JPH1083892A - X-ray high voltage generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the efficiency of adjustment work for compensating the phase of a high voltage divider for stabilizing output voltages in an X-ray high voltage generating device. SOLUTION: A high voltage generator circuit 5 and a high voltage divider 6 are placed within an oil tank 4. The high voltage divider 6 comprises a resistor 7 and a series circuit of a resistor 12 and a variable resistor 13. A voltage detected at a dividing point B is fed to a control circuit 3, and a power converting part 2 is controlled so that an output voltage attains a predetermined value. A phase correcting capacitor is adjusted so that the voltage at the dividing point B shows a flat dividing characteristic in terms of both direct and alternating current with respect to an output point A. An axial rotation type DIP switch 20 and capacitors 15, 16, 17, 18, 19 are connected between the dividing point B and ground, and by rotating the axial rotation type DIP switch 20, the phase compensating capacitor can be set to an optimum adjusted value in one behavior.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high voltage generator for X-rays, and more particularly to a high voltage generator for an X-ray, which has a built-in high voltage generator in an oil tank. The high-voltage divider in the oil tank of the high-voltage generator for X-rays, which stabilizes the high voltage by controlling the inverter with this detection signal, and the adjustment structure for the X-ray The present invention relates to a voltage generator.

[0002]

2. Description of the Related Art Since a high voltage generator for X-rays generates an output of several tens of kilovolts, in order to stabilize the voltage detected by a voltage divider to several volts, the voltage divider must be of the order of several thousandths. It becomes the partial pressure ratio. With this large voltage division ratio, simply using a resistor alone does not equivalently make a proportional voltage divider based on pure resistance, but may have a characteristic of a differential circuit in which a large amount of capacitance is distributed. If a stabilizing feedback loop is formed with this characteristic, the feedback loop becomes unstable. Therefore,
The high-voltage divider is not a simple resistor divider but uses a phase-correction capacitor in parallel with the divider to improve the frequency characteristics.

The value of the phase correction capacitor on the high voltage side is at least several tens of pF in order to cancel the effect of the distributed capacitance. Therefore, as for the value of the phase correction capacitor on the low voltage side, it is necessary to make the AC voltage dividing ratio substantially equal to the DC voltage dividing ratio. Therefore, a value obtained by multiplying a value (several thousands) close to the inverse ratio of the voltage division ratio by the value of the high-voltage side phase correction capacitor and several tens of pF, that is, about several hundred nF is obtained.

[0004] Furthermore, since an X-ray apparatus takes a short time of several milliseconds, a high-voltage generator may be required to have a fast voltage rising characteristic of 1 ms or less. In order to obtain the high-speed rise characteristic, a high-speed response of the high-voltage detection circuit is required. For that purpose, the adjustment of the phase correction capacitor is important.

[0005]

However, attaching the low-voltage side resistor and the low-voltage side phase correction capacitor to the outside of the tank has the following problems. Since the value of the phase correction capacitor on the low voltage side is usually on the order of several hundred nF, it is difficult to realize a variable capacitor (a so-called variable condenser), and cut and try adjustment is performed by soldering individual parts, which requires a lot of adjustment time. To mount the low-voltage side resistance and low-voltage side phase correction capacitor on the printed circuit board and place it on the oil tank, machining of the tank top plate is required. Further, a cover is required to protect the printed circuit board. Furthermore, a relay connector for sending a signal to the inverter is required separately from a connector for extracting a signal line from the oil tank.

The present invention solves these problems,
Change the low-voltage side phase correction capacitor not by changing the capacitor,
Adjustable by one action work, and while placing the low voltage side resistance and low voltage side phase correction capacitor inside the tank,
An object of the present invention is to enable easy and low-cost machining without removing a top plate.

[0007]

Means for Solving the Problems In order to solve this problem, the following means are proposed. First, as a first means, a high voltage generating circuit is built in an oil tank, and a high voltage output for X-rays is detected by a high voltage divider composed of a high voltage resistor and a low voltage resistor each having a phase correction capacitor connected in parallel. In a high-voltage generator for X-rays, which controls an inverter with this detection signal to stabilize a high voltage, a plurality of capacitors having different capacities are selectively connected to a low-voltage side of a high-voltage divider and the capacitors are selectively connected to a low-voltage resistor. A high-voltage generator for X-rays, characterized in that a selection switch is provided and the selected capacitor is used as all or a part of the low-voltage side phase correction capacitor so that the phase error can be adjusted to a series of stepwise values. Suggest a device.

