JPH10233184A - Device for driving x-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the life of a device and detect locking of a motor or situations under which the motor is likely to be locked. SOLUTION: A motor 4 driven by an inverter 3 has an X-ray tube anode directly coupled to its rotor, and a fluid bearing is used as its bearing. Open phase detection means 5a-5c are provided on the output side of the inverter 3, their detection signals being imparted to a control circuit 6. A measurement taken by a power converter 7 for measuring the power consumed by the motor 4 is converted into a voltage, which is given to the control circuit 6. The control circuit 6 compares the measurement of the consumed power by the power converter 7 with a preset reference range to determine whether it is normal or abnormal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray tube driving device for rotating an X-ray tube anode by a motor.

[0002]

Conventionally, an X-ray tube driving device performs X-ray bombardment while rotating an X-ray tube anode by a direct drive type motor. A ball bearing is used as a means.
However, this conventional one has a problem that the life of the bearing is short. As an alternative to this, it has been considered to use a fluid bearing to extend the life of the bearing and, consequently, to extend the service life of the drive unit.

[0003] However, in this case, when the fluid in the hydrodynamic bearing is cooled to a room temperature or lower, there is a possibility that the rotation of the X-ray tube, that is, the motor is locked. If this lock is not detected, the locked state may be left unattended, causing burnout of the motor or damage of other related parts.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to extend the service life of an apparatus, and to detect a motor lock or a situation in which a motor lock is likely to occur, and An object of the present invention is to provide an X-ray tube driving device capable of preventing burnout and damage of other related parts.

[0005]

According to a first aspect of the present invention, an X-ray tube anode is rotationally driven by a motor, wherein a fluid bearing is used as a bearing means for the X-ray tube anode, and the power consumption of the motor is reduced. Is characterized in that a power converter for measuring the value of the power converter is provided, and a right / wrong determining means for determining whether the power converter is normal or abnormal based on the measurement result of the power converter.

In this configuration, since a fluid bearing is used as the bearing means of the anode of the X-ray tube, the life of the bearing is extended. In this case, when the fluid of the fluid bearing becomes lower than normal temperature, there is a possibility that the rotation of the motor is locked due to solidification, but the locking can be prevented beforehand. That is, when the solidification of the fluid starts, the rotation speed of the motor decreases. At this time, the power consumption of the motor becomes larger than usual. Therefore, in the above configuration, the power converter for measuring the power consumption of the motor is provided, and the correctness determination means for determining whether the power consumption is normal or abnormal based on the measurement result by the power converter is provided. Based on the measurement result, it is possible to detect whether or not the motor lock or the rotational speed condition at which the motor lock is likely to occur.
Therefore, it is possible to prevent the motor lock from being left unattended, and it is possible to prevent burnout of the motor and damage of other related members. Moreover, in this configuration,
The power converter is a device that reads current and voltage, so that the cost is low. For example, unlike the case where a rotation detection unit of a rotary encoder is used, the cost can be reduced.

According to a second aspect of the present invention, when the X-ray tube anode is started, a voltage higher than the normal drive voltage is applied to the motor for a certain period of time,
Thereafter, a normal drive voltage is applied, and when the normal drive voltage is applied, the correctness judgment unit judges whether the operation is normal or abnormal. If the judgment result is abnormal, control is performed such that the voltage application pattern and the judgment operation are repeated a certain number of times. The feature is that the drive control means is provided.

When the anode of the X-ray tube is started, the fluid in the fluid bearing may tend to solidify, and the motor may lock if a normal drive voltage is applied to the motor.
However, in the above configuration, when the X-ray tube anode is activated, a voltage higher than the normal drive voltage is applied to the motor for a certain period of time, so that the X-ray tube anode can be activated without locking the motor. Then, a normal drive voltage is applied thereafter, and when the steady drive voltage is applied, whether or not the X-ray tube anode has been successfully started can be determined because the correctness / absence determination means determines whether it is normal or abnormal. When this determination is abnormal, the voltage application pattern and the determination operation are repeated a certain number of times again. Therefore, even if the startup of the X-ray tube anode fails first, it becomes possible to succeed thereafter.

A third aspect of the present invention is characterized in that drive control means for continuously driving the motor at a voltage lower than the normal drive voltage is provided at times other than during X-ray bombardment and during standby for X-bombardment. . When starting the X-ray tube anode for X-ray bombardment, if the temperature of the fluid bearing portion is low, the fluid tends to solidify and the motor may lock. However,
In this configuration, since the motor is continuously driven at times other than during X-ray bombardment and during standby for X-ray bombardment, the fluid bearing portion can be preheated, and motor lock is prevented,
The X-ray tube anode starts well. In this case, since the motor is driven at a voltage lower than the normal drive voltage, power consumption can be reduced.

