JPS6028725A - X-ray high voltage device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an X-ray high voltage device that generates a high voltage to be applied to an X-ray tube.

[Technical background of the invention and its problems]

The high voltage to be applied to the X-ray tube, that is, the tube voltage (hereinafter referred to as "tube voltage") applied between the anode and filament of the X-ray tube, is made by intermittent DC voltage at a specific frequency,
This intermittent DC voltage is applied to the primary side of a transformer, which is a high voltage generating means, and is obtained by rectifying the voltage induced on the secondary side of the transformer. As shown in FIG. 1, the method for obtaining the DC voltage involves rectifying the AC voltage source 1 with a rectifier consisting of thyristors 2a, 2a and diodes 2b, 2b, and then smoothing it with a capacitor B. There is a first method of obtaining the battery, and a second method of using a storage battery 5 charged by charging means 4, for example, a charger, as shown in FIG. 2, and these methods have been commonly used in the past.

However, in the first method (FIG. 1), phase control is performed by the thyristor 2a l 2& as a measure against surge current when the AC voltage source 1 is turned on, and the charging current to the capacitor 3 is As shown by Id in Figure 6, the pulse current is every 10 m5ec (power supply frequency 5
Cyrisk 2a, 2a during full wave rectification at 0Hz
(because the turn-on period of is iQmsec). As a result, the average current of the pulsed current is reduced by the current flowing to the anode of the X-ray tube (hereinafter referred to as "
When the tube current (referred to as "tube current") is large, that is, when high exposure of ), the tube voltage drops, resulting in an insufficient amount of incident X-rays, resulting in insufficient photographic darkening. As a countermeasure for such drawbacks, the capacity of the AC voltage source 1 (usually supplied by a dedicated power supply facility using a transformer),
Although it is possible to increase the capacitance of the capacitor 6 and the capacitor 6, it requires a large-scale change in the power supply equipment, the capacitor 3 becomes larger, and the high frequency noise generated by the switching element is not mixed into the power supply line. Considering that a large noise filter is essential for
If so, the device will inevitably be large, heavy, and expensive.

Furthermore, since the second method (FIG. 2) uses the charging means 4, for example, the storage battery 5 that has been charged in advance by a charger, if the power line is disconnected, high-frequency noise generated by the switching element is disconnected. Since the noise can be prevented from entering the power supply line, the large noise filter described above becomes unnecessary.

However, the internal resistance of a storage battery changes greatly depending on whether it is charged or discharged, so in order to provide stable X-ray exposure for a long time with a single charge, it is necessary to
It is necessary to use several storage batteries, which inevitably increases the size and weight of the device, as well as making it expensive. Furthermore, when exposed to high levels of X-rays, a large instantaneous current is discharged from the storage battery, resulting in problems such as shortening the life of the expensive storage battery.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and does not cause problems such as insufficient photographic darkening even though the AC voltage is supplied from a small-capacity power supply equipment, and the device itself is small.
It is an object of the present invention to provide an X-ray high voltage device that is lightweight and has a long life.

[Summary of the invention]

The outline of the present invention for achieving the above object is as follows: a charging means that inputs an AC voltage source; a DC voltage source that outputs a DC voltage based on the output of the charging means; and a DC voltage source that outputs a DC voltage from the DC voltage source. The high voltage to be applied to the X-ray tube includes at least a switching element that intermittents the voltage at a specific frequency, and a high voltage generating means that receives the DC voltage that is intermittent by the switching element and generates a high voltage. A DC voltage source comprising a storage battery, a discharge limiting means for limiting discharge of the storage battery, a capacitor connected in parallel to the storage battery via the discharge limiting means, and the AC The present invention is characterized in that a switch is provided between the voltage source and the discharge limiting means, which opens and closes in conjunction with X-ray exposure.

[Embodiments of the invention]

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

FIG. 4 is a circuit diagram showing the configuration of the X-ray high voltage apparatus according to the present invention, and FIG. 1 shows an AC voltage source supplied from a power supply facility (not shown). The AC voltage source 1 includes charging means 4
, for example, is connected to the input side of a charger, and the output side of this charging means 4 is connected to a storage battery 5 disposed at a subsequent stage. In addition, 8 is a capacitor 1, for example, a double switch (hereinafter simply referred to as a "switch" 1r) that can be opened and closed by a control signal output from an X-ray exposure control device (not shown), etc. 6 and is connected in parallel to the storage battery 5 via a discharge limiting means 7 that limits the discharge current of the storage battery 5. However, the storage battery 5. The discharge limiting means 7 and the capacitor 8 constitute a DC voltage source 15. The output of this DC voltage source 15 is connected to be applied to the input side of the high voltage generating means 100 via a switching element, for example a transistor 9, which opens and closes at a specific frequency. The high voltage generating means 10 is, for example, a primary one.

