JPH0676982A - Monotank x-ray power supply device - Google Patents

Abstract

PURPOSE:To provide capability of accurately setting a high voltage value and maintain uniform product quality, regarding a monotank X-ray power supply device. CONSTITUTION:The resistor of a voltage divider in a high voltage circuit is constituted of three components of an upper resistor 35 having a high resistance value, a lower resistor 37 and adjusting variable resistor 38, and a voltage dividing ratio is measured and recorded in advance. Then, the resistor is oil immersed and sealed in a tank section 103. The value of high voltage output is available as the reciprocal of the dividing voltage ratio multiplied by the value of reference voltage 54.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mono-tank type X-ray power supply device capable of accurately setting an output voltage and performing self-measurement when a high voltage generator and an X-ray tube are enclosed and mounted in the same insulating oil tank. .

[Prior Art and Problems to be Solved by the Invention]
To reduce the size of dental x-ray equipment, the high-voltage generator and the x-ray tube are often integrated and enclosed in an insulating oil tank or the like. In that case, in order to stabilize the value of the generated high voltage and set it accurately, a voltage divider with a high resistance resistor is provided in the insulating oil tank, and the detection voltage and reference voltage obtained by this voltage divider are A circuit for comparing and stabilizing is provided. However, the accuracy of this high resistance resistor is ±
It is generally about 5%, and it is costly to obtain higher accuracy. On the other hand, for an X-ray device, this high voltage output is usually required to have an accuracy of ± 1% or less. Therefore, the adjustment method is to deal with the error of the voltage divider by changing the corresponding value of the reference voltage of the control circuit. ing. Therefore, it becomes impossible to uniquely set the voltage corresponding to the reference voltage. Furthermore, since the resistance value of a high resistance resistor when a predetermined high voltage is applied is different from the resistance value when a low voltage is applied, calibration becomes more difficult. SUMMARY OF THE INVENTION It is an object of the present invention to obtain a function of accurately setting a high voltage output and performing self-measurement in a monotank type X-ray power supply device with a small and economical structure.

In order to solve this problem, the present invention discloses that a high voltage detecting voltage divider is housed in a tank, which is adjusted in advance to a constant partial pressure ratio and sealed oil is immersed. It is a proposal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a monotank type X-ray power supply device according to the present invention will be described with reference to FIG. This mono-tank type X-ray power supply device is composed of an inverter section 101 and a tank section 103. In the tank section 103, a high voltage generating section 33 and an X-ray tube 31 are filled with insulating oil. In the inverter unit 101, 100V of commercial AC power is received from the input terminals 1 and 2, rectified by the rectifier circuit 5, and smoothed by the smoothing capacitor to obtain DC. This DC voltage is converted into a high frequency of about 100 KHz by the inverter circuit 9 composed of four field effect transistors 9a, 9b, 9c, 9d and output to terminals 13 and 15. In the tank section 103, terminals 17 and 19 for input are used.
And are connected to the terminals 13 and 15 of the inverter section and supplied to the primary winding of the transformer 21. The high frequency high voltage boosted by the secondary winding of the transformer 21 is a multi-stage voltage doubler rectifier circuit 23 that produces a positive output and a multi-stage voltage doubler rectifier circuit 25 that produces a negative output.
Connected to. The output terminal 27 of the multistage voltage doubler rectifier circuit 23 is connected to the anode of the X-ray tube 31,
The output terminal 29 of 25 is connected to the cathode of the X-ray tube 31. Although not shown, the filament of the X-ray 31 is supplied with electric power by an insulated power source. The output terminal 27 of the multistage voltage doubler rectifier circuit 23 is connected to a voltage divider composed of a high resistance resistor 35, a resistor 37, and a variable resistor 38, many of which are connected in series. A capacitor 39 is connected in parallel with the high resistance resistor 35, and a capacitor 41 is connected in parallel with the resistor 37 and the variable resistor 38 connected in series. The capacitors 39 and 41 serve to flatten the frequency characteristic of voltage division. The signal thus divided is sent to the terminals 43 and 45. This terminal 43 and terminal
45 is connected to the terminal 47 and the terminal 49 of the inverter unit 101, respectively. The terminal 47 is connected to the minus input terminal of the operational amplifier 50, and the terminal 49 is connected to the internal common ground.
A reference voltage 54 is connected between the + input terminal of the operational amplifier 50 and the common ground. The output terminal of the operational amplifier 50 is a control circuit
It is connected to 95 and controls the inverter circuit 9 so that the output voltage becomes a predetermined value. A method of calibrating the output voltage of the high voltage generator 33 in the present apparatus configured as described above will be described. First, the tank 103 or another container is filled with insulating oil in advance, and a part of it is opened to release the high voltage output terminal 27.
Connect a voltmeter to. A high impedance voltmeter is also connected between terminals 43 and 45. In this state, terminals 17 and 19
A high frequency voltage is applied between and to generate a high voltage. The variable resistor 38 is adjusted so that the ratio of the voltage value generated at the high voltage output terminal 27 and the voltage value generated between the terminals 43 and 45 becomes a predetermined value. After this adjustment, the tank section 103 is closed. When the voltage division ratio of the voltage divider composed of the high resistance value resistor 35, the resistor 37 and the variable resistor 38 is 1 / α and the voltage of the reference power source 54 is E, the output voltage generated at the high voltage output terminal 27. Becomes .alpha.E, and the voltage division ratio 1 / .alpha. Is calibrated in advance as described above, so that the output voltage can be uniquely set with high accuracy in proportion to the reference voltage E. Regarding the variable resistor 38,
By exchanging with a combination of fixed resistors so as to obtain a calibrated resistance value, it is possible to eliminate the variable elements peculiar to the variable resistors and achieve higher accuracy and higher stability.

The present invention has the characteristics as described above, and after calibration, the output voltage can be uniquely set according to the value of the reference voltage. In other words, it corresponds to the built-in high voltage output voltmeter. And, it has the following effects. Since the voltage divider for high-voltage detection plays the role of a measurement function, a dedicated multiplier for voltage measurement is not required, and it is compact and economical. The deviation of each resistor that constitutes the voltage divider for high voltage detection is corrected by the calibration work. Therefore, despite the fact that the resistor is of a general deviation value class, the measurement accuracy is kept high and the component cost is high. About is economical. When calibrating by applying a high voltage of the rated value, the voltage dependence of the high resistance resistor is also corrected, resulting in higher measurement accuracy. Since the ratio of the voltage divider for high voltage detection is calibrated to a constant value,
Inverters and tanks are compatible between products of the same model, improving maintenance efficiency.

[Brief description of drawings]

FIG. 1 shows an embodiment of a monotank type X-ray power supply device according to the present invention.

[Explanation of symbols]

1, 3 ... Input terminal 5 ... Rectifier circuit 7 ... Smoothing capacitor 9 ... Inverter circuit 13, 15, 17, 19 ... Terminal 21 ... Transformer 23, 25 ... Multistage voltage doubler rectifier circuit 27, 29 ... Output terminal 31
… X-ray tube 33… High voltage generator 35… High resistance resistance 37… Resistor
38 ... Variable resistors 39, 41 ... Capacitors 43, 45, 47, 49 ... Terminals 50 ...
Operational amplifier 54 ... Reference voltage 101 ... Inverter section 103 ... Tank section

Claims (1)

[Claims] 1. A mono-tank type X-ray power supply device in which a high-voltage generator and an X-ray tube are enclosed and mounted in the same insulating oil tank, and a voltage divider for high-voltage detection is housed in the tank. A monotank type X-ray power supply device characterized by adjusting a certain partial pressure ratio and immersing in sealed oil.