JPH11111177A - X-ray tube manufacturing method - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a method for manufacturing an X-ray tube, which suppresses the occurrence of an undesired discharge and is less likely to cause damage to the X-ray tube and damage to the X-ray tube manufacturing apparatus body. According to a method of manufacturing an X-ray tube of the present invention, X-ray
In evacuation, aging or withstand voltage tests of wire tubes,
When a discharge occurs (B), the tube voltage applied between the anode and the cathode, which generates a tube current flowing between the anode and the cathode of the X-ray tube, is cut off (C). After applying a tube voltage (D) lower than the tube voltage at which the generation of the X-ray tube has occurred, detecting that the magnitude of the tube current is smaller than a predetermined value, and confirming that the degree of vacuum in the X-ray tube has not decreased ( E) By applying a predetermined tube voltage (F), damage to the X-ray tube can be reduced, and damage to the X-ray tube manufacturing apparatus body can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an X-ray tube, and more particularly to protection of an X-ray tube immediately after a high voltage discharge and an apparatus for manufacturing the X-ray tube.

[0002]

2. Description of the Related Art Generally, in a manufacturing process for manufacturing an X-ray tube, the anode of the X-ray tube is heated with an electron beam and an exhaust process for discharging gas from the anode or the electron beam is made to collide with the anode to produce a surface of the anode. In a process such as an aging process for adjusting (smoothing) a state, a high voltage called a tube voltage is applied between an anode and a cathode in order to generate an electron beam from a cathode. In addition, a similar tube voltage is applied in a withstand voltage test process for guaranteeing quality.

In the X-ray tube manufacturing apparatus shown in FIG.
First, a predetermined filament current (arrow) 5 is supplied from a filament power supply 4 to the cathode filament 2 of the X-ray tube 1 whose inside is maintained at a high vacuum, and the cathode filament 2 is heated by the filament current.

In this state, a predetermined voltage is applied between the anode 3 and the cathode (cathode filament) 2 by the high-voltage transformer 7 connected to the tube voltage control power supply 6 so that the anode 3 becomes positive (positive) in potential. Is applied.

As a result, an electron beam E proportional to the temperature of the cathode filament 2 is generated from the cathode 2 and collides with the anode 3. Therefore, a tube current (arrow) 9 flows in the circuit in a direction opposite to the electron beam E.

The magnitude of the electron beam E is controlled by feeding back the magnitude of the tube current 9. That is,
When the tube current 9 flows through the resistor 10, a voltage (arrow) 11 is generated across the resistor 10. Since this voltage usually has a ripple, it is converted by the converter 12 into a complete DC.

The converted DC signal (arrow) 13 is used as a CPU (main controller) 14 for controlling the entire X-ray tube manufacturing apparatus.
Is input to The CPU 14 controls the output of the filament power supply 4 so that the DC signal becomes equal to the set value.

The CPU 14 outputs a control signal (arrow) 15 to the tube voltage control power supply 6,
Is controlled to be a set value. In this way,
In the X-ray tube manufacturing apparatus, the magnitude of the tube voltage applied between the anode and the cathode filament and the magnitude of the tube current flowing between the two electrodes due to the tube voltage are connected to the internal memory or CPU of the CPU 14 in advance. The size is controlled so as to be the size stored in the memory.

If the magnitude of the tube current 9 exceeds a predetermined value and is abnormally large, the CPU 14 determines that a discharge has occurred between the anode 3 and the cathode 2 and shuts off the output of the tube voltage control power supply 6. Then, after a certain period of time, re-enter.

[0010]

However, in the method of controlling the manufacturing apparatus described above, the quality is insufficient.
In each step of applying the above-described tube voltage (high voltage) in the tube, dielectric breakdown occurs due to poor withstand voltage of the X-ray tube, and discharge occurs.

If this discharge occurs frequently in the aging process, the X-ray tube is seriously damaged, and there is a risk of being damaged. Further, there is a possibility that the manufacturing apparatus may be broken down.
For this reason, a method is generally used in which the tube voltage is gradually increased so that discharge of extremely large energy does not occur.

