JP3053122B2 - X-ray high voltage equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray high voltage device, and more particularly to an X-ray high voltage device provided with a capacitor for applying a charging voltage to an X-ray tube.

[0002]

2. Description of the Related Art In this type of X-ray high-voltage device, a voltage from a commercial power supply is boosted by a transformer, an output from the transformer is charged by a capacitor, and a charged voltage of the capacitor is applied to an X-ray tube. It is supposed to.

Then, in order to keep the charging voltage of the capacitor almost constant, the detected voltage is taken out from the X-ray tube side, and when the taken out voltage reaches a preset voltage, the transformer of the commercial power supply is used. Charge control means for interrupting supply to the transformer and supplying the commercial power to the transformer when the voltage falls below the set voltage.

[0004]

However, the X-ray high-voltage device configured as described above requires
X-ray irradiation is performed continuously while maintaining a required applied voltage to the X-ray tube while charging the capacitor intermittently. At this time, it has been found that an inrush current occurs.

[0005] That is, the supply or cutoff of the commercial power supply to the transformer is performed instantaneously, and therefore, the charging voltage to the capacitor greatly changes, and an inrush current is generated at this time.

The occurrence of such an inrush current makes it difficult to display a transparent image in a stable state.

Further, the voltage of the commercial power supply fluctuates, which adversely affects peripheral devices sharing the power supply with the X-ray high-voltage device.

Accordingly, the present invention has been made in view of such circumstances, and an object of the present invention is to provide an X-ray high-voltage device which prevents the occurrence of an inrush current during fluoroscopy. Is to provide.

[0009]

In order to achieve the above object, the present invention basically provides a transformer for boosting a voltage from a commercial power supply, a capacitor for charging an output from the transformer, An X-ray tube to which the charging voltage of the capacitor is applied, and a voltage supplied to the X-ray tube is detected, and when the detected value reaches a preset charging voltage set value, commercial power is supplied to the transformer. Detecting a voltage applied to the X-ray tube in an X-ray term voltage device comprising: a charge control unit that supplies commercial power to the transformer when the charge voltage falls below the charging voltage set value. A switching unit for intermittently turning on / off the commercial power supply to the transformer until the value reaches the charging voltage set value; and the detection value represents an on / off off time of the switching unit. In which characterized in that a control means for controlling so as to be longer toward the electrostatic voltage set value.

[0010]

The X-ray high-voltage device configured as described above has, in particular,
Switching means for intermittently turning on and off the supply of commercial power to the transformer until the detected value of the voltage applied to the X-ray tube reaches the set value of the charging voltage; The control is performed such that the charge voltage becomes longer as the charge voltage set value approaches.

Therefore, even when the supply and cutoff of the commercial power supply are performed instantaneously, the change in the charging voltage is very gentle before and after the detected value of the voltage applied to the X-ray tube reaches the charging voltage set value. become.

Accordingly, the charging current becomes gentler, and no rush current is generated.

[0013]

FIG. 1 is a schematic diagram showing an embodiment of an X-ray high voltage apparatus according to the present invention.

In FIG. 1, there is a commercial power supply 1 and a power supply from the commercial power supply 1 is a fuse 2 for overload prevention.
a, 2b, power switches 3a, 3b, supplied to the primary winding side of the high-voltage transformer 7 via the phase control circuit 4, which is specially provided in the present embodiment and will be described in detail later, and the charging switch 6, in that order. It is supposed to be.

The output on the secondary winding side boosted by the high-voltage transformer 7 is rectified through a full-bridge rectifier 8 and charged in the high-voltage capacitors 9a and 9b.

In the above-described configuration, the charging switch 6, the high-voltage transformer 7, and the full-bridge rectifier 8 constitute a high-voltage charging circuit 5.

The high-voltage capacitors 9a, 9
The high voltage charged in b is applied to the X-ray tube 11.

Further, there are voltage dividing resistors 10a, 10b, 10c and 10d for dividing a high voltage applied to the X-ray tube 11, and the voltage dividing values extracted from the voltage dividing resistors 10a, 10b, 10c and 10d are A signal corresponding to a high voltage value applied to the X-ray tube 11 is input to the charge control circuit 14.

On the other hand, a charging voltage setting value is inputted to the charging control circuit 14 by a charging voltage setting circuit 13, and the voltage dividing resistors 10a, 10b, 10
When the divided voltage value of the signal extracted from c and 10d reaches the charging voltage set value, the charging switch 6 is opened (turned off). Further, when the divided voltage value of the signal is lower than the charging voltage set value, the charging switch 6 is closed (turned on).

In this embodiment, in particular, in the phase controller 4 described above, the voltage dividing resistors 10a, 10b, 1
0c, 10d, ie, the X-ray tube 1
1 and a signal from the charging voltage setting circuit 13 are input.