It consists of a transformer (not shown) having a secondary winding, and a rectifier (not shown) that rectifies the high voltage induced in the secondary winding, and its output is sent to the anode 12a of the X-ray tube 12.
and the filament 12b, and some of them, namely the resistors 11a and Il.
The control means 16 is connected so that the voltage divided by the voltage dividing means configured by connecting the two in series with each other is applied to the control means 16. This control means 13 includes the high voltage generation means 1D.
The driver 14 arranged at the subsequent stage is controlled according to the fluctuation of the output voltage. The driver 14 generates a pulse voltage applied to the base of the transistor, and the pulse width is controlled by the control means 13.

Next, the configuration of the discharge limiting means 7 will be explained. FIG. 5 is a circuit diagram showing the configuration of the discharge limiting means 7,
The voltage of the storage battery 5 is connected to be applied to the capacitor 8 via the switch 6 and a resistor 76 connected in series thereto. Further, the detection means 76 connected in parallel to the capacitor 8 is composed of, for example, a comparator using an operational amplifier or a Zener diode, and detects the terminal voltage of the capacitor 8, and its output is sent to the relay 72. The signal is input to a driver 75 that drives the .

One end of the relay 72 is connected to the output side of the driver 75, and the other end is connected so that the voltage of the storage battery 5 is applied via the switch 6, and its normally open contact 72a is connected to the resistor 76. are connected in parallel.

Next, the operation of the apparatus configured as described above will be explained. When X-rays are not irradiated, the switch 6 is turned on (conducting state), and the discharge current of the storage battery 5 charged by the charging means 4 is charged to the capacitor 8 via the switch 6 and the discharge limiting means 7.

Therefore, when the terminal voltage of the capacitor 8 is intermittently applied to the high voltage generating means 10 by the driver 14 through the transistor 9 which opens and closes at a constant frequency of υ% during xmm radiation, the high voltage generating means 10 generates high voltage. This high voltage is applied between the anode 12& of the X-ray tube 12 and the filament 12b (this high voltage is also referred to as "tube voltage"), and after being divided by the resistors 11a and 11b, it is controlled. applied to means 16. The control means 16 is
The pulse width of the pulse voltage applied to the base of the transistor 90 is controlled according to fluctuations in the divided voltage. That is, feedback control is performed by the control means 16 so as to keep the tube voltage constant. Therefore, even if the terminal voltage of the capacitor 8 gradually decreases as the X-ray exposure time passes, the tube voltage is kept approximately constant by the feedback control.

Next, the operation of the discharge limiting means 7 will be explained. The switch 6 is turned on during X-ray exposure. therefore,
At this time, the capacitor 8 is charged by the discharge current of the storage battery 5 via the resistor 76 and the diode 74. When the terminal voltage of the capacitor 8 exceeds a specific voltage, the detection means 76 detects this and drives the relay 72 via the driver 75. Due to the operation of the relay 72, the normally open contact 72a of the relay 72 is closed, so the resistance 73
Both ends of are shorted. As a result, the capacitor 8 becomes
It will be charged at zero ohms. \\, Here, the reason for charging the capacitor 8 in two stages will be explained.

That is, the discharge current of the storage battery 5 instantaneously becomes a large current due to the rush current when charging the capacitor 8, and if this is repeated, the life of the storage battery 5 will be shortened. Therefore, when the terminal voltage of the capacitor 8 is less than a specific voltage, the inrush current is alleviated by charging via the resistor 76. Therefore, the energy at the time of X-ray irradiation uses the discharge current of the capacitor 8, and rapid discharge of the storage battery 5 is avoided, so compared to the conventional case (Fig. 2), the storage battery 5
The lifespan of can be significantly extended.

Next, at the time of X-ray irradiation, the switch \6 is turned off (non-conductive state), the storage battery 5 is disconnected from the DC voltage source 15, and X-ray irradiation is performed in this state. Therefore, the capacitor 8 only needs to have a charging capacity within a range that can compensate for the energy of one X-ray exposure through feedback control. Furthermore, since the switch group 6 is turned off when the X-rays are irradiated, it is possible to prevent high frequency noise caused by the opening and closing operations of the transistor 9 from entering the power supply line, thereby eliminating the need for a noise filter or the like.

