JPH04359851A - X-ray tube device with rotary anode - Google Patents

Abstract

PURPOSE:To predict failure through monitoring of the performance of a ball bearing in an X-ray tube, and thereby prevent interruption of photographing due to sudden occurrence of failure in an X-ray device with rotary anode. CONSTITUTION:A vibratory acceleration sensor 15 is installed on a tube support 14 or envelope 9 of an X-ray tube device with rotary anode, and signals therefrom are amplified by an electric charge amplifier 16 and separated by a filter 17 into high frequency components and low frequency component. The low frequency components are converted by a frequency-voltage converter 18 into a voltage to indicate the revolving speed and by an AC/DC converter into a voltage to exhibit the amount of unbalance, while the high frequency components are converted by AC/DC converter into a voltage to show the coarse loss of a ball bearing, and a relay switch judges whether the current situation is normal or abnormal. Thereby the frictional torque of X-ray tube, amount of unbalance, and coarse loss of bearing can be known on real time basis, which should contribute to prevention of trouble in advance, and also the X-ray tube replacing timing can be set well scheduled.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a rotating anode X-ray tube device in which a target and anode assembly are supported by ball bearings and rotate at high speed, and is particularly used in a large system such as an X-ray CT device. This invention relates to a rotating anode X-ray tube device in which it is desired to know in advance when to replace it due to its lifespan, and in which a fast start-up characteristic of the rotational speed is required.

0002

2. Description of the Related Art A rotating anode X-ray tube device rotates an anode target in order to prevent the focal portion of the anode target from being melted by high-speed electrons from the cathode.
A cathode, a rotating anode, and a rotor connected to the rotating anode are placed in a vacuum envelope made of glass or the like, and a stator coil is placed outside the vacuum envelope to rotate the rotor to generate the rotating anode. It is configured to rotate.

[0003] The allowable load rating of this X-ray tube (X-ray tube voltage K
V, X-ray tube current mA, and load application time sec) are determined by the rotational speed, and in order to prevent accidents such as destruction, various methods have been proposed to control the rotational speed by detecting and feeding back the rotational speed. For example, a photoelectric rotation detector is installed outside the envelope of the X-ray tube apparatus to detect the rotation of the anode by transmitting or reflecting light. However, with this method, the photoelectric rotation detector must be placed close to the high voltage side, which is dangerous, and there are problems such as complicated positioning and space problems.Also, due to deterioration of the cooling oil, reflected light or transmitted light There is a problem with light attenuation, so it has to be said that it is practically impossible.

[0004] Furthermore, Japanese Utility Model Publication No. 1-24880 proposes a method of detecting the voltage generated in the main coil and the auxiliary coil of the stator coil and comparing it with a reference voltage to detect the rotation speed. However, this method has the disadvantage that the rotation speed detection accuracy is insufficient and detailed feedback of the rotation speed cannot be provided.

On the other hand, conventional abnormality determination devices due to mechanical damage to rolling bearings detect periodicity caused by damage to bearings, as described in Japanese Patent Laid-Open Nos. 51-136465 and 53-9584. Moreover, the pulse-like high impact acceleration is detected by a vibration acceleration detector, and compared with the judgment standard value according to the separately detected rotation speed information, and the abnormality period is determined based on the rate of increase in the magnitude of the impact acceleration over time. was beginning to be predicted. Therefore, this method requires two pieces of detection information: the vibration acceleration of the bearing and the rotational speed of the shaft, and since it is difficult to detect the rotational speed in the X-ray tube as mentioned above, this method can prevent damage to the bearing of the X-ray tube. It was not possible to determine an abnormality.

[0006] The present inventors also installed a rotation speed detection device using a capacitive displacement meter in the X-ray tube, and detected the ratio of change in rotation speed with respect to time change during inertial rotation of the shaft. In Japanese Patent Application No. 100987/1987, a method was proposed in which the degree of abnormality in the bearing is determined by converting the friction torque into the friction torque of the bearing based on the value, and then comparing this friction torque with a determination reference value. However, this method also requires the detection of rotational speed, and the mounting position of the capacitance displacement meter may be subject to high voltage, so detection of rotational speed has been a hurdle in the practical application of this method.