FIG. 2 is a circuit diagram showing details of the phase controller 4.

In the figure, first, a signal corresponding to the voltage applied to the X-ray tube 11 and a signal from the charging voltage setting circuit 13 are input to the comparator 20 respectively.

The comparator 20 compares the respective voltage values of the respective signals, and a signal corresponding to the difference value is input to a pulse width modulator (PWH) 21.

The pulse width modulator 21 outputs a pulse having a pulse width corresponding to the difference value of the input signal.

The pulse from the pulse width modulator 21 is NP
The signal is inputted to the base of the N transistor 22.

The emitter of the NPN transistor 22 is grounded, and the collector is supplied with power via the light emitting element 23A of the photocoupler 23.

For this reason, the NP of the pulse width modulator 21
The light emitting element 23A of the photocoupler 23 blinks in response to the pulse output to the N transistor 22, and when the light emitting element 23A is turned on, the light receiving element 23B is turned on. .

On the other hand, a triac 24 is interposed in a power supply line between the power switch 3a and the charge switch 6 shown in FIG. The characteristics of the triac 24 are off at the time of the zero cross phase of the commercial power supply, and are kept off until its gate is triggered.

When the triac 24 is in the off state, an output is taken out from both ends of the triac 24 via the full bridge rectifier 25, whereby the voltage which has been full-wave rectified is Zener It is configured to be clipped via the diode 26.

The voltage clipped by the Zener diode 26 is, for example, 12 V, and this voltage is charged in the charging capacitor 27 via the light receiving element 23B of the photocoupler 23.

The light receiving element 23B of the photocoupler 23
As described above, ON / OFF is repeated by the light emitting element 23A which blinks in response to a pulse having a pulse width corresponding to the difference between the charging set value and the detection voltage.

When the charging voltage of the charging capacitor 27 reaches 1 V, for example, the uni-junction transistor 28 is turned on, and the photo-thyristor 29 is turned on through the uni-junction transistor 28.
Are turned on.

The photo thyristor 29 triggers the triac 24 to be turned on.

At this time, if the charging capacitor 27 is charged faster, the triac 24 becomes conductive more quickly (that is, the conduction phase angle becomes larger). The amount of power per unit time flowing to the rectifier 8 and the high-voltage capacitors 9a and 9b increases.

As described above, the X-ray high-voltage device shown in the present embodiment is particularly suitable for commercial use of the high-voltage transformer 7 before the detected value of the voltage applied to the X-ray tube 11 reaches the charging voltage set value. A triac 2 for intermittently turning on / off the power supply is provided so that the on / off off time becomes longer as the charging voltage set value is approached.

Thus, even if the supply and cutoff of the commercial power supply is performed instantaneously, the change in the charging voltage is very gentle before and after the detected value of the voltage applied to the X-ray tube reaches the charging voltage set value. become.

Accordingly, the charging current becomes gentler, and no rush current is generated.

In the above-described embodiment, the switching of the commercial power supply to the transformer is performed by using the triac 24. However, the present invention is not limited to this, and other switching elements may be used. Good.

In short, switching means for intermittently turning on / off the commercial power supply to the transformer before the detected value of the voltage applied to the X-ray tube reaches the charging voltage set value is provided. The on / off off time may be configured to be longer as the charging voltage set value is approached.

[0040]

As is apparent from the above description,
ADVANTAGE OF THE INVENTION According to the X-ray high voltage apparatus by this invention, generation | occurrence | production of an inrush current can be prevented at the time of fluoroscopy.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of an X-ray high voltage device according to the present invention.

FIG. 2 is a circuit diagram showing one embodiment of a phase control circuit used in the X-ray high-voltage device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Commercial power supply, 4 ... Phase control circuit, 5 ... High voltage charging circuit, 6 ... Charge switch, 7 ... High voltage transformer, 8 ... Full bridge rectifier, 9a, 9b ... High voltage capacitor, 11 ...
X-ray tube, 12: charging voltage detector, 13: charging voltage setting circuit, 14: charging control circuit

Claims (1)

(57) [Claims] A transformer for boosting a voltage from a commercial power supply, a capacitor for charging an output from the transformer, an X-ray tube to which a charging voltage of the capacitor is applied,
When the voltage applied to the X-ray tube is detected, and when the detected value reaches a preset charging voltage set value, the supply of commercial power to the transformer is cut off and when the charged voltage falls below the charging voltage set value. An X-ray high-voltage device comprising: a charging control unit that supplies commercial power to the transformer; wherein the detection value of the voltage applied to the X-ray tube reaches the charging voltage set value until the detection value of the voltage is applied to the X-ray tube. Switching means for intermittently turning on / off the commercial power supply to the transformer; and control means for controlling the on / off time of the switching means to be longer as the detected value approaches the charging voltage set value. X-ray high-voltage device characterized by the above-mentioned.