According to a fourth aspect of the present invention, an X-ray tube anode is rotationally driven by a motor, wherein a fluid bearing is used as bearing means for the X-ray tube anode, and an inverter is used as driving means for driving the motor. An open phase detecting means for detecting an open phase on the output side of the inverter, a power converter for measuring the power consumption of the motor, and a right / wrong determining means for determining whether the power converter is normal or abnormal based on the measurement result by the power converter. A high voltage is applied to the motor for a certain period of time when the X-ray tube anode is started to rotate, and then a normal drive voltage is applied. Is abnormal, the voltage application pattern and the determination operation are controlled so as to be repeated for a certain period of time. Continuously driving the motor in the stomach voltage has a feature where the open phase by the open phase detecting means is provided with a drive control means for stopping the driving of the inverter when it is detected.

In this configuration, the life of the bearing is prolonged, so that burnout of the motor and damage of other related parts can be prevented beforehand, and the cost can be reduced. Further, when the motor is driven by the inverter, the phase loss can be detected by the phase loss detecting means, and damage to the power switching element and the like of the inverter can be prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a CT scanner will be described below with reference to the drawings. FIG. 1 shows an electrical configuration. An inverter 3 is connected to a three-phase 200 V power supply 1 via a noise filter 2. The inverter 3 drives the motor 4 for driving the anode of the X-ray tube, and includes an AC / DC conversion circuit capable of varying a DC output voltage, an inverter main circuit having a power switching element, and the like. ing.
Although not shown, the motor 4 has an X-ray tube anode directly connected to its rotor, and a fluid bearing is used as its bearing. Further, on the output side of the inverter 3, open-phase detecting means 5 a, 5 b, 5 c composed of, for example, a current converter are provided, and the detection signal is supplied to the control circuit 6. Further, a power converter 7 for measuring the power consumption of the motor 4 is provided.
Is to measure the power consumption of the motor 4 by reading the current and the voltage. The measurement result is converted into a voltage and given to the control circuit 6.

The control circuit 6 includes a microcomputer, which has a function as right / wrong judgment means, and converts the power consumption measurement result (voltage level) of the power converter 7 into a digital signal. , A normal range or a normal range is determined by comparing with a preset reference range. This reference range is set to a voltage level (in this case, a voltage range of 1 to 4 V) corresponding to the electric power when the motor 4 is rotating normally. In a situation where the motor 4 is not locked or the rotation does not start up significantly, the power consumption is high. In this case, the measurement result exceeds the upper limit 4 V of the reference range, and it is determined that the motor 4 is abnormal (abnormal due to motor lock). In addition, the measurement result indicates that the lower limit of the reference range is 1V.
If the value is lower than, it is determined as some kind of abnormality. The control circuit 6 receives the above determination result and the detection results of the phase loss detecting means 5a to 5c, and transmits them to the system side of the CT scanner.

Further, the control circuit 6 also has a function as drive control means, and these means will be described below together with the operation description. FIG. 2 shows a change in the voltage applied to the motor 4 when the power is turned on. When the power is turned on, the control circuit 6 first applies 200 V for 6 seconds, and then switches to 120 V, which is a normal drive voltage (drive voltage at which X-ray irradiation is performed). When five seconds have elapsed (time t1), the rotation state of the motor 4 is determined based on the measurement result by the power converter 7.

That is, the voltage of the measurement result is in the reference range 1 to
If it is within the range of 4 V, it is determined that the motor is normal (good startup, that is, the rotation of the motor is satisfactorily started), and if it is out of the range, it is determined that the motor is abnormal (start failure). At the time of this abnormality determination, the voltage is raised again to 200 V and held there for 6 seconds, then switched to 120 V and the above determination operation is performed again. If it is determined that the abnormality continues to be determined,
This voltage application pattern and the determination operation are repeated for 40 minutes. When the normal state is determined (time point t2), the voltage is set to 100 V
Drop.

In this state, as shown in FIG. 3, the rotation status of the motor 4 is determined based on the measurement result of the power converter 7 at intervals of 5 seconds. Leave it alone. When an abnormality is determined, the applied voltage is raised to 200 V and held for 6 seconds, and then switched to 120 V, and after 0.5, it is determined whether the abnormality is normal or abnormal. And if it is abnormal, the motor 4 is stopped.

When an X-ray bombardment standby command is given from the system to the control circuit 6 during the above-described steady rotation, the voltage is increased to 120 V, and the motor 6 is driven by this voltage.
Thereafter, X-ray bombardment is performed on the system side. During this X-ray bombardment standby, normal / abnormal judgment is made by comparing the measurement result of the power converter 7 with another reference range, for example, at intervals of one second. On the other hand, when any of the phase loss detecting means 5a to 5c detects a phase loss, the control circuit 6 turns off the power switching element of the inverter 3.

In such an embodiment, since the fluid bearing is used as the bearing means of the anode of the X-ray tube, the life of the bearing can be extended. In this case, when the fluid of the fluid bearing becomes lower than normal temperature, the rotation of the motor may be locked due to solidification, or there is a possibility that the rotation state is likely to be locked, but according to the present embodiment, the motor lock or the motor lock is likely to occur. Such a situation can be detected, and burnout of the motor 4 and damage of other related parts can be prevented. That is, when the solidification of the fluid in the fluid bearing starts, the rotation speed of the motor 4 decreases. At this time, the power consumption of the motor 4 becomes larger than usual. Therefore, in this embodiment, the motor 4
The power converter 7 for measuring the power consumption of the motor 4 is provided, and the control circuit 6 is provided as a right / wrong determining means for determining whether the motor 4 is normal or abnormal based on the measurement result of the power converter 7. Based on the measurement result, it is possible to detect whether or not the motor 4 is locked or at a rotational speed that is likely to be locked. Therefore, burning of the motor 4 and damage of other related parts can be prevented beforehand. Moreover, according to the present embodiment, the power converter 7 is a device that reads current and voltage, so that the cost is low. For example, unlike the case where the rotation detecting means of the rotary encoder is used, the cost can be reduced.