[0007]

As is well known, a rotating anode X-ray tube device is an X-ray source for an X-ray CT apparatus. Furthermore, recent advances in medical technology in circulatory diagnosis have been remarkable, and tests and treatments are now performed while observing X-ray images. Therefore, higher reliability is required of X-ray tubes than ever before. However, an X-ray tube is a type of electron tube and is a consumable item with a limited lifespan. All medical diagnostic equipment requires high reliability because human life is involved, but in particular, since X-ray tubes are considered consumables, it is desirable to be able to predict in advance when they will need to be replaced. X-ray CT equipment is an extremely complex mechanism, and it takes a long time to remove and install the X-ray tube.
Alternatively, it can be replaced when it does not interfere with diagnostic work, such as on holidays.

[0008] Failure of an X-ray tube is caused by (1) a decrease in withstand voltage performance;
It is no exaggeration to say that (2) the problems are all about poor rotational performance. Decrease in voltage resistance performance is often caused by bearings. That is, as damage to the bearing progresses and wear particles are generated, the electric field distribution is disturbed and the withstand voltage performance is reduced. Furthermore, when the friction torque increases, the rotational speed decreases, and the heat load on the anode target becomes excessive, causing local temperature rise. The anode target is
Due to the excessive temperature rise, gas is released, resulting in a decrease in withstand voltage performance.

[0009] In addition, poor rotational performance can be caused by an increase in noise due to the progress of bearing damage, or by excessive unbalance due to deformation of the rotating body. Regarding friction torque (
1) As already mentioned in relation to the decrease in withstand voltage performance.

In short, if the rotational performance of the bearing, that is, the friction torque and vibration acceleration, are known, the lifespan or failure of the X-ray tube can be predicted, and the friction torque can be determined by detecting the rotational speed.

[0011] The present invention predicts the failure and lifespan of the X-ray tube in advance, prevents interruption of diagnosis due to sudden failure of the X-ray tube,
The aim is to keep the patient's suffering to a minimum and ultimately save lives.

0012

[Means for Solving the Problem] In order to achieve the above object, a vibration acceleration sensor is attached to a tube support or a position close to the tube support of a sealed container, and the acceleration signal from the sensor is filtered through a low-pass filter and a high-pass filter. The signal is separated into low-frequency components and high-frequency components, and amplified by an amplifier. The position where the vibration acceleration sensor is installed is insulated from the stator coil support with rubber or the like so that it is not subjected to vibration due to the electromagnetic force of the stator coil.

The low frequency component consisting of the rotational component is input into a frequency-voltage converter, and the rotational speed is converted into voltage. An AC-DC converter converts the low-frequency components and high-frequency components into DC voltage according to the vibration intensity.

The output voltage of the low frequency component is compared with a reference value,
It is checked whether a predetermined number of rotations has been reached at a predetermined time or whether there is an abnormal drop in the number of rotations. Multiple reference values are set for high-frequency components, the order of warnings is made more careful, and the time for replacement is announced.

A double integration circuit may be provided to extract the rotational speed component from the vibration acceleration.

[0016]

[Operation] The rotating anode X-ray tube has an anode target of 10-6t.
The anode target rotates in a high vacuum of less than orr, and the bearing portion reaches a high temperature of 400 to 500° C. due to the enormous amount of heat generated in the anode target. Therefore, silver, lead, molybdenum disulfide (MoS)
2) Solid lubrication is used, but solid lubrication has the disadvantages of unstable friction torque, high noise, and short life. In order to monitor the above basic rotational performance, we conducted various tests and analyzed the data, and as a result, we determined that information based on vibration acceleration is most suitable for monitoring.

Typical vibrations that can be easily measured are vibration displacement and acceleration, and the second-order differentiation of displacement gives acceleration, which is expressed by the following equation. Letting the vibration displacement be a and the vibration acceleration α, where A: constant, π: pi, f: vibration frequency, t:
time

As can be seen from Equation 2, the vibration acceleration α increases as the frequency increases, that is, as f increases, and high-frequency vibrations that cannot be measured by displacement can be measured by acceleration. When the acceleration is double integrated, the displacement is expressed by Equation 1, and the vibration displacement is dominated by the rotational speed component.

