JPS62278798A - X-ray generator - Google Patents

Abstract

PURPOSE:To decrease the effect of impulse noise on a controller even when abnormal discharge is generated on load side by arranging inductances which suppress quick current variation caused by abnormal discharge on load side in high voltage generating circuit of the secondary side of a step-up transformer. CONSTITUTION:When abnormal discharge is generated on a load side, for example, by damage of high voltage cable connected to an X-ray tube 9, between the cable and the ground, impedance of the X-ray tube 9 is rapidly decreased and current supplied to the X-ray tube 9 tends to quickly increse. The current supplied to the X-ray tube 9 is suppressed by inductances 10, 11 arranged on output side of rectifiers 3, 4. Since impulse noise produced when abnormal discharge is generated on load side is mainly caused by current variation, this impulse is also decreased.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention is designed to suppress the rapid increase in A current due to abnormal rli current on the load side. This invention relates to an X-ray generator.

(Conventional technique t1.i) A conventional continuous X-ray generator, as shown in FIG. The secondary side output of each is full-wave rectified to create a positive voltage.

Rectifiers 3 and 4 that obtain negative voltage, capacitor 5.6 that smoothes the DC output of these rectifiers 3.4, and the positive voltage obtained by rectifier 3, and the negative voltage obtained by rectifier 4. Xs where rrH is applied to the filament via protective resistors 7 and 8, respectively
It consists of a high pressure generation circuit equipped with a pipe 9. In this case, the neutral pole of the X-ray tube 9 is connected to the ground circuit of the capacitor 5.6.

However, in such an Xaa generation device, if abnormal discharge occurs on the load side due to deterioration or failure of the X-ray tube 9 or damage to the high-voltage cable, the current flowing through the high-voltage generation circuit will change rapidly, and the degree of the change will be particularly It becomes larger due to the smoothing capacitor 5.6.

Normally, the XrA tube CH;CO,! It has an impedance of 2 MΩ to several MΩ, but if the impedance suddenly becomes low due to an abnormality in the X-ray tube 9, the current flowing into the X-ray tube 9 also rises rapidly, and this becomes impulse noise.

Therefore, in such an xi generator, if impulse noise occurs due to an abnormality in the X-ray tube, for example, as described above, this impulse noise will share not only the control section (not shown in FIG. 4) but also the ground circuit. It also has a serious impact on other equipment.

Particularly, in the case of a recent XM device in which a high frequency and a semiconductor are used for the striking part in order to achieve miniaturization, the element may be destroyed by impulse noise. Furthermore, when a system such as a CT device is connected to other devices to construct M4, the effect may even affect the entire CRAM.

(Problem to be solved by the invention) As described above, in the conventional XM generator, when abnormal discharge occurs on the load side due to deterioration or failure of the There is a problem in that impulse noise caused by changes in current affects other devices through the control section and common ground circuit, leading to destruction of devices, especially in parts that use semiconductor circuits.

Therefore, an object of the present invention is to reduce the influence of impulse noise on the control unit and other devices connected through the common ground circuit even if abnormal discharge occurs on the load side. 1 to provide generated VitrIl.

(Means for Solving the Problems of the Invention) In order to achieve the above objects, the present invention provides an AC m1l
In the X-ray generator, the output voltage of 1 is boosted by a 4-voltage transformer, and the secondary output thereof is rectified by a rectifier, and a DC voltage is applied to the X-ray tube to generate XI1, wherein the step-up transformer It is characterized by the provision of an inductance in the high voltage generation circuit on the secondary side to suppress sudden changes in current due to abnormal discharge on the load side.

(Function) Therefore, in the Xts generator H having such a configuration, even if an abnormal discharge 1 occurs on the load side, for example, an abnormal discharge inside the X-ray tube or a discharge from a high-voltage cable to the ground, the abnormality flowing at this time will occur. The rate of increase in N flow is If! due to inductance. Since the impulse noise is reduced, it is possible to reduce the influence on the control unit and other devices connected through the common ground circuit.

(Example) An example of an IM according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the circuit configuration of an X-ray generator according to the present invention, and the same parts as in FIG. 4 are shown with the same symbols. In Fig. 1, 1 is an AC power supply, and the output voltage of this AC power supply 1 is the tube voltage, tube voltage? ! ! It is input to a not-shown ♂ 1111O unit which controls the flow rate and firing time based on respective set values. 2 is a primary winding 2a that boosts the output voltage obtained from this control part 1, and two secondary windings 9JPJ2b, 2.
One secondary winding 2b of the step-up transformer 2 is connected to the input terminal of the rectifier 3, and the other secondary winding 2C is connected to the input terminal of the rectifier 4.

