JPH01217831A - Automatic ageing device for open type x-ray tube - Google Patents

Abstract

PURPOSE:To carry out the automatic ageing of an X-ray tube by detecting the vacuum pressure of the X-ray tube, and controlling the load of the X-ray tube by a control device. CONSTITUTION:The degree of vacuum of an X-ray tube is detected by a vacuum gauge 24 and the signal is input to a control device 32. Inside an X-ray tube, the inner pressure is raised suddenly after the ageing is started, and then dropped to a specific standard pressure. The control device 32 has a specific standard pressure deciding means 40, a pressure rising speed deciding means 42, a watching pressure deciding means 44, a rising time deciding means 46, and a restoration time deciding means 48, and the detected output of the vacuum gauge 24 is given to the means 42, 46, and 48. The outputs of these deciding means are given to a control means 50 to control a high voltage power source 26, the tube voltage E and the tube current I are controlled according to the program of the control device, depending on the time (t) and the change of the inner pressure P, and the ageing is carried out. By such a constitution, the X-ray tube can be aged automatically without disturbing the worker's hand.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic aging device for releasing gases adsorbed on a target of an open X-ray tube.

[Prior art] Open-type X-ray tubes have the advantage of allowing the vacuum chamber to be exposed to the atmosphere and replacing the target and electron gun filament, but after the vacuum chamber is evacuated and returned to vacuum, the Before use, it is necessary to release the adsorbed gas from the target. This gas release operation is called aging.

In the conventional aging method, an operator gradually increases the tube voltage and tube current of the X-ray tube according to a predetermined procedure. In other words, if a specified load is applied to the X-ray tube for a certain period of time, the load is increased and the
This involves applying a load to the X-ray tube, and this process is repeated until the tube reaches its maximum load.

At that time, aging is performed while monitoring the pressure inside the vacuum container of the X-ray tube with a vacuum gauge, and the
If so, we are taking measures such as reducing the load.

[Problems to be Solved by the Invention] In the conventional aging method described above, an operator must constantly attend to and operate the high-voltage power source of the X-ray tube. Moreover, it is a troublesome task to increase the tube voltage and tube current of the X-ray tube while appropriately suppressing gas release from the target.

In view of the above points, the object of the present invention is to create an open type x1 system without bothering the operator! An object of the present invention is to provide an automatic aging device that can automatically age pipes.

[Means for Solving the Problems] In order to achieve the above object, an automatic aging device according to the present invention has the following components.

(a) A vacuum gauge that detects the pressure inside the vacuum container of the X-ray tube.

(b) A control device that gives instructions for tube voltage and tube current to the high-voltage power source of the X-ray tube according to a predetermined procedure based on the pressure detected by the vacuum gauge.

If this automatic aging device is made more concrete, it can have the following components.

(a) A vacuum gauge that detects the pressure inside the vacuum container of the X-ray tube.

(b) A timer that outputs the passage of time.

(c) Reference pressure determining means is connected to the vacuum gauge and generates an output signal when the detected pressure falls below a predetermined reference pressure.

(d) Pressure increase speed determination means, which is connected to the vacuum gauge and the timer and generates an output signal when the detected pressure increase rate exceeds a predetermined limit speed.

(e) Monitoring pressure determining means that is connected to the vacuum gauge and generates an output signal when the detected pressure exceeds a predetermined monitoring pressure.

(f) when the rising time from the time when the load on the X-ray tube is increased to the time when the detected pressure reaches its maximum value by being connected to the vacuum gauge and the timer exceeds a predetermined first time limit; Rise time determination means for generating an output signal.

rQ) Connected to the vacuum gauge and the timer, if the restoration time from the time when the load on the X-ray tube is increased to the time when the detected pressure falls below the reference pressure again exceeds a predetermined second time limit. , restoration time determining means for generating an output signal.