However, when discharge occurs, a large amount of energy is momentarily applied to the anode surface, and as a result,
The temperature of the discharge generating part becomes high, and a gas inside the metal is released into the tube. Also, when the minute projections on the anode surface evaporate with the discharge energy, the evaporating gas is released into the tube.

[0013] These gases are finally adsorbed by a getter installed in the tube, and the degree of vacuum in the tube is maintained at a certain level or more, but the gas instantaneously released by the above-described discharge is adsorbed by the getter. It takes some time until it is completed.

Therefore, the degree of vacuum in the X-ray tube is often reduced until the gas instantaneously released by the discharge is adsorbed by the getter, so that the discharge is more likely to occur than in the normal state. .

For this reason, even if the output of the tube voltage control power supply 6 is cut off based on the magnitude of the tube current, if the degree of vacuum in the X-ray tube is reduced, the tube voltage control power supply 6 When the output is connected again, the discharge often occurs successively, and there is a problem that the X-ray tube or the X-ray tube manufacturing apparatus is damaged.

An object of the present invention is to provide a method of manufacturing an X-ray tube capable of suppressing the occurrence of an undesired discharge, reducing damage to the X-ray tube, and hardly causing damage to the X-ray tube manufacturing apparatus body. Is to provide.

[0017]

SUMMARY OF THE INVENTION The present invention has been made based on the above-mentioned problems, and heats a cathode filament by energizing a cathode filament while applying a high voltage called a tube voltage to an anode and a cathode of an X-ray tube. Exhaust that emits anode gas by heating the anode with the energy at which the electron beam collides with the anode, and aging that adjusts the surface state of the anode by colliding the electron beam with the anode or withstand voltage of the X-ray tube In a test or the like for confirming, when returning the tube voltage cut off at the time of the occurrence of discharge, the value of the tube voltage is reduced by a fixed ratio from the voltage before the occurrence of the discharge, and then the filament that flows by supplying electricity to the cathode filament Confirm that the tube current value flowing from the cathode to the anode is not smaller than the current value before the discharge occurs, and return the tube voltage value to the set value. Which is a method for producing X-ray tube according to claim.

Further, according to the present invention, while applying a high voltage called a tube voltage to an anode and a cathode of an X-ray tube, the cathode filament is heated by energizing and heating the cathode filament by an energy which collides with the anode. The tube voltage that was cut off at the time of discharge was restored in exhaust that releases the gas from the anode, aging that adjusts the surface condition of the anode by colliding an electron beam with the anode, or a test that confirms the withstand voltage of the X-ray tube. At the time of the discharge, the value of the tube voltage is reduced by a fixed ratio from the voltage before the occurrence of discharge, and then the tube current value flowing from the cathode to the anode with respect to the filament current value flowing by energizing the cathode filament. A method of manufacturing an X-ray tube, characterized in that the tube voltage value is returned to a set value only when the discharge voltage is not less than before the occurrence of the discharge.

Further, according to the present invention, the anode and the cathode of an X-ray tube are heated by energizing and heating a cathode filament while applying a high voltage called a tube voltage to the anode and heating the anode with energy at which the electron beam collides with the anode. The tube voltage that was cut off at the time of discharge was restored in exhaust that releases the gas from the anode, aging that adjusts the surface condition of the anode by colliding an electron beam with the anode, or a test that confirms the withstand voltage of the X-ray tube. At the time of the discharge, the value of the tube voltage is reduced by a fixed ratio from the voltage before the occurrence of discharge, and then the tube current value flowing from the cathode to the anode with respect to the filament current value flowing by energizing the cathode filament. A method of manufacturing an X-ray tube, comprising returning the tube voltage value to a set value when the magnitude is within a predetermined range before the occurrence of the discharge. .

That is, in the discharge, aging or withstand voltage test of the X-ray tube, when a discharge occurs, a tube current flows between the anode and the cathode of the X-ray tube. The applied tube voltage is cut off, then a tube voltage lower than the tube voltage at which the discharge occurred is applied, and when the magnitude of the tube current is smaller than a predetermined value, the degree of vacuum in the X-ray tube is reduced. After confirming that the X-ray tube has not dropped, by applying a predetermined tube voltage continuously, damage to the X-ray tube can be reduced and damage to the X-ray tube manufacturing apparatus body can be prevented.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an X-ray tube manufacturing apparatus, in particular, an X-ray tube used for aging of the anode of the X-ray tube after vacuum suction and sealing, exhaust of gas in the X-ray tube, or high voltage withstand test of the X-ray tube. It is the schematic which shows an example of the manufacturing apparatus of a wire tube.