The rectifier 3 performs full-wave rectification of the output voltage of one secondary reference line 2b to obtain a positive voltage, and connects one output terminal of the rectifier 3 with an inductance of 10. The anode of the X-ray tube 9 is connected to the anode of the X-ray tube 9 through the resistor 7 in series. Moreover, the rectifier 4 is connected to the other secondary winding I! 12c is full-wave rectified to obtain a negative voltage, and one output terminal of this rectifier 4 is connected to an inductance 11. A protective resistor 8 is connected in series to the filament of the X5il tube 9. The other output terminals of both rectifiers 3.4 are connected to Ffi through a resistor 12.13.
Then, it is connected to the neutral pole of the X-ray tube 9 and grounded. Furthermore, smoothing capacitors 5 and 6 are connected between the output terminals of the rectifier 3.4.

In an X-ray generator with such a configuration, if an abnormal discharge occurs between the load side 1, for example, the high-voltage cable connected to the X-ray tube 9, and the ground, the impedance of the XIl9 suddenly decreases to a low impedance. Therefore, the current flowing into the X-ray tube 9 also tends to rise rapidly. However, the current flowing into this X-ray tube 9 is
It is suppressed by the inductance 11.12 provided on the output side of .

Here, we will consider the equidistant circuit when only the protective resistor R (7, 8) is provided in the high voltage generation circuit and when the protective resistor R (7, 8) and inductance L (10, 11) are provided. The current waveform 1 flowing through the high voltage generation circuit due to abnormal discharge on the load side is shown in Fig. 2 (a) and Fig. 3 (a), respectively.
are shown in FIG. 2(b) and FIG. 3(b), respectively. This figure 2(a).

As is clear from (b) and Figures 3 (a) and (b), the current change is large when only the protective resistor R and inductance L are provided, whereas the current change is large when only the protective resistor R and inductance L are provided. It can be seen that when the inductance is set, the current rises slowly due to the inductance, and current changes are suppressed. Since the impulse noise generated when abnormal discharge occurs on the load side is largely due to current changes, this impulse noise is also reduced.

Therefore, even if an abnormal discharge occurs on the load side due to deterioration or failure of the X'm tube, damage to the high voltage cable, etc., impulse noise can be reduced by suppressing current changes, so it can be applied to other devices through the control unit and common ground circuit. The influence can be reduced, and the elements will not be destroyed, especially in areas where semiconductor circuits are used. Also, slowing down the current change means that the rate of increase in abnormal current will be slow.
If the high voltage generation circuit is equipped with an abnormality detection section and a protection circuit, the protection function can be fully demonstrated even in the case of a time delay between the detection of an abnormality in the abnormality detection section and the activation of the protection circuit. becomes more sexual.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

[Effects of the Invention] As described above, according to the present invention, the output voltage of an AC power supply is boosted by a step-up transformer, and the secondary output is rectified by a rectifier, and the DC voltage obtained is applied to the XIA tube.
In the X-ray generator that generates $I, the high voltage generation circuit on the secondary side of the step-up transformer is provided with an inductance that suppresses sudden changes in current due to abnormal discharge on the load side. Discharge 2 e.g. X$I
11i from abnormal discharge inside the pipe or high voltage cable etc. to the ground
Even if electricity is generated, the impulse noise generated at that time is reduced, and it is possible to provide an XWA generator that can reduce the influence on the control unit and other devices connected through the common ground circuit.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the X-ray generator according to the present invention, FIGS. 2(a), (b) and 3(a),
(b) is a diagram showing a comparison of the equivalent circuit and its current waveform when only a protective resistor is provided in the high voltage generation circuit and when a protective resistor and inductance are provided in the high voltage generating circuit in the same embodiment, respectively. is a circuit configuration diagram showing a conventional xmm generation wage. 1... AC power supply, 2... Promotional transformer, 3.4... Rectifier, 5, 6... Capacitor, 7.8...・Protective resistance, 9...
X-ray tube, 10.11...Inductance, 12
．． 13...Resistance. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (1)

[Claims] In the X-ray generator, the output voltage of an AC power source is boosted by a step-up transformer, and the secondary side output thereof is rectified by a rectifier, and the resulting DC voltage is applied to the X-ray tube to generate X-rays. An X-ray generator characterized in that an inductance is provided in a high voltage generation circuit on the secondary side of a transformer to suppress sudden changes in current due to abnormal discharge on the load side.