Conversely, high-frequency vibration acceleration cannot be detected even if the vibration displacement is measured and second-order differentiated. That is,
This is because the frequency and level displacement amplitudes that are the subject of discussion in terms of acceleration are less than 0.1 μm or less than 0.01 μm and cannot be measured.

[0020] The acceleration sensor attached to the tube support or near the tube support outputs vibration acceleration ranging from the rotational speed component to 20 KHz in the audible frequency band. If this is amplified and a high frequency component of 1 KHz or more and a rotational speed component are extracted, damage to the bearing can be determined from the high frequency component, and the rotational speed can be determined from the rotational speed component.

[0021] Furthermore, vibration acceleration is an elastic wave propagating through a solid body. Therefore, vibrations can be detected by the acceleration sensor even if a solid material such as a polymer resin or ceramic with high electrical insulation is placed between the propagation paths. This point is extremely important in a rotating anode X-ray tube device. This is because high voltages of several tens of kilovolts tend to be applied to members surrounding the rotating body. Therefore, it is impossible to attach a sensor to the rotating body and the metal members surrounding it, and it is also impossible to get close to it. However, if acceleration is to be detected, it can be measured using solid propagation.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a rotating anode X-ray tube device according to the present invention. The rotating anode X-ray tube device includes a cathode 2 that generates thermionic electrons in a vacuum envelope 8 made of glass or metal, and an anode target 1 that generates X-rays by receiving thermionic electrons.
, a rotor 3 that rotates the anode target 1, a ball bearing 5 that is attached to the rotating shaft 4 and rotatably supports the rotor 3, and a housing 6 that houses the ball bearing 5 in a high vacuum state within the vacuum envelope 8. It is enclosed in. The above structure is called a rotating anode X-ray tube (hereinafter referred to as an X-ray tube). A stator 7 is provided on the outer periphery of the vacuum envelope 8 , and the stator 7 is attached to a frame 12 . A tube support 14 is fixed to the frame 12, and the X-ray tube is fixed at the center of the tube support 14. The X-ray tube and frame 12 are housed in an envelope 9 called a Haube, and insulating oil 11 is sealed in the envelope 9 for cooling and electrical insulation. The cathode side of the X-ray tube is supported by an envelope 9 via a rubber chip 10. 13a and 13b are bushings that supply high voltage to the cathode 2 and anode (anode target 1, rotor 3, rotating shaft 4, bearing 5, housing 6). Piezoelectric vibration acceleration sensor 1
5 is fixed to the tube support 14 with screws and adhesive. A charge amplifier 16, a filter 17, a frequency-voltage converter 18, AC-DC converters 19, 20, and relay switches 21, 22, 23 are provided outside the envelope 9.

In the rotating anode X-ray tube device having the above configuration, when the anode target 1 rotates, a high voltage supplied by the bushings 13a and 13b is applied between the cathode 2 and the anode target 1, and the cathode 2 is connected to the anode target. When an electron beam is emitted onto the anode target 1, X-rays are generated from the surface of the anode target 1 in the direction of the arrow in the figure. At this time, the average temperature of the anode target 1 is approximately 1000°C, and since the inside of the vacuum envelope 8 made of glass or metal is kept airtight at a high vacuum, most of the heat is radiated and transferred to the outside of the vacuum envelope. It gets heated. However, some of the heat from the anode target 1 is transferred to the rotating shaft 4, ball bearing 5, and housing 6 by conduction, and the ball bearing 5 reaches a high temperature of approximately 500°C, so a thin film of lead or silver is applied to the ball. Covered with solid lubrication. The bearing clearance should be 40 to 60 μm (5 to 10 μm for normal electric motors) to take into account the entrapment of solid lubricant film fragments or thermal expansion.
are used.

Conventionally, the thickness of the solid lubricant film is 0.5 to 0.7.
Although the thickness was assumed to be .mu.m, here it is set to 0.2 to 0.4 .mu.m. The reason is as follows.

[0025] A thickness of 0.5 to 0.7 μm had a sufficiently long life, and further rotation was possible even if the amount of X-rays was reduced due to rough damage caused by electron bombardment of the anode target. The X-ray tube ultimately receives the electron beam from the anode target and produces X-rays.
The lifespan is determined by the damage to the focal plane that generates the lines. Improvements have been made in the materials used for anode targets, and the current material, which is a mixture of tungsten and rhenium, is slow to develop roughness. However, if the bearing is used for a long time, the amount of X-rays will decrease, so there is no need to extend the life of the bearing more than necessary.