Furthermore, after one X-ray exposure is completed and until the next exposure, the switch 6 is turned on and the capacitor 8 is charged, but this charging current, that is, Q=I・T(=CV) As shown in FIG. 7, the charging current (Ib) obtained from the relationship can be larger than the average current If in FIG. 1, so that the battery can be charged in a short time. Therefore, unlike the conventional device (FIG. 1), problems such as insufficient photographic darkening caused by insufficient charging current for the capacitor 6 do not occur.

Furthermore, unlike the conventional system (FIG. 1), this device does not directly use the rectified AC power source 1, but instead uses the AC power source 1 that has been temporarily stored in the storage battery 5. The equipment does not need to have a large capacity. Further, since the storage battery 5 is constantly charged by the charging means 4, the storage battery 5 and the charging means 4 do not need to have large capacities.

It goes without saying that the present invention is not limited to the embodiments described above, and that modifications can be made as appropriate within the scope of the gist of the present invention. An example of this will be described below.

Although the charge limiting means 7 shown in FIG. 5 uses a relay 72, it is also possible to use a transistor 78 as shown in FIG. 6, for example. This takes advantage of the fact that the transistor 78 is turned on and the collector-emitter resistance becomes almost zero ohm. Further, although not shown, in addition to the transistor 78, a triac or the like may be used, or phase control (soft start) using a thyristor may be used.

Further, in the embodiment, the switch 6 is provided between the storage battery 5 and the discharge limiting means 7, but the switch 6 is not limited to this, and as shown in FIG. 8, the switch 6 is provided between the charging means 4 and the storage battery 5. It may be provided. With this configuration, the storage battery 5 can be charged only when X-rays are not irradiated, but the X#* radiation energy is supplied from both the capacitor 8 and the storage battery 5, and a large amount can be charged in a short period of time. This is very effective when taking out a capacitive load. Further, in this case, the high voltage generating means 10
It is conceivable that back electromotive force generated in the second winding of a transformer (not shown) or the like may have an adverse effect on the storage battery 5. In such a case, for example, a diode shown at 16 may be inserted to prevent reverse charging of the storage battery 5.

Furthermore, although not shown, the switch 6 is connected to the AC voltage source 1.
Even if it is provided between the charging means 4 and the charging means 4, the same effect as shown in FIG. 8 can be obtained.

〔Effect of the invention〕

According to the present invention described above, by connecting a capacitor in parallel to the storage battery through the discharge limiting means, the charging efficiency of the capacitor is improved, so that problems such as insufficient photographic darkening caused by insufficient charging current, etc. Problems do not occur, and the storage battery, capacitor, and charging means do not need to be large, and noise filters and the like are not required, so the device itself is small and small in size. Since rapid discharge can be avoided, it is possible to provide an X-ray high voltage device that has excellent effects such as a long life.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit diagrams showing the DC power supply of a conventional X-ray high voltage device, Figure 3 is a waveform diagram to explain the characteristics of the DC voltage source shown in Figure 1, and Figure 4 is a diagram of the main The circuit diagrams, FIGS. 5 and 6, showing the configuration of the X-ray high voltage device according to the invention are shown in FIG.
7 is a waveform diagram for explaining the operation of the device shown in FIG. 4, and FIG. 8 is a modification of the device shown in FIG. 4. FIG. 4...Charging means, 5...Storage battery, 6...Switch, X-ray tube, 15...DC voltage source.

Claims (1)

[Claims] A charging means that inputs an AC voltage source, a DC voltage source that outputs a DC voltage based on the output of the charging means, a switching element that intermittents the DC voltage output from the DC voltage source at a specific frequency, and An X-ray high-voltage apparatus that generates a high voltage to be applied to an X-ray tube, which includes at least a high-voltage generating means that receives a DC voltage that is intermittent by a switching element and generates a high voltage, includes a storage battery, and A DC voltage source including a discharge limiting means for limiting discharge of a storage battery, and a capacitor connected in parallel to the storage battery via the discharge limiting means, and an X voltage between the AC voltage source and the discharge limiting means. An X-ray high voltage device characterized by comprising a switch that opens and closes in conjunction with radiation exposure.