In the X-ray tube manufacturing apparatus shown in FIG.
First, a predetermined filament current (arrow) 5 is supplied from a filament power supply 4 to the cathode filament 2 of the X-ray tube 1 whose inside is maintained at a high vacuum, and the cathode filament 2 is heated by the filament current.

In this state, a predetermined voltage is applied between the anode 3 and the cathode (cathode filament) 2 by the high-voltage transformer 7 connected to the tube voltage control power supply 6 so that the anode 3 becomes positive (positive) in potential. Is applied.

As a result, an electron beam E proportional to the temperature of the cathode filament 2 is generated from the cathode 2 and collides with the anode 3. Therefore, a tube current (arrow) 9 flows in the circuit in a direction opposite to the electron beam E.

The magnitude of the electron beam E is controlled by feeding back the magnitude of the tube current 9. That is,
When the tube current 9 flows through the resistor 10, a voltage (arrow) 11 is generated across the resistor 10. Since this voltage usually has a ripple, it is converted by the converter 12 into a complete DC.

The converted DC signal (arrow) 13 is used as a CPU (main controller) 14 for controlling the entire X-ray tube manufacturing apparatus.
Is input to The CPU 14 controls the output of the filament power supply 4 so that the DC signal becomes equal to the set value.

The CPU 14 outputs a control signal (arrow) 15 to the tube voltage control power supply 6 and
Is controlled to be a set value. In this way,
In the X-ray tube manufacturing apparatus, the magnitude of the tube voltage applied between the anode and the cathode filament and the magnitude of the tube current flowing between the two electrodes due to the tube voltage are connected to the internal memory or CPU of the CPU 14 in advance. The size is controlled so as to be the size stored in the memory.

Next, the control timing of the filament current and the tube voltage to the X-ray tube and the change in the tube current in the X-ray tube manufacturing apparatus shown in FIG. 1 will be described. As shown in FIG. 2, while applying a predetermined tube voltage and feeding back the tube current value, the magnitude of the filament current is gradually increased (A).

When the tube current reaches the set value, the magnitude of the filament current is corrected within a range where the tube current is stabilized.
At this time, the filament current value If with respect to the tube current value Ip
Is measured and calculated by K = Ip / If (a) (B).

When a discharge occurs and is detected, the CP
Under the control of U14, the output from the tube voltage control power supply 6 and the high voltage transformer 7 is stopped and the tube voltage is cut off, so that the tube current becomes "0". Becomes constant current control (C).

After a certain period of time has elapsed since the application of the tube voltage was stopped due to the occurrence of discharge, the tube voltage is applied again.
At this time, the magnitude of the tube voltage is controlled by the CPU 14,
(D) and (E) are set at a fixed rate lower than before discharge. Here, at the same time, the filament current is used as feedback control for the tube current. The tube current flows when the tube voltage is applied.However, if the degree of vacuum in the tube is reduced due to the occurrence of discharge, the emission of the tube becomes low. With the magnitude, the set tube current cannot be obtained. For this reason, the magnitude of the filament current is increased (D).

On the other hand, a predetermined time has passed since the occurrence of the discharge,
When the gas in the tube is adsorbed by the getter and the emission of the tube recovers, the tube current gradually increases.In order to bring the tube current closer to a predetermined value, the magnitude of the filament current is increased before discharge occurs. It is progressively reduced (E) to correspond to

Next, the ratio K (formula (a)) of the filament current to the tube current is calculated again, and the point in time at which the value approaches the value calculated before the discharge or within a certain range is determined by CP.
At the time point detected by U14, it is determined by the CPU 14 that the degree of vacuum in the tube has been restored, and the tube voltage, that is, the input voltage supplied from the tube voltage control power supply 6 to the high-voltage transformer 7 is increased to a set value. Is increased to the set value (F).