On the other hand, it is desirable that the solid lubricant film be as thin as possible from the viewpoint of suppressing vibration and noise. As the name suggests, solid lubricants are solids, have a finite size and shape, and cannot maintain the same uniformity as an oil film. For this reason, lubrication is achieved by forming micron-level irregularities on the ball surface or the raceway surfaces of the inner and outer rings. The size of the unevenness increases as the thickness of the lubricant film increases, that is, as the supply amount increases. Since noise and vibration increase with the size of the irregularities on the ball surface and rolling surface, it is desirable that the lubricating film be thin. X-ray tubes are used in quiet environments such as hospitals, and they must be quiet so as not to make patients feel anxious. Furthermore, if the vibration is large, the X-ray source will shake, resulting in a reduction in the quality of the X-ray image.

[0027] For the above reasons, the film thickness is 0.2 to 0.4μ.
m, achieving quietness and low vibration, but the lifespan is now finite instead of the conventional semi-infinite life, which is almost as long as the replacement period due to the decrease in the amount of X-rays. Note that the degree of damage to the target focal plane is determined by the period of use, that is, the number of times of imaging and the intensity of the electron beam. If it is used to emit only weak X-rays, the damage to the anode target will only progress slowly even if it is used many times. On the other hand, the bearing life also largely depends on the electron beam intensity. For solid lubricated ball bearings, the temperature determines the lifespan. That is, when the temperature is high, the hardness of the bearing material decreases, making it more likely to wear, and the lubricant evaporates faster and may disappear. When the intensity of the electron beam to the anode target is strong, the temperature of the anode target increases, and the bearing temperature also increases accordingly. In this way, the intensity of the electron beam to the anode target is a factor that determines the life of the anode target and the bearing.If the electron beam intensity is strong, the damage to the anode target will increase, but the life of the bearing will also be shortened. Therefore, by monitoring the bearing life, the life of the X-ray tube device can be determined.

When the X-ray tube rotates, a high frequency component generated by rolling of the balls of the ball bearing 5 and a rotational speed component generated by an imbalance in the rotation system become vibrations. These vibrations are detected by the acceleration sensor 15, amplified by the charge amplifier 16, and then separated by the filter 17 into low frequency components up to 500 Hz and high frequency components from 800 Hz to 10 KHz. FIG. 2 shows the results of frequency analysis of the vibration signal amplified by the charge amplifier 16. In (a), the rotation is in good condition, and the high frequency components are generally low and quiet. 170Hz
The peak ω is the rotational speed component. (b) shows a level close to the end of life, and the high frequency region of 800 Hz or more is strong. In this state, the noise is loud.

FIG. 3 shows 500 filters separated by filter 17.
In the signal waveform up to Hz, the low frequency component in this range exhibits a substantially sinusoidal wave, which is the rotational speed component. The frequency-voltage converter 18 converts the frequency of the low frequency component of this signal waveform into a voltage, and outputs a voltage according to the frequency. In FIG. 3, the amplitude is proportional to the amount of unbalance of the anode target of the X-ray tube. Since the AC-DC converter 20 outputs a DC voltage proportional to this amplitude, by inputting the signal waveform shown in FIG. 3 to the AC-DC converter 20, the amount of unbalance of the anode target of the X-ray tube can also be determined.

FIG. 4 shows 800H separated by filter 17.
It is a high frequency vibration waveform of z~10KHz, and the amplitude represents the intensity. The AC-DC converter 19 converts this waveform into a DC voltage and outputs a voltage depending on the roughness of the ball surface or rolling surface.

The relay switches 21, 22, and 23 constitute a determiner for determining rotation speed, unbalance, and high frequency components. The rotational performance of a rotating anode X-ray tube requires low friction torque and low vibration and noise. The X-ray tube is driven by energizing the stator 7 with a predetermined frequency and voltage for a fixed period of time to form an induction motor with the rotor 3 within the vacuum envelope 8. Drive frequency,
The voltage and energization time are predetermined and fixed. Therefore, if the friction torque increases for some reason, the number of rotations reached will decrease.