[0008] As a second means, all or a part of the low-voltage side resistance of the high-voltage divider is fixed as a shaft-rotating variable resistance so that the rotor faces upward immediately below the tank top, and Adjusting the above variable resistance with the top plate fixed to the tank body, adjusting the above variable resistance just above the variable resistance, and adjusting the variable resistance after correcting the error of the high side detection resistance We propose a structure that can seal screw holes with screws.

As a third means, it is proposed that the selection switch is a shaft rotation type dip switch, and a small number of capacitors are digitally added to be selectable.

[0010] As a fourth means, a low-voltage side resistance and a low-voltage side phase correction capacitor are arranged in an oil tank, and a rotor of a shaft rotary type dip switch is arranged so that the rotor faces upward just below a tank top plate. Adjust the above rotor with the top plate fixed to the tank body by fixing it and providing a screw hole for the diameter that allows the rotation tool to be inserted directly above the rotor of the oil tank top plate, and correcting the phase error After that, we propose a structure in which the screw holes for adjustment can be sealed with screws.

[0011]

FIG. 1 shows an embodiment of an X-ray high voltage device according to the present invention. In the figure, reference numeral 1 denotes an inverter unit including a power conversion unit 2 and a control circuit 3, and reference numeral 4 denotes an oil tank unit including a high voltage generation circuit 5 and a high voltage divider 6. The high voltage divider 6 includes a high-side resistor 7 and a high-side phase correcting capacitor 8 in parallel with the high-side resistor 7, a low-side resistor and a low-side phase correcting capacitor.

The low-voltage side resistor is a variable resistor in whole or in part, and is adjusted so as to divide a high voltage at a predetermined ratio. In FIG. 1, the low-voltage side resistor includes a resistor 12 and a variable resistor 13.
And a series circuit.

[0013] The low-voltage side phase correction capacitor is composed of a fixed capacitor 15, an adjustment capacitor, 16, 17, 18, and 19 and a shaft rotating type.
It comprises a DIP switch 20. The low-voltage phase correction capacitor changes the frequency characteristic that affects the rising characteristic of the high-voltage output. This adjustment differs for each oil tank due to an error in the component constant of the high-pressure side resistor 7 and the high-pressure side phase correction capacitor 8, and is a unique adjustment value. The fixed capacitor 15 is selected to have a minimum value calculated in consideration of the variation of components, and the adjusting capacitors 16, 17, 18, and 19 are selected to have a value that can absorb the above-described variation and its own variation.

The value of the phase correction capacitor is adjusted so that the voltage at the voltage dividing point B has a flat voltage dividing characteristic with respect to the output point A both in DC and AC. Assuming that the value of the high-voltage side phase correction capacitor 8 is several tens of pF and the voltage division ratio is about several thousandths, the optimum value of the low-voltage side phase correction capacitor is as follows.
This is a value obtained by multiplying the value of the high-voltage side phase correction capacitor 8 by a value (thousands) close to the inverse ratio of the voltage division ratio, that is, several hundred nF. The fixed capacitor should be set to the upper and lower values including this optimum value.
15 and the values of the adjusting capacitors 16, 17, 18, and 19 are selected in advance.

The shaft rotation type DIP switch 20 is a 16-bit type, and among the low-voltage side phase correction capacitors, adjustment capacitors 16, 17, 18, and 19 are distributed at a capacitance ratio of 1, 2, 4, and 8, Connect to each terminal of the corresponding shaft rotation type DIP switch 20. That is, by adjusting the rotation of the shaft rotation type DIP switch 20, the capacity can be changed in 16 steps from 0 unit to 15 units. All the components of the high-voltage divider 6 are housed in the oil tank unit 4. At this time, the low-voltage side resistor 9 and the low-voltage side phase correction capacitor 10 must be adjustable in order to correct the component constant error between the high-voltage side resistor 7 and the high-voltage side phase correction capacitor 8.

The reason why the adjustment is performed for each tank is that the production system and the service system of the inverter type high voltage generator for X-rays are convenient. That is, during production,
The inverter unit 1 and the oil tank unit 4 can be adjusted separately by a flow operation, and can be shipped in combination with an arbitrary inverter unit 1 and the oil tank unit 4. Further, when the inverter unit 1 or the oil tank unit 4 fails on the user side, only the failed inverter unit 1 or the oil tank unit 4 is replaced, so that there is an advantage that the working time is shortened.