(h) outputting a command to increase the load on the X-ray tube when receiving an output signal from the reference pressure determining means; Control means outputs a command to reduce the load on the X-ray tube when receiving an output signal from any means of the restoration time determination means.

[Function] In this automatic aging device, the pressure inside the vacuum container of the X-ray tube is detected by a vacuum gauge, and the tube voltage and tube current of the X-ray tube are controlled based on the detected pressure. That is, the load on the X-ray tube is increased step by step according to a predetermined procedure stored in the control device. At that time, it is determined when to increase or decrease the load based on the detected pressure.

Thereby, the aging of the X-ray tube can be automated without bothering the operator.

More specifically, the following five criteria can be used to appropriately increase or decrease the load on the X-ray tube. In other words, (a) Has the detected pressure fallen below a predetermined reference pressure?

(b) Did the rate of increase in detected pressure exceed a predetermined speed limit?

(c) Did the detected pressure exceed the predetermined monitoring pressure?

(d) Whether the rise time from the time when the load on the X-ray tube is increased to the time when the detected pressure reaches its maximum value exceeds the predetermined first time limit.

(e) Whether the restoration time from the time when the load on the X-ray tube was increased until the time when the detected pressure falls below the reference pressure again exceeds the predetermined second time limit.

By providing each means for executing the above five determinations in the control device, the load on the X-ray tube can be increased appropriately.

[Example] Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

An electron gun 14 and a target 16 are installed inside the vacuum vessel 12 of the X-ray tube 10. A turbo molecular pump 20 is connected to the vacuum vessel 12 via a gate valve 18, and an oil rotary vacuum pump 2 is connected to the turbo molecular pump 20.
2 are connected.

A hot cathode ionization vacuum gauge 24 is roughly connected to the vacuum container] 2.

A high voltage power supply 26 is connected to the electron gun 14, and this high voltage power supply 26 is connected to a high voltage generating section 28 and a high voltage! l1fJ control section 30. A wJ control device 32 is connected to the high voltage control section 30. The vacuum gauge 24 is connected to the control device 32 via an A-D converter 34.

A timer 36 is generally connected to the control device 32 . Turbo molecular pump 20 and oil rotary vacuum pump 22
is driven and controlled by an exhaust controller 238, and the exhaust controller 38 is roughly connected to the control device 32.

Although the exhaust controller 38 does not receive commands from the control device 32 during the automatic aging operation, it can also command the operation of the exhaust system on the control device 32.

FIG. 2 is a block diagram showing the configuration of the control device 32. As shown in FIG. The control device 32 includes five determination means. That is, reference pressure determination means 40, pressure increase rate determination means 42, monitoring pressure determination means 44, and rise time determination means 4
6. Restoration time determination means 48. The output of the vacuum gauge 24 is input to these five determination means. Further, the output of the timer 36 is inputted to three determining means that use the passage of time as a determining factor, namely, a pressure increase rate determining means 42, a rising time determining means 46, and a restoring time determining means 48. All the outputs of the five determination means are input to the control means 50, and the output becomes a command signal for the high voltage electric m26.

Next, the operation of this embodiment will be explained. In Figure 1,
Assume that the vacuum vessel 12 of the X-ray tube 10 is vented to atmosphere and, for example, the target 16 is replaced. Thereafter, the vacuum container 12 is evacuated to a predetermined pressure by the turbo molecular pump 20. Next, the knee jerk start button of the control device 32 is pressed to start automatic aging of the X-ray tube 10.

FIG. 3 is a graph showing the pressure P in the vacuum vessel 12, the tube voltage E, and the tube current I of the X-ray tube over time during automatic aging. Time t.

When aging starts, the tube voltage E=20 kV and the tube current I=10 mA are initially set.