FIG. 5 shows the operating status of the relay switch 21, where range I is normal, range II is caution, and range III is stopped. The reason why there is a normal width in range I is that when the rotor 3 of the X-ray tube is warmed by the heat generated by the anode target, the motor efficiency decreases and the number of rotations reached decreases. Under normal conditions, the rotation speed changes as shown in (a). When large pieces of solid lubricant get caught between the balls and the raceway, the friction torque temporarily increases, as shown in (b).
falls into the caution zone. This caution area does not reach the point where the target focal plane becomes too heated and discharges. If the solid lubricant gets caught in the engine for a while, it will gradually get used to it and become smooth, and the friction torque will return to normal (c).

[0033] On the other hand, even if the running-in rotation is performed, the (
If the reached rotation speed decreases as shown in (d) and enters the operation stop range from the caution range, and the high frequency vibration acceleration increases as described later, it is not due to the solid lubricant being trapped, but due to wear of the material. Therefore, the X-ray tube needs to be replaced. In addition, (e) is a case where an abnormality on the drive power supply side or a layer short in the stator coil occurs, and the vibration acceleration is extremely small because the rotation speed is low. If the power supply system is examined and repaired, it will be possible to play it again.

As described above, in the past, the rotational speed decreased too much, causing focus melting of the anode target during use, or frequent discharge occurred, and then the target was replaced in a hurry, but with the present invention, it is possible to replace the anode target in a planned manner in advance. Can be exchanged. Furthermore, it is possible to prevent accidents that cause pain to the patient, such as having to retake the image due to discharge.

[0035] In the X-ray tube device for diagnosing the cardiovascular system, importance is placed on the characteristics of the rotational speed rise of the anode target 1. This is to capture the moment when the contrast agent flows into the area where it should be imaged, when injecting the contrast agent into a patient's blood vessels and photographing the blood flow.
From that moment on, powerful X-rays are required. In Figure 5 (a), when the rotation speed reaches point S, it is possible to start X-ray irradiation, but
Previously, a timer was used to allow for two or three times as much time. The present invention has improved the start-up characteristics to the limit of the driving capacity of the X-ray tube, and has significantly reduced the waiting time for doctors.

The X-ray tube generates a huge amount of heat at the anode target 1, which is dissipated into the atmosphere by a cooler (not shown). Since there is a limit to the capacity of the cooler, if the amount of heat generated by the stator 7 is large, the amount of heat generated by the anode target 1 is limited accordingly, which lengthens the downtime of the X-ray tube. To prevent this, it is necessary to shorten the time during which the stator 7 is energized. In the present invention, after the maximum rotational speed is reached, the drive power is cut off and the rotation can be performed by inertia. Then, when the rotation speed drops to the S point, the drive is turned on for a short time to accelerate, and then the S point is reached again.
Freeze to a point. In this way, driving power could be significantly reduced.

The output voltage of the AC-DC converter 20 is proportional to the amplitude of the rotational speed component, and as described above, this corresponds to the amount of unbalance. The X-ray tube repeatedly heats and cools rapidly.
Furthermore, the maximum temperature of the anode target 1 may reach 1000°C, the rotor 3 may reach 700°C, and the rotating shaft may reach 500°C. Therefore, misalignment inevitably occurs at the assembly joint due to thermal expansion, resulting in imbalance. The unbalance during high-speed rotation acts in a direction that further increases the unbalance, vibrates the entire X-ray tube apparatus, and causes image disturbance. In the worst case, there is a risk of destroying the X-ray tube. Although various measures are taken to prevent the amount of unbalance from increasing, such as improving assembly precision, thorough balancing, and absorbing vibration energy, unbalance may increase due to unexpected causes. In the present invention, since the amount of unbalance can be monitored using the output voltage of the AC-DC converter 20, the time for replacement can be set in a planned manner using the relay switch 22 when the amount of unbalance increases to a specified range.