FIG. 2 is a partial view showing the structure of the high-voltage generator for X-rays according to the present invention, and shows an embodiment of the mounting arrangement in the oil tank unit 4 of the circuit of the low-voltage side resistance and the low-voltage side phase correction capacitor. Is shown. In the figure, a variable resistor 13 is mounted on a printed circuit board 22 and its rotor 14 is mounted on a tank top plate.
It is arranged toward 24. Similarly, a rotary DIP switch 20
Are also mounted on the printed circuit board 22, and the rotor 21 is arranged so as to face the tank top plate 24.

On the other hand, the top plate 24 has a screw hole 25 at a position facing the rotor 14 of the variable resistor 13. The same applies to the shaft rotation type DIP switch 20. Top 24
Since this embodiment is a thin iron plate, a screw hole 25 is provided in the backing plate 23 along the slightly thicker iron backing plate 23 on the lower side. The diameter of the screw hole 25 is a diameter through which a rotor adjustment tool, for example, an adjustment driver passes, for example, 6 m.
After making necessary adjustments by operating the variable resistor 13 and the shaft rotation type DIP switch 20 through these screw holes, screw holes 25
Is sealed with screws 26. A rubber packing 27 is provided at the base of the screw 26 for oil sealing. Note that, instead of the rubber packing 27, other oil sealing means, for example, sealing with an adhesive may be used.

[0019]

As described above, according to the present invention, the phase correcting capacitor can be adjusted stepwise in one behavior.
Soldering work while selecting a conventional individual capacitor can be omitted. When the low-pressure side resistance and the low-pressure side phase correction capacitor are provided in the oil tank, it is not necessary to mechanically protect the oil tank, and the signal can be directly transmitted to the inverter without relaying the signal. In addition, while the high-side resistor and the low-side phase correction capacitor are arranged inside the tank, the adjustment can be performed easily and at low cost by machining without removing the top plate. Also, the oil tank can be adjusted independently.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment of an X-ray high voltage generator according to the present invention.

FIG. 2 is a partial view showing a structure of an X-ray high voltage generator according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inverter part 2 ... Power conversion part 3 ... Control circuit 4
... Oil tank part 5 ... High voltage generating circuit 6 ... High voltage divider 13 ... Variable resistor 20 ... Shaft rotation type DIP switch 22 ... Printed circuit board

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroyuki Etsu 1-18-1 Takada, Toshima-ku, Tokyo Origin Electric Co., Ltd.

Claims (4)

[Claims] 1. A high voltage generating circuit is built in an oil tank,
An X-ray that detects a high-voltage output for X-rays with a high-voltage divider composed of a high-voltage resistor and a low-voltage resistor each having a phase correction capacitor connected in parallel and controls the inverter with this detection signal to stabilize the high voltage In the high voltage generator, a plurality of capacitors having different capacities and a selection switch for selectively connecting the capacitors to the low voltage side resistor are provided on the low voltage side of the high voltage voltage divider, and the selected capacitor is connected to all or one of the low voltage side phase correction capacitors. A high-voltage generator for X-rays, wherein a phase error can be adjusted to a series of stepwise values by using the unit as a unit. 2. The high-voltage generator for X-rays according to claim 1, wherein all or a part of the low-voltage side resistance of the high-voltage divider is a shaft-rotation type variable resistance, and the rotor is directed upward immediately below the tank top plate. The variable resistance is adjusted with the top plate fixed to the tank body, and an adjustment screw hole with a diameter that allows the rotation tool to be inserted is provided directly above the variable resistance on the oil tank top plate. A high-voltage generator for X-rays, wherein the adjustment screw hole is sealed with a screw after correcting an error in the side detection resistor. 3. The high-voltage generator for X-rays according to claim 1, wherein the selection switch is a shaft-rotation type dip switch, and a small number of capacitors are digitally added to be selectable. Characteristic high-voltage generator for X-rays. 4. A high-voltage generator for X-rays according to claim 1, wherein the low-voltage side resistance and the low-voltage side phase correction capacitor are arranged in an oil tank, and the shaft rotation type is provided. The rotor of the dip switch is fixed directly below the tank top plate so that the rotor faces upward, and an adjustment screw hole with a diameter that allows the rotation tool to be inserted just above the rotor of the oil tank top plate is provided. A high voltage generator for X-rays, characterized in that the rotor is adjusted while fixing the rotor to the tank body, and the adjusting screw hole is sealed with a screw after correcting the phase error.