in DC converter 8, transistors TR2 to TR5 forming full bridge 23, and transistors TR6 and T forming half bridge 26.
Data regarding how each element of R7 should be driven is stored. Therefore, by setting any desired values of tube voltage and tube current in this tube voltage/tube current setting circuit 16, appropriate drive pulse signals are applied to each of the above-mentioned thyristors and transistors, and as a result, the filament 6 A desired tube voltage and tube current are applied to the target 7.

In this case, in this embodiment, a DC-DC converter 8 is provided between the rectifier circuit 2 and the inverters 3 and 13, and the switching operation by the transistor TRI and the smoothing action by the smoothing circuit 21 in the converter 8 cause rectification. The pulsating component corresponding to the power cycle included in the 8-power signal from the circuit 2 is removed. In addition, the output signal of the DC-DC converter 8 is
2 and fed back to the gate input side of the transistor TRI. Therefore, when a fluctuation occurs in the tube current, the ON/FF timing of the transistor TRI is controlled to correct the fluctuation. This makes it possible to always provide stable power supply.

In this embodiment, the rectifier circuit 2, the tube voltage control full bridge 23, and the tube current control half bridge 26 are each provided with a feedback loop, so stable power with very little fluctuation is supplied to the X-ray generator. 33 can be supplied.

In this embodiment, a feedback loop to the tube voltage control PWM circuit 24 and a tube current control PWM circuit 2 are provided.
Electrical insulating means 30 and 32 are arranged in each of the feedback loops to the X-ray generator Wt.
Even if an abnormal situation such as discharge occurs in the transistor 33, it is possible to prevent an accident in which an abnormal current flows to the transistor drive system. In this case, the electrical insulation means 30.32 may include a photocoupler that converts an electrical signal into an optical signal and transmits it, a signal transmission system that converts the electrical signal to V/F (voltage/frequency) and transmits it through an optical fiber, Or something like a so-called isolation amplifier. An electrically insulated signal transmission system is used.

Although the present invention has been described above using one example, the present invention is not limited to that example.

In the above embodiment, the transistor TR1 is used as the switching element built into the DC-DC converter 8, but any switching element other than the transistor or a switching circuit that performs the same function may also be used. Furthermore, various devices such as smoothing circuits associated with the switching elements and the like can be selected and used as desired.

The rectifier circuit 2, the tube voltage inverter 3, and the tube current inverter 13 are not limited to the circuit configuration shown in the figure, but may have any other circuit configuration that performs the same function.

[Effects of the Invention] According to the present invention, a DC-DC converter is arranged in a power supply path leading from a power source to an X-ray generator, and power is converted from power source by controlling switching of a switching element provided in the converter. Since the power is supplied to the X-ray generator in a state where the pulsating component of the power cycle is completely removed, power is supplied to the X-ray generator. Therefore, X
The ray generator produces stable X-rays without pulsation.

Furthermore, if the output of the DC-DC converter is fed back to the driving means for driving the switching element, even if the tube current fluctuates, the power supplied to the X-ray generator can be maintained at a constant level. can be held.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a power supply device according to the present invention, and FIG. 2 is a circuit diagram showing an example of a conventional power supply device. DESCRIPTION OF SYMBOLS 1... Commercial power supply, 2... Rectifier circuit, 3... Tube voltage inverter, 6... Filament, 7... Target, 8-... DC-DC converter, 9... Step-up transformer , 13... Tube current inverter, 17...P
WM circuit, 18...drive circuit, 33...X-ray generator, TRI...transistor

Claims (2)

[Claims] (1) AC voltage is rectified by a rectifier and converted to DC voltage, the DC voltage is converted to AC voltage by an inverter and then boosted, and the boosted voltage is rectified and applied between the filament and the target. In a power supply device for an X-ray generator, a DC-DC converter with a built-in switching element is disposed between the rectifying means and the inverter, and the voltage output from the rectifying means is controlled by the switching element. A power supply device characterized in that the power supply device is supplied to an inverter after conduction control is performed. (2) In the power supply device according to claim 1, the DC-DC converter has a feedback loop, and the output signal of the DC-DC converter is a switching drive for driving the switching element by the feedback loop. A power supply device characterized by being returned to a means.