As shown in FIG. 6, the output of the high frequency component of the AC-DC converter 19 is classified by the relay switch 23 into I (normal), II (attention), and III (rotation stopped). In solid lubricated ball bearings, even if the lubricant disappears and the material wears, the friction torque does not increase significantly and is often not detected by monitoring the rotational speed as described above. This is because when the material wears uniformly and little by little from the surface, the amount of wear particles is small and large, but even if the wear particles are caught between the ball and the raceway, they are small and will not significantly increase the friction torque. . However, the discharge of wear powder induces electrical discharge, making it impossible to take pictures, so it is necessary to replace the X-ray tube in advance. Fortunately, in order for the abrasion powder to induce discharge, it must come out from the rotor 3 and scatter near the anode target 1 or the cathode 2, and it takes time to reach there. If the output voltage of the high frequency component is monitored, it is possible to replace the battery in a planned manner before frequent discharge occurs as shown in FIG. Figure 6 shows the effective value of the output, in which (a) is a typical example when the lubricant film thickness is 0.25 μm, and (b) is a typical example when the lubricant film thickness is 0.6 μm. The data shows that the results were low.

FIGS. 7 to 9 show another embodiment of the present invention and relate to a method of mounting the acceleration sensor 15. FIG. The vibration energy is attenuated as the mounting position of the acceleration sensor 15 moves away from the tube support 14, and in particular, the higher the frequency component, the greater the attenuation rate. However, since the amplifier of the charge amplifier 16 is sufficiently large, there is no problem in implementing the present invention, and the influence of the high voltage applied to the anode as shown in FIGS. The acceleration sensor 15 may be attached to a position where it can be easily attached without being damaged.

FIG. 9 shows an embodiment of an X-ray tube apparatus in which an X-ray tube is supported in a vibration-isolated manner. It is attached to the tube support 14. The acceleration sensor 15 is fixed to an insulating plate 16 made of highly insulating resin with screws and adhesive. If the driving power supplied to the stator 7 is extremely strong and the stator 7 vibrates at the driving frequency, or if strong vibrations propagate from the medical diagnostic equipment to which the rotating anode X-ray tube device is attached, those vibrations will enter the acceleration sensor 15. There is a risk of causing malfunction. In the embodiment shown in FIG. 9, vibration is insulated by the vibration isolating rubber 14b and the vibration isolating ring 14c, and the influence of external vibration can be reduced to a negligible level.

FIG. 10 shows still another embodiment in which the acceleration sensor 15 is covered with a thin lead plate 15a and a ground wire 15b is provided. The lead plate 15a shields X-rays and prevents drift (a kind of malfunction) of the acceleration sensor 15 due to X-rays, and the ground wire 15b prevents drift due to an electric field. With high performance, large capacity, and powerful rotating anode X-ray tube equipment,
It is necessary to protect the acceleration sensor and prevent drift by shielding it from X-rays and preventing static electricity.

FIG. 11 shows an embodiment in which the filter 17 is replaced by a double integration circuit 17'. Double integration circuit 17'
From the filtered waveform of FIG. 3, a complete sine wave with only the rotational speed component is obtained from the vibration signal that has passed through the filter. The rotational speed component is obtained from the double integration circuit 17', and the high frequency component is sent from the charge amplifier 16 directly to the AC-DC converter 20. 0 to 10
The energy intensity of vibration acceleration over the entire KHz range is 8
High frequency components of 00 Hz or more are dominant, and the presence or absence of vibration components of 500 Hz or less can be ignored when monitoring the rolling state of the ball. Therefore, if the rotational speed component is extracted using a double integration circuit 17' instead of the filter 17, the same effect as in FIG. 1 can be obtained.

[0043]

[Effects of the Invention] As detailed above, according to the present invention, a vibration acceleration sensor is attached to a rotating anode X-ray tube device so that the rotational speed component and high frequency component can be monitored. It is possible to predict and prevent malfunctions caused by short, noisy solid lubricated ball bearings in advance. In other words, if the frictional torque rapidly increases due to the solid lubricant film or large pieces of bearing material getting caught, and the specified rotational speed is not reached, high voltage cannot be applied between the cathode and anode, and the electron beam is applied to the anode target. Prevents excessive temperature rise or melting. After that, you can wait for some time to recover by running it in. Furthermore, if the device does not recover, it will have to be replaced, but at that time, it can be easily and reliably determined what to do based on the information from the acceleration sensor, so maintenance time can be significantly reduced. Since the rotation speed can be monitored in real time, when you want to quickly start up rotation in cardiovascular applications, you can eliminate the unnecessary waiting time required with conventional methods, and reduce the waiting time until the start of imaging by 1/2 to 1/2. It can be shortened to 3. Furthermore, since it is possible to output the vibration amplitude of the rotational speed component that is proportional to the amount of unbalance, it is possible to prevent image quality deterioration and destruction accidents due to increased unbalance in the rotating anode system, and to enable planned replacement.