As the electron beam collides with the target, gas is naturally released from the target, causing a sudden increase in pressure. However, the pressure eventually begins to fall and reaches a predetermined reference pressure of 1O-
The pressure drops to 4Pa (Pascal) (-A point, time t
1〉. Then, an output signal is output from the reference pressure determining means 40 shown in FIG. 2 and sent to the control means 50. In response to this, the control means 50 instructs the high voltage power supply 26 to increase the load.

In this embodiment, the first stage load increase is implemented in the following procedure. First, at time t1, E is set to 22 kV, and then I is set to 20 mA.

In that order, E=24kV, I=40mA, E=26
kV, I = 60mA, the tube voltage E is increased by 2kV, the tube current I is increased by 20mA, and finally E = 30k.
V, I=100mA1. :HU is set. With the above, the first
Phase load increase is completed.

When the load increases, the pressure increases, then decreases again to the reference pressure of 10'Pa (point 8, time tz). Then, the load is increased in the same way as at time t1. That is, the load is alternately increased by E=2 kV and ■=20 mA, and finally E=40 kV and I-1-2O0. This completes the second stage of load increase.

When the pressure rises and falls and reaches the reference pressure again (
0 point, time t3), the third stage of load increase is implemented. At this point, the tube current has already reached a maximum current of 200mA.
If the tube voltage is increased as it is, the load will become too large. Therefore, to avoid this, first lower the tube current from 200mA to 100mA. Then, the tube voltage is increased to 50 kV, and then the tube current is increased by 20 mA. Finally, E=50kV,
I = 200mA. This completes the third stage of load increase.

When the pressure rises and falls and reaches the reference pressure again (
0 point, time t4), the final stage of load increase is implemented. This increase is carried out similarly to the third stage load increase, resulting in E=60kV and I=200mA.

When the pressure rises and falls and reaches the reference pressure again (
At point E, time t5), aging ends and the tube voltage and tube current are returned to zero.

The load increase procedure as described above is stored in advance in the control device, but various parameters can also be changed externally. That is, in Fig. 3, the tube voltages are 20kV, 30kV, and 40kV.
V,! :, 10kV'f"), but with this you can also set it finely. Roughly, 20kV'f")
When increasing from V to 30kV, in Figure 3, 2
Although it is gradually increased in kV increments, the increments can also be set to other values. Regarding the tube current, settings and increments different from those shown in FIG. 3 can also be adopted.

In order to clarify the procedure for increasing the load, the above explanation is based on the criteria for increasing and decreasing the load.
An example is shown in which only the reference pressure determination means 40 in FIG. 2 is functioning. The determination based on this reference pressure is the most basic determination for automatic aging, and this is the only determination criterion for increasing the load. The remaining four criteria all come into play when there is too much outgassing. If too much gas is released, unstable phenomena such as electrical discharge are likely to occur within the X-ray tube, and too much load will be placed on the exhaust system, so it is necessary to reduce the load.

FIG. 4 is a pressure-time graph illustrating these remaining four criteria. When the pressure falls to the reference pressure P1 (1 point), the load on the X-ray tube is increased and the pressure rises.

The rate of increase in pressure at this time is, for example, the value obtained by dividing the amount of pressure increase ΔP from point 8 to point 2 by the elapsed time Δt (
ΔP/Δt). Actually, inside the control device, the above-mentioned rising speed is determined every moment at shorter time intervals than shown in FIG. The elapsed time Δt can be determined by counting the clock signal from the timer 36. The resulting rate of pressure rise is compared with a predetermined limit rate, and if it is greater than the predetermined limit rate, it is determined that too much gas is released and the load on the x-ray tube is reduced.

Such an operation is carried out by the pressure increase rate determining means 42 in FIG.
and the subsequent control means 50.

Returning to FIG. 4, the pressure reaches its maximum value at point G.

If the pressure reaches the monitoring pressure P2 before reaching the maximum value, the monitoring pressure determining means 44 will function, determining that too much gas is being released, and the load will be lowered.

