JPS5926120B2 - X-ray generation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray generation circuit, and more particularly to a tube voltage adjustment circuit for an X-ray tube.

Conventional x-ray generating circuits use an auto-turn sliding transformer or other transformer provided at the input stage of a high-voltage transformer to adjust the tube voltage of the x-ray tube.

Therefore, when a device is constructed by incorporating such a circuit, the device becomes large and heavy, which has the disadvantage that it is particularly unsuitable as a portable device.

The present invention eliminates these drawbacks, and makes it possible to adjust the tube voltage without using a transformer, making the device smaller and lighter when incorporated into the device, and making it suitable for portable X-ray devices. The purpose is to provide a generation circuit.

An embodiment of the present invention will be described below with reference to FIG.

Reference numeral 1 denotes a commercial frequency AC power supply, and a rectifier circuit 4 in which diodes 2, 2 and thyristors 3, 3 are bridge-connected is connected to both ends of the AC power supply.

A series circuit of a coil 5 and a capacitor 6 is connected between the oppositely connected ends of the rectifier circuit 4.

A primary winding of a high voltage transformer 8 is connected to both ends of this capacitor 60 via a switching element 7 .

This switching element 7 is connected to an oscillation circuit 10.

Further, the X-ray tube 11 is connected to the secondary winding of the high-voltage transformer 80, and 12 is a filament transformer of the X-ray tube 11.

13 is the tertiary winding of the high voltage transformer 8; this tertiary winding 1
3) is connected to a series circuit of a diode 14 and a capacitor 15.

Both ends of this capacitor 140 are connected to a resistor 16 connected in parallel.
It is connected to the differential amplifier 17 via.

A variable reference power source 18 connected between the amplifier 17 and the resistor 16 is connected to the amplifier 17 .

Further, this amplifier 17 is connected to the thyristors 3, 3.

Next, the operation of one embodiment configured as described above will be explained.

The alternating current voltage of the commercial power source 1 is rectified and phase-controlled by a rectifier circuit 4, and is charged to a capacitor 6 through a coil 5.

This charging voltage is converted into a pulsed voltage by switching the switching element 7 at a desired frequency.

Then, this pulse voltage is applied to the primary winding of the high-voltage transformer 80, and the voltage generated in the secondary winding is applied to the X-ray tube 11 as an X-ray tube voltage to generate X-rays.

By the way, a voltage proportional to the X-ray tube voltage is generated in the tertiary winding 13.

This voltage is then applied to the diode 14 and capacitor 15.
and a voltage proportional to the peak value of the voltage, that is, the peak value of the X-ray tube voltage, is detected.

This voltage is compared with a reference voltage 18 by a differential amplifier 17, and the difference signal is negatively fed back to the thyristors 3, 3.

Therefore, the phases of the thyristors 3 and 30 are controlled to always keep the peak value of the X-ray tube voltage constant.

Note that by changing the voltage value of the reference voltage 18,
Tube voltage settings can be easily changed.

With this configuration, the tube voltage can be controlled to be constant.

Incidentally, as shown in FIG. 2, a circuit for detecting a voltage proportional to the tube voltage may be provided on the transformer 8 side of the capacitor 6.

That is, dividing resistor 2 connected in parallel to capacitor 6
1.22 and a capacitor 23 connected in parallel to one of the resistors 22, a voltage proportional to the peak value of the primary voltage of the high voltage transformer 80, that is, the peak value of the tube voltage is detected, and this detected value is and the reference voltage 18, and the phase of the thyristors 3, 3 is controlled by the difference signal.
(Also good.

Still, as shown in FIG. 3, the rectifier circuit 4 is connected to a diode 2.
2. 2', 2' and after direct rectification,
The switching element 30 connected in series with the coil 5 and capacitor 6 switches the voltage at several kHz, charges and smoothes the capacitor 6 through the coil 5, and switches this voltage at several hundred Hz using the switching element 7 to supply the primary voltage of the high voltage transformer 8. It may also be supplied to the winding.

In this case, the voltage proportional to the tube voltage is detected using a voltage detection circuit shown in FIG.
By controlling the ratio, the peak value of the tube voltage can be made constant.

Furthermore, as shown in FIG. 4, the same implementation is possible using the voltage detection circuit shown in FIG. 2.

As shown in Fig. 5, the voltage detection circuit directly detects the tube voltage using a dividing resistor 51.52° and a capacitor 53 connected to the secondary winding side of the transformer 80, and compares it with the reference voltage 18. 3°3 may also be phase controlled.

Note that transistors 54 and 54 are used as switching elements.
The transistors 54 and 54 are alternately switched to excite the primary winding of the transformer 8 and generate an alternating current voltage in the secondary winding, and this alternating voltage is converted to a direct current voltage by the rectifier circuit 55. It may also be applied to the X-ray tube 11.

Since the present invention is configured in this way, not only can the peak value of the tube voltage be kept constant, but there is no need to use a single-turn sliding transformer or the like to set the X-ray tube voltage as in the conventional case. Particularly, when incorporated into a portable X-ray generator, it is possible to obtain a small, lightweight, and easy-to-handle device.

[Brief explanation of the drawing]

The drawings are for explaining the present invention; FIG. 1 is a circuit diagram showing one embodiment of the invention, and FIGS. 2 to 5 are circuit diagrams showing other embodiments. In the figure, 1 is a commercial power source, 2. 2. 2', 2' are diodes, 3, 3 are thyristors, 4, 55 are rectifier circuits,
7.30, 54, 54 are switching elements, 8 is a high-voltage transformer, 11 is an X-ray tube, 13 is a tertiary winding, 14.15 is a diode and capacitor for detecting peak voltage, 17
is a differential amplifier, 18 is a variable reference voltage, 21, 22, 51
, 52 are dividing resistors.

Claims (1)

[Claims] 1. An AC power source, a rectifier circuit connected to the power source, a high-voltage transformer connected to the rectifier circuit, and a switching device connected between the secondary winding of the transformer and the rectifier circuit. and an X-ray tube connected to a secondary winding of the transformer, the voltage detection circuit detecting a tube voltage of the X-ray tube or a voltage proportional to the tube voltage; An X-ray generation circuit comprising: a comparison circuit that compares the output voltage of the circuit with a reference voltage; and a feedback circuit that feeds back the output of the circuit between the rectification circuit and the switching circuit. 2. X according to claim 1, characterized in that the feedback circuit is connected between the comparator circuit and the gate of a thyristor which constitutes the rectifier circuit with a diode.
Line generation circuit. 3. The X-ray generating circuit according to claim 1, characterized in that the feedback circuit is connected between the rectifier circuit, another switching circuit inserted between the switching circuits, and the comparator circuit. . 4. Any one of claims 1 to 3, wherein the voltage detection circuit is configured to detect a voltage proportional to the tube voltage excited in the tertiary winding of the high-voltage transformer. X-ray generation circuit described in section. . 5. Any one of claims 1 to 3, wherein the voltage detection circuit is configured to detect a voltage proportional to the tube voltage on the primary side of the high voltage transformer.
X-ray generation circuit described in section. 6. The X-ray generator according to any one of claims 1 to 3, wherein the voltage detection circuit is configured to directly detect the tube voltage from the secondary side of the high-voltage transformer. circuit. 7. The X-ray generation circuit according to any one of claims 1 to 3, characterized in that the reference voltage is variable.