[0044] In order to extend the life of solid lubricants, it is desirable to increase the thickness of the film, but thickening the film leads to an increase in noise. According to the present invention, even if the lubrication life is designed to be the same as the life of the entire tube, the time for replacement can be known in advance by monitoring high frequency components. In addition, the lubricating film can be made thinner to reduce the lifespan.
Significant noise reduction and stability can be achieved.

The most significant effect is that interruption or failure of diagnosis due to malfunction of the X-ray tube, such as discharge, can be prevented during patient diagnosis.

[Brief explanation of drawings]

FIG. 1 is a sectional view and a block diagram of a rotating anode X-ray tube device to which the present invention is applied.

FIG. 2: Frequency analysis results showing vibration components obtained from an acceleration sensor.

[Figure 3] Vibration waveform of rotational speed component.

FIG. 4: Vibration waveform of high frequency component.

FIG. 5 is a diagram showing the acceleration characteristics and normal/abnormality determination of various X-ray tubes.

FIG. 6 is a diagram showing the transition of high frequency components as the operating time of the X-ray tube passes.

FIG. 7 is a partial cross-sectional view of a rotating anode X-ray tube device showing another example of how to attach an acceleration sensor.

FIG. 8 is a partial sectional view of a rotating anode X-ray tube device showing another example of how to attach an acceleration sensor.

FIG. 9 is a partial cross-sectional view of a rotating anode X-ray tube device showing another embodiment of the method for attaching an acceleration sensor.

FIG. 10 is a partial cross-sectional view of a rotating anode X-ray tube device showing another example of how to attach an acceleration sensor.

FIG. 11 is a block diagram showing another embodiment of the present invention.

[Explanation of symbols]

1 Anode target 2 Cathode 3 Rotor 4 Rotation axis 5 Ball bearing 6 Housing 7 Stator 8 Vacuum envelope 9 Envelope 10 Rubber tip 11 Insulating oil 12 Frame 13a Bushing 13b Bushing 14 Tube support 15 Acceleration sensor 16 Charge amplifier 17 Filter 18 Frequency-voltage converter 19 AC-DC converter 20 AC-DC converter 21 Relay switch 22 Relay switch 23 Relay switch

Claims (4)

[Claims] Claim 1: An anode target disposed facing a cathode, a rotating member integrally formed with the anode target, a bearing device that rotatably supports the rotating member, a part of the bearing device, and a vacuum envelope. A rotating anode X-ray tube with the above-mentioned components covered and evacuated, the rotating anode X-ray tube supported in a sealed container by a tube support, and a rotating magnetic field generated by a rotating member provided on the tube support. A rotating anode X-ray tube device comprising a rotating anode X-ray tube device includes a vibration acceleration sensor mounted on a tube support or a sealed container, and a bearing life judgment means for determining whether the life of the bearing is good or bad based on the output of the vibration acceleration sensor. A rotating anode X-ray tube device characterized by comprising: 2. The bearing life determination means includes a low-pass filter and a high-pass filter, the filters separate low frequency components and high frequency components from the vibration acceleration signal, determine the degree of bearing damage from the high frequency components, and detect the low frequency components. 2. The rotating anode X-ray tube device according to claim 1, wherein the rotating anode X-ray tube device detects rotational speed and/or unbalance. 3. A claim in which the bearing life determination means includes a double integration circuit, converts a vibration acceleration signal into a vibration displacement signal, and detects the rotation speed and/or unbalance from the vibration displacement signal. Item 1. The rotating anode X-ray tube device according to item 1. 4. The rotating anode X-ray tube device according to claim 1, wherein the vibration acceleration sensor is covered with a thin lead plate.