When the X-ray tube anode (motor 4) is started, the fluid in the hydrodynamic bearing tends to solidify, and the motor 4
If the normal drive voltage is applied at the time of starting, the motor 4 may be locked. However, according to the present embodiment, the motor 4 can be started without being locked by applying a voltage higher than the normal drive voltage to the motor 4 for a fixed time (6 seconds) when the motor 4 is started. Then, a normal drive voltage is applied, and when the normal drive voltage is applied, whether the X-ray tube anode has been properly started can be determined because the control circuit 6 as the right / wrong determination means determines whether the X-ray tube anode is activated properly. When this determination is abnormal, the voltage application pattern and the determination operation are repeated a certain number of times again. Therefore, even if the startup of the X-ray tube anode fails first, it becomes possible to succeed thereafter.

Furthermore, according to the present embodiment, the motor 4 is continuously driven at times other than during X-ray bombardment and during standby for X-ray bombardment, so that the fluid bearing portion can be preheated. Is prevented, and the X-ray tube anode can be started well. In this case, since the motor is driven at a voltage lower than the normal drive voltage, power consumption can be reduced.

Further, according to the present embodiment, the open phase detecting means 5
When the phase loss is detected by any one of a to 5c, the control circuit 6 turns off the power switching element of the inverter 3, so that damage to the power switching element and the like of the inverter 3 can be prevented.

[0022]

As apparent from the above description, the present invention has the following effects. According to the first aspect of the present invention, it is possible to extend the life of the bearing and thus the entire device, and it is possible to detect whether or not the motor lock or the situation in which the motor lock is likely to occur. It is possible to prevent damage to other related parts. In addition, the cost can be reduced.

According to the second aspect of the present invention, even if the activation of the X-ray tube anode fails first, the activation can be succeeded thereafter. According to the third aspect of the invention, the motor is continuously driven at times other than during X-ray bombardment and during standby for X-ray bombardment, so that the fluid bearing portion can be preheated, motor lock is prevented, and The tube tube anode can be started well, and in this case, the motor is driven at a voltage lower than the normal drive voltage, so that power consumption can be reduced.

According to the fourth aspect of the present invention, it is possible to prolong the service life of the bearing and hence the entire device, and to detect whether or not the motor lock or the situation in which the motor lock is likely to occur. It is possible to prevent burnout and damage of other related parts. In addition, the cost can be reduced. Further, when the motor is driven by the inverter, the phase loss can be detected by the phase loss detecting means, and damage to the power switching element and the like of the inverter can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electrical configuration showing an embodiment of the present invention.

FIG. 2 is a time chart showing the relationship between voltage control and normal / abnormal judgment results at startup.

FIG. 3 is a time chart showing a relationship between voltage control and a result of normal / abnormal determination after startup.

[Explanation of symbols]

Reference numeral 3 denotes an inverter, 4 denotes a motor, 5a to 5c denote missing phase detecting means, 6 denotes a control circuit (correctness determining means, drive control means), 7
Indicates a power converter.

Claims (4)

[Claims] 1. An X-ray tube anode being rotationally driven by a motor, wherein a fluid bearing is used as bearing means for the X-ray tube anode, and a power converter for measuring power consumption of the motor is provided. A driving apparatus for an X-ray tube, comprising a right / wrong determining means for determining whether the converter is normal or abnormal based on a measurement result of the converter. 2. When the X-ray tube anode is started, a voltage higher than the normal drive voltage is applied to the motor for a certain period of time, and then the normal drive voltage is applied. 2. The X-ray tube driving device according to claim 1, further comprising a drive control unit that controls the voltage application pattern and the determination operation to be repeated a predetermined number of times when the determination result is abnormal. 3. The X control system according to claim 1, further comprising a drive control unit for continuously driving the motor at a voltage lower than the normal drive voltage during the time other than during X-ray bombardment and during X-ray bombardment standby. Drive device for wire tube. 4. An X-ray tube anode rotatingly driven by a motor, wherein a fluid bearing is used as a bearing means of the X-ray tube anode, and an inverter is used as a driving means for driving the motor. An open-phase detecting means for detecting an open phase on the side of the motor; a power converter for measuring the power consumption of the motor; When the tube anode is activated, a high voltage is applied to the motor for a certain period of time, then a normal drive voltage is applied, and whether the normal drive voltage is applied is determined by the correctness / impropriety determination means to determine whether the motor is normal or abnormal. The voltage application pattern and the determination operation are controlled so as to be repeated for a certain period of time. A drive control means for continuously driving the inverter and stopping the drive of the inverter when the phase loss is detected by the phase loss detection means.