When the elapsed time from 1 point to the local maximum value 0 point, that is, the pressure rise time T1, exceeds a predetermined first time limit, the rise time determination means 46 functions, and it is determined that the gas release is not slowing down, The load is reduced. The first time limit can be set in advance using the timer 36.

As the pressure continues to fall, it will again drop below the reference pressure at point H. Now the load increase is implemented again. However, if the elapsed time from point F to point H, that is, the restoration time T2, exceeds the predetermined second time limit, the restoration time determination means 46 functions and determines that the gas release is not slowing down. , the load is lowered. Actually, before reaching point H, the restoration time determination means 46 functions at the time when the elapsed time from point F exceeds the second time limit. The second time limit can also be set in advance using the timer 36.

When lowering the load, the load may be returned to the previous level, or may be returned to an intermediate value between the previous level and the current load.

The operations described above can be summarized as shown in the flowchart of FIG. The aging example shown in the graph of FIG. 3 is shown in FIG.
and a step in which the reference pressure determination means functions and the load is increased step by step (repetition of steps 54, 56, and 58), and finally, the load is released (step 60) and the automatic Aging ends. Steps 62-7
0 is the procedure when the load is lowered due to excessive gas release.

[Effects of the Invention] As explained above, the present invention detects the pressure inside the vacuum container of the X-ray tube with a vacuum gauge, and controls the tube voltage and tube current of the X-ray tube based on the detected pressure. This makes it possible to automatically age the X-ray tube without bothering the operator.

Further, in the invention of claim 2, five criteria are used to determine whether the load is increased or decreased. Therefore, especially when too much gas is released, the phenomenon can be determined from multiple perspectives, the load can be appropriately reduced, and unstable phenomena such as discharge can be avoided in advance.

With conventional manual aging, it is completely impossible to make judgments from such multiple perspectives.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of the control device, Fig. 3 is a graph showing the time course of pressure and load, and Fig. 4 shows various judgment criteria. An illustrative pressure-time graph is shown in FIG. 5, which is a flowchart of this embodiment. 10...X-ray tube 12...Vacuum container 24...Vacuum gauge 26...High voltage power supply 32...Control device 36...Timer 40...Reference pressure determination means 42...Pressure increase Speed determination means 44...Monitoring pressure determination means 46...Rise time determination means 48...Restoration time determination means 50...Control means

Claims (2)

[Claims] (1) An automatic aging device for open X-ray tubes having the following components: (a) A vacuum gauge that detects the pressure inside the vacuum container of the X-ray tube. (b) A control device that gives instructions for tube voltage and tube current to the high-voltage power source of the X-ray tube according to a predetermined procedure based on the pressure detected by the vacuum gauge. (2) An automatic aging device for open X-ray tubes having the following components: (a) A vacuum gauge that detects the pressure inside the vacuum container of the X-ray tube. (b) A timer that outputs the passage of time. (c) Reference pressure determining means connected to the vacuum gauge and generating an output signal when the detected pressure falls below a predetermined reference pressure. (d) Pressure increase speed determination means, which is connected to the vacuum gauge and the timer and generates an output signal when the detected pressure increase rate exceeds a predetermined limit speed. (e) Monitoring pressure determining means that is connected to the vacuum gauge and generates an output signal when the detected pressure exceeds a predetermined monitoring pressure. (f) when the rising time from the time when the load on the X-ray tube is increased to the time when the detected pressure reaches its maximum value by being connected to the vacuum gauge and the timer exceeds a predetermined first time limit; Rise time determination means for generating an output signal. (g) connected to the vacuum gauge and the timer, so that the restoration time from the time when the load on the X-ray tube is increased to the time when the detected pressure falls below the reference pressure again exceeds a predetermined second time limit; and a restoration time determining means that generates an output signal. (h) outputting a command to increase the load on the X-ray tube when receiving an output signal from the reference pressure determining means; Control means outputs a command to reduce the load on the X-ray tube when receiving an output signal from any means of the restoration time determination means.