Thereafter, when a discharge occurs, (D),
Steps (E) and (F) are repeated. As described above, in the evacuation, aging or withstand voltage test of the X-ray tube, when a discharge occurs, a voltage is applied between the anode and the cathode to generate a tube current flowing between the anode and the cathode of the X-ray tube. Then, apply a tube voltage lower than the tube voltage at which discharge occurred, and detect that the magnitude of the tube current is smaller than the predetermined value. After confirming that the X-ray tube has not decreased, the application of the next tube voltage can be started to reduce the damage to the X-ray tube and prevent the X-ray tube manufacturing apparatus from being damaged.

[0035]

As described above, according to the present invention, when discharge occurs in the evacuation, aging or withstand voltage test in the manufacturing process of the X-ray tube, the application of the tube voltage is stopped. The tube voltage is applied again, and the magnitude of the applied tube voltage is set to a magnitude lower by a predetermined ratio than the tube voltage before the discharge occurs. That is, the tube voltage applied again after the discharge occurs is set so that the tube current is smaller than before the discharge occurs. Here, when the magnitude of the tube current depending on the applied tube voltage after the discharge occurs is smaller than the magnitude of the tube current before the discharge occurs or becomes smaller than a predetermined magnitude, The magnitude of the tube voltage is returned to the set value.

As a result, a gas is generated in the interior due to the discharge, and the degree of vacuum in the tube is reduced. In the X-ray tube in a state where discharge is easier than usual, unnecessary discharge continues to occur. Can be prevented, and damage to the X-ray tube and the X-ray tube manufacturing apparatus can be minimized.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for manufacturing an X-ray tube according to an embodiment of the present invention.

FIG. 2 is a voltage and current displacement diagram showing the operation of the X-ray tube shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... X-ray tube, 2 ... Cathode filament, 3 ... Anode, 4 ... Filament power supply, 5 ... Filament current, 6 ... Tube voltage control power supply, 7 ... High voltage transformer, 8 ... Tube voltage, 9 ... Tube current, 10 ... 11: tube current signal voltage; 12: DC converter; 13: tube current signal; 14: CPU; 15: tube voltage control power control signal; 16: filament power control signal.

Claims (3)

[Claims] 1. An anode which is heated by energizing and heating a cathode filament while applying a high voltage called a tube voltage to an anode and a cathode of an X-ray tube. When the tube voltage that was cut off at the time of discharge was restored in the aging that adjusts the surface condition of the anode by colliding the electron beam with the anode or the test to check the withstand voltage of the X-ray tube, etc. The value of the tube voltage is reduced by a fixed ratio from the voltage before the occurrence of the discharge, and the tube current value flowing from the cathode to the anode with respect to the filament current value flowing when the cathode filament is energized is changed by the discharge generation. A method for manufacturing an X-ray tube, comprising: confirming that the tube voltage value is not less than before, and returning the tube voltage value to a set value. 2. A method in which a high voltage called a tube voltage is applied to an anode and a cathode of an X-ray tube while the cathode filament is energized and heated to generate an electron beam. When the tube voltage that was cut off at the time of discharge was restored in the aging that adjusts the surface condition of the anode by colliding the electron beam with the anode or the test to check the withstand voltage of the X-ray tube, etc. The value of the tube voltage is reduced by a fixed ratio from the voltage before the occurrence of the discharge, and the tube current value flowing from the cathode to the anode with respect to the filament current value flowing when the cathode filament is energized is changed by the discharge generation. A method of manufacturing an X-ray tube, wherein the tube voltage value is returned to a set value only when not less than before. 3. An anode which is heated by energizing and heating a cathode filament while applying a high voltage called a tube voltage to an anode and a cathode of an X-ray tube. When the tube voltage that was cut off at the time of discharge was restored in the aging that adjusts the surface condition of the anode by colliding the electron beam with the anode or the test to check the withstand voltage of the X-ray tube, etc. The value of the tube voltage is reduced by a fixed ratio from the voltage before the occurrence of the discharge, and the tube current value flowing from the cathode to the anode with respect to the filament current value flowing when the cathode filament is energized is changed by the discharge generation. A method for manufacturing an X-ray tube, wherein the tube voltage value is returned to a set value when the size is within a predetermined range as